Your video has really helped me to understand why I am getting so much moisture in my loft. I didnt realise I had such a problem until I went to get my christmas decs down yesterday. I was absolutely horrified and panicked, all I could see was loads of money and the big problem of trying to search for a proper decent builder to resolve the issue, with Christmas on the horizon, difficult. But after watching your video I calmed down and began to think how I coould tackle the problem sensibly. Been up there today and have a plan!! Thank you so much for your help Roger.
Get rid of moisture sinks like cardboard, use plastic boxes, lay everything flat so air can move around your loft. Make sure loft hatch is sealed up good. Vent bathroom after a shower, get a dehumidifier on the landing, get a hygrometer to keep track of humidity levels upstairs. close the kitchen door when cooking, use the fan hood to vent cooking humidity.
I use a low energy dehumidifier to keep relative humidity at around 55%.I am amazed at the amount of water it pulls out of the atmosphere.Stops condensation on windows and eliminates potential mould and other nasties for wellbeing.I am very satisfied with the results.
Yeah, we’ve got a dehumidifier which can pull 20L of water a day from the air but it costs (in Aug 2022) about £600 a year to run which is not great. What we’re doing now is only using it when drying clothes indoors where it becomes effectively a heat pump tumble drier without the “tumble”. We’ve actually got a heat pump tumble drier as well and I need to do an exercise to see which is actually more efficient! What worries me more is that, in our loft, the slate nails penetrate the sarking boards and droplets of water condense on the nail points in winter and drip onto the loft floor. I don’t see any signs of an effective vapour barrier between the heated part of the house and the loft so I think we need to improve that as best we can but also improve the ventilation of the loft which seems minimal at best. Why don’t surveyors find basic stuff like this when surveying houses for potential buyers? 🤷♂ Going back to the dehumidifier, if you are going to use one then don’t use it while simultaneously ventilating the house with open windows. If you do this then all you’re doing is dehumidifying the planet! which is an expensive exercise in futility. My suggestion is to dehumidify overnight when electricity is potentially cheaper and the windows are closed. And do it in areas of the house which can benefit most. But as Roger said, try to ventilate cooking steam or shower steam at source via ducted ventilation. We’ve been guilty of turning those off because the humming noise is annoying but I can see now that they are important. Thanks again Roger. 👍
@@craigchamberlain Heat pump should be more efficient. Is there no option to dry outside or semi-outside or in a room with windows open and doors closed so the vapor goes outside vs around your home?
Bought a house built in the 1950s a few years ago. Huge unaddressed mold problems and very steamed up windows in the evenings. I installed some soffit vents (there were none) and a PIV unit in loft. No more problems, cheap and easy to install as well.
The ‘he means fewer problems’ caption absolutely made my day. My wife and I always argue about this. I say it should be fewer, and she’s wrong. I’d never criticise a word a legend like Roger says obviously, but still...
Dylan and I have a running joke about this and I can't believe I got it wrong. Dylan put in the correction and he is right. The rule is very simple. If you can quantify it with a number it is 'fewer' if you can't then it is less. So "fewer people came to the concert this year which made it less crowded." My five says we have less money because fewer customers are willing to pay my extortinate rates.
Spoken like a true journalist Roger. I did 13 years on a local paper and went from being told off to doing the telling off on that one over that time. I have a damp porch built less than two years ago. The builder has been back a few times already and hoping he’ll have it sorted soon but wondering if some of your wisdom in this video is relevant. Will take those down lighters out and have a nosy inside the flat roof...
Roger you're brilliant i hope the all mighty gives you very long life and you can go on teaching us,you are one in million i love yours and Robins veidos great job well done.
Just bought a 50s bungalow and putting in an ensuite bedroom upstairs under PD.. Most of the airbricks have been covered up at the ground floor which has meant the floorboards and joists were soaking wet when we pulled the carpets up 🙄. New airbricks going in all around the perimeter of the suspended floor, membranes and in line extractor fans all round too. Thanks for the advice and explanation on the channel. Very helpful!
Lets say a builder plants a lump of 5x2 along the width of the properties behind the facia board which blocks off the air vents and air flow then that has created a problem. This is the case on new builds in entire rows and these properties suffer badly from moisture in the loft spaces causing moldy ceilings
@@kevinrobertfrasier1309 - not sure what you mean, Kevin, I've never seen anything behind the fascia, they're usually fixed to the rafter ends, and the vents are underneath on the soffits. Builders also use plastic under-felt vents between the joists allowing air to pass by keeping the insulation from blocking the ventilation path. At least in the UK, though you may be referring to builders in other countries?
@@thetessellater9163 this is what my loft is like. (5 year old redrow house) but the insulation had been shoved right down into the eves squashing the plastic vents closed. We had bad condensation when we moved in 8 weeks ago but I unblocked these added felt lap vent, re secured the fan hose vent. And so far so good no more condensation
Absolutely Roger, another great video. I've had plenty of time now to observe how Stormdry is working effectively on my weather facing exposed brickwork on our 13 year old Redrow house. Last year at this time we were facing a complete mess with water penetrating the cavity. No such problem now and water literally bounces of the outside walls. No issues with condensation either, plenty of vents and air flow and as you rightly say Stormdry allows moisture to exit the bricklayer without allowing larger rain and water in. Simple physics really. Keep the videos coming :)
So glad I followed your recommendation and applied Storm Dry to the outside walls of our 1960's bungalow last summer, what a difference it has made and the house feels warmer.
Thanks Roger, very informative. The only thing missed is the Blue Peter solution for bitumen felt by using polystyrene wedges between the sheets to enhance the airflow.
You can seal areas of your house to prevent water vapour inside travelling to other areas such as the roof or walls. But you do not stop condensation problems, only move the problem to another part of the house.. Seal one area, water vapour with find the next coldest area and condense, seal that area, the vapour will the next coldest part of the house and so on. My house house is well sealed, but I have am am the extremes of the problem, where the coldest part of my house is now the hinges on the external doors and windows, and I have pools of water here. There is only one way to stop condensation, seal the house, but add a heat recovery system, it will remove the worst of the vapour with the benefit of heating cost savings and filtered air.
That was really interesting, been thinking about what to do in our 1890 cottage, decided to leave it as it was built, only lambs wool in the loft, its draughty and sometimes cold but bang the woodburner on and its toastie, cool in the summer too. Old tech is sometimes the best tech.
Originally, Bathroom and extractor fans relied on manual on/off switching, and then were improved with a timer device that kept the fan running for an extra 20 minutes or so after switching off. Nowadays there are humidity controlled extract fans that switch on/off automatically whenever the humidity levels rise. Surely this should be a requirement written into the building regulations?
I added a flow switch to a hot water feed to a bath and shower that triggers the bathroom fan. This means it comes on when it is most needed and does not require anyone to remember to switch it on or off.
To Nick, I was into industrial ventilation from day 1 at work in a tannery, smells, steam, and the more the merrier. That was 1963 and industrial buildings leaked but if the fans ran no mould. 1968 Powrmatic manufactured a comprehensive range of industrial fans. As an R&D engineer I had to address the more scientific approach. Large buildings weren't so well sealed and large large volumes of air extracted and more attention to replacement air was for 340 days in the UK at a lower RH, relative humidity, each year. 19 years and more attention involved with gas and oil combustion for heating and process, tiles,ovens, gas registration with CORGI was a minor nuisance in my life (Roger), Involvement with Modecon Boilers in Poole, the first commercial industrial GAS condensing Boiler in the world as I believe the history as I was Dr Harry Cheetham's boiler to be. I was Harry's service engineer and each module was 50kw and multiple modules were the new science commencing with one, two three and on. Harry did build 23 module unit back to back with another 23 module it was that flexible. (A FOOTNOTE - Harry sold of Stelrad who produced the same modular unit as the Concord Super to this day. Hamworthy were miffed with Harry's development of the boiler during the time of his employment so an intellectual rights began and Hamworthy produced with the Wessex modular for the next 26 years, 2021.) Air conditioning was a serious involvement for me, industrial to the tune of computer halls for the MOD and pharmaceuticals and Roger was correct about the temperature differentials and crossing the vapour barriers of air con with any size of all buildings. I moved to Vent Axia with a progressive MD Peter Norris and he saw where leisure and ventilation was heading. The Solo 100mm diameter fan range with modular controllers including variable speed fan control. Brilliant for many public sector houses, expensive electric heating, double glazing added,the result, black mould. Cured with variable speed humidity control improving living conditions for 10,000s problem properties including my own property. That was 1987 and so much of the intervening years not enough attention to ventilating all properties and industrial buildings. Kids with asthma, allergies and other illnesses nor that I've medical knowledge other than acquired knowledge building the environmental control systems a and building the air con systems for isolation rooms for identifying allergies. To that end and for your own homes, VA had one control option and it may still be an option, a two speed toilet fan either with a pull cord for high speed during use the bathroom/toilet. When the light is off the slow speed runs 24 hrs very low energy but not ,zero. The RIBA, the architects body was all home's required on air change per hour, every hour. Before double glazing, plastic doors, air bricks with Hit & Miss ventilation control to slide in the coldest weather. Sweden, a colder country had better insulation in 1936 which we matched around 1980. They knew an RH above 75℅ was the top limit. Google how much water people exhale every hour plus pet, sweating, cooking, hot drinks, airing clothes. A long list, washing, bathing ,showering and on. Covid 19 - I've printed q Permanent negative ventilation, extract, for homes and every building Taking your option Martin with a flow switch for fan control is a useful control without wishing to sound patronising. Humidity does maintain after a shower if the RH is measured knowing steam does hold a great deal of moisture if it's weighed and will attach to all cold surfaces and mirrors are the prime demonstrator. This is a waste product in my list of definitions of products that aren't good for our well being, all included by the Swedes but sometime they recovered 70℅ of the heat with an air to air heat exchanger. VA did get in energy saving for public housing with Southampton City Council with their Hot Rocks project to produce heating and hot water from a bore hole, my involvement was the ventilation and reclamation o heat back into warm the fresh make-up air to save tenants outlay. All Swedish thinking from years back. My last thoughts about the containments we live with and its the produced ts or by products of our homes. I've had air tests done for something like 80? gases, new car
This is exactly my situation. I’m in the top floor of a housing association flat. They own the roofing space and put down plastic sheeting. But moisture forms at the edges on the inside of the bedrooms and runs down the light fixtures. They’ve stopped doing repairs for leaseholders. They’re knocking all the flats down and putting us all back in new ones. I feel like the best solution is to avoid living below a roofing space forever 😔
It gets to a point where the damage from condensation, outweighs the cost of the energy you save from using too much insulation and causing the problems in the first place.
What a video of information. Question : I live in an old house, no roof vents and the style of roof prevents facia vents, I noticed recently moisture on insulation i installed 3 years ago. Would It help by installing gable vents or vented extraction fans and if so would they both need to be extraction or would one have to be just vented for circulation? Would appreciate any advice, many thanks from Ireland
For anyone with PIR immediately below the tiles in their loft (as opposed to being on the floor of the loft) remember the importance of NOT pushing the PIR flush against the underside of the tiles/membrane. You need to leave a 50mm gap for ventilation to flow (this ventilation will come from the soffit vents). If you push the PIR hard against the tiles, the warm air in the loft will travel through the PIR and will condense upon hitting the cold underside of the tile and drip back through the edges of the PIR board back into your loft space. I’ve learned this the hard way! Pulling the PIR away from the tiles a couple of inches has completely solved my issue.
The best way to achieve this is with counterbattens and even 25mm is enough. The water that condenses on the underside of the tiles drips onto the breather membrane but the gap between the tile battens (laths) and the membrane allows the water to run down the membrane to the gutter rather than collecting behind the battens. It is a strange anomaly that our often stringent Building Regs overlook this requirement. In Continental Europe it is almost unheard of not to use counterbattens. If you use counterbattens you can push the insulation board against the felt.
@@SkillBuilder thanks for replying Roger. I didn’t think of counterbattens, wish I had. But I think what I’ve done must be working anyway as haven’t had any repeat of the puddling issues inside the loft that I was having before in particularly cold and still outside weather.
I have a warm flat roof in my kitchen/living room. However, the room is freezing cold in winter and boiling hot in summer. I'm now adding an inverted roof above the EPDM with a living roof above that. I'm hoping the living roof will cool things down in the summer and the inverted roof (Kingspan, Greenshield, Kinspan AquaZone) will keep it all nice and toastie in the winter.
Really good video and explanation of vapour barriers and breathable barriers,it's still complicated to me ,I was in propery maintenance and refurbishment for over 40 years and still find it hard to get my head around, as vapour goes where it wants and stopping it or redirecting it in older properties to cause the least amount of condensation is difficult.thanks
Old working chimneys are an excellent way of getting fresh air into a building and moisture out. Thats some of the problem nowadays as there little to no ventilation in some houses 👍
How about being old school and just leaving the loft floor vapour barrier out all together, because that way you are allowing the moisture concentration in the main living space to dissipate. That is a good thing. Then you can just permit more cross ventilation to your loft space to allow it to vent to atmosphere from up there. Not enough ventilation in modern houses with double glazing etc. Ventilation is important for living in and for structures.
what advise would you give: i have had new roof membrane on a three bed detached house. Installed 4 roof vent tiles, 2 on each side. Plus about 6 or 7 LAP vents each side of the house, im running a 20l dehumidifier upstairs too. However the north side of the house membrane still is covered in condensation? Should i be thinking of upgrading / renewing my insulation? or does this sound like a membrane issue?
I recently had upvc cladding done on the soffits fascias and barge board, cracking job until I went in the loft and found it literally dripping with condensation. Bit of research and found out the continuous air gap under the soffits had been completely compramised by cladding over and replacing with 8 circle vents. Got in touch with company to rectify problem and they didn't have clue about the mm2 formula for ventilation. They eventually turned up and at my request added 32 vents in total, Problem fixed. Basically don't ever cover the soffit vents !
I use a dehumidifier all through the winter in the house. It runs every other day for 8 hrs. I am putting one in the loft too. This is great advice however identifying to origins of water vapour.
my new build's bathroom extractor goes through the loft, but wasnt even connected to the pipe work! so for one whole year we piped hot wet air straight in to the loft space!
Vapour migrating through the building fabric is also responsible for heat loss though it’s not a huge factor it all adds up. Great vid. So many builders get confused when it comes to vapour barriers and condensation. I’m a chippy and I’ve lost count of the times I’ve had to explain all of this to a contractor. Only thing I’m not convinced of is how often is it warmer outside the dwelling than inside. Without a/c where I live on the south coast uk I suggest it’s very rare indeed.
What about a pitched cold roof in a loft conversion? Using solid PIR between Rafters and other layer of PIR below rafters, why would you want to trap the vapour in the loft?, would you not want it to travel through the roof and out via ventilation gap in the pitched roof. I'm looking at diagrams even from Regulations stating a vapor barrier is needed even in this senario but i cant get head around it. All this PIR has foil fronts and is taped by aluminium tape, gaps filled by filler or gafo tape. Why is a vapour barrier needed in this system?
My council came 3 years ago & insulated our loft above the kitchen, signal story building & did not put a vapor barrier in. & they blocked up the soffit air vents too. when they left they told my wife we should check it every year to see if it was getting damp!
Skill builder could you do a video on what type of vapour barrier should and shouldn’t be use on flat roof there’s loads out but I do feel the knowledge on these is very hit and miss even the building inspectors say all different things
Hi Roger, Ive lived in 2 bungalows that both suffered with condensation, I total agree with your information, old 60’s bungalow had cavity wall insulation at some time and loft full of insulation, windows streamed ever day, I solved it by clearing all the insulation jammed in between the roof rafters at plate level added 6 roof tile vents and good bathroom extractors. Job done. Great skill builder videos Thanks Tony
You can combine a vented loft with insulation at the floor level, just air seal the heck out of it first. Air movement is the biggest issue vs diffusion through solids.
I hung a PIV unit in my loft and for the few quid a year to run (£275 to buy) there's no condensation on the black sheeting under the slate tiles. The loft space is about 11.5m x 5m. I guess a normal fan would have similar results. NOTE: the air circulation will stir up the floor insulation so wear a decent mask in the loft.
Just got 1976 old house and has no insulation or soffit vents, would thermawrap have any good impact with the insulation on my loft floor without affecting and increase the risk of damp?
Could you explain why the new build houses with pitched roofs, have vents in the apex please? Are they permitted? Can they covered up? With these its letting alot cold air which like you said hot air will travel to cold, so that air is trying to escape with the ceiling, loft entrance etc
Perfect explanation Roger. We bought 1958 end terrace house with bitumen felt under concrete tiles.Previous owner never had dampness in the attic,that was only storage place thanks to little insulation on joist level....hardly 100mm.I have put another 350mm and loft legs and boarded. This winter there is lots of condensation on rafters and some black mould.. I have to mention roof is unvented. If I replace tiles,put there new breathable membrane like Tyvek and install over the fascia vents and dry vented ridge,will it solve the problem? Can I after that put some kingspan PIR between the rafters,if course keeping 40mm vent gap , to keep loft storage bit warmer?
Another excellent stream. Just one question. Can you use Storm Dry on pebble dash. Or does it have to be on brickwork? And thanks again for an excellent channel.
I just fixed the loft hatch door..it was insulated with rock wool under plastic😮 it was wet and moulding.. now has 5 cm insulation board protected with aluminum waterproof tape. And used draught excluder around the edges.. check soon is it worked.
Hi, I have been living in this small bungalow ( built in the 70s) for 6 years now. I fitted a loft hatch and floored half the attic. My wife complained me going up there as a cold draft was coming down into the house. So I pushed foam ( from old sofa's) into air ducks below the gutters within the loft = 6 years down the road I noticed algae inside the fitted wardrobe which resulted in clothing being thrown out! Watching this blog of your got me to remove all this foam, got myself a humidifier as the sheet of wood on loft roof/ceiling was wet (next to outside wall) The insulation in my loft is the old paper/fibreglass that has seen better days - should I replace the insulation with new insulation? There is two air vents at back of house and two vents at front of the house ( on wood which the outside gutters are attached too) Should I have a vent fitted to roof (outside_ Or should/could I fit two or more air vents under the wood that holds the outside gutters? Cheer Roger - So glad I tune in on your blog!
My house is built in 2001. The attic has bitumen sheet under the tiles. Now in this cold weather it started to sweat. The attic is insulated 300mm earthwool and at some areas PIR with loftboard. I constantly monitor the temp and humidity. Now outside is - 1.4 C 91%humidity. Attic. 4C and 85% humidity. there is ventillation at the eaves and I also installed a fan to suck out the air through the vent at the top of the roof. Felt lap vents also installed 10pc. And there is still water droplets forming on this hopeless bitumen layer. Creating a full vapour barrier is quite a large job. I cant imagine doing that on all the floors. Partially is done on 30% of the area. What I know is that the plasterboard is covered with alu foil on the attic side. So even that must be a good vapour barrier. Still too much moist air escapes and stays in the attic. Is there anything I should, do? thanks
New roof ,loft boarded and raised, problem with condensation, would vents in the roof sort or insulation between the roof rafters?,Got a dehumidifier in what is sorting at least 80%
Hmm? I thought the moisture was coming in with the air circulating through our vented soffits. Do I need to have extra vents installed in the tiled roof... or do I need to install a dehumidifier in the loft space???
Yes good explanations roger ive just done a warm and cold roof at home no vapour barriers although I think p I r insulation has a barrier on it anyway I would say it’s worth mentioning that on a cold roof cross vent with battens is essential and with a warm roof I’ve done exactly as you explained the only problem I get is a bit of friction between the insulation and the ply when the sun gets on it and makes a bang as it warms so may need something between 👍
Thank you. I've just started noticing white spots on my loft interior roof ply. I thought I had a problem with my roof. This totally makes sense as I have downlighters in every room. Also the white dotting/clouding is mostly above shower room
Thank you for the brilliant video/lecture! It answered all questions which have been running through my head for the last few years. I'm interested in the case which there is a solid brick wall with a 100mm external insulation, rendered with ciment+sand+lime? Many thanks!
Before I retired I worked as a building inspector for the NHBC. When I witnessed a vapour check installed at ceiling level below a roof space I asked the builder to remove it as it causes mould to build up in the ceiling as the moisture struggles to escape.
I currently have the same problem with pitched roof condensation. This has happened since I have much improved my loft insulation gaps around my 22 down lights, upto 300mm in some places. The £320 month energy bill is why I did this.
Thank you. It answered a question i left in the comments on a later video. I dont know why I didnt see this video when it was uploaded. I want to build a cavity wall without plastic but with Rockwool and ventilation. For rainproofing I want to use lime.
Great that you covered this area. My personal experience is that when you are in as much of tiny a doubt then vent… and never put outside wall dressing directly up against the wall, without a airgap, if the inside of the house is dressed with plastic because that wall will require desert climate if to ever dry up.
good video on the technical side of how moisture forms but would like to see what you can do and what products you can use to help reduce moisture to a current property with moisture on the felt inside
20:52. its probably due to sealing the insulation with whatever humidity was in the air when the roof was made. its going to move around the system until it condenses on the wood
Loved this video Roger. I’m a novice DIYer having a crack at building myself a fully insulated garden gym. I’m doing cold roof given the 2.5m max height under PD makes a warm roof difficult. Everything you said reinforced what I’ve learnt from hours of scouring RUclips - great to have it all in a sub30min video together. I’m coincidently fitting the VCL to the ceiling and walls this weekend.
@@SkillBuilder yep. 6b2 rafters with 3inch to 0inch firrings on top. 4b2 noggins. 90mm PIR flush against the bottom of rafters. Min air gap of 2inches. Max air gap at end of firrings 5inches. Circular soffit vents at front and back of each rafter run. Also quite a breezy bit of the garden so reckon I’m all good. I am however guilty of the downlights :-) I’ve cut 100mm square holes in the PIR for them and pushed 40mm of PIR back into the hole to sit behind the light. Will take care to polythene tape the VCL edges around the hole into it as best I can. Suspect there will still be moisture leakage but the ventilation above the PIR should help with that anyway.
Great video and love your no nonsense approach! Putting an extractor in a roof will remove the air and stop moisture building up, but it also defeats the point of the insulation since cold air will constantly be drawn in lower down the building from outside to replace the lost air. I put open cell foam into my roof and vents behind that, which stops the massive airflow of an extractor but still allows the roof to breathe and get rid of the moisture. It also costs nothing to run. For me at least, it solved the problem since it's like goretex but insulated.
The fan in the loft blows air into the house to put it under positive pressure thereby forcing the airborne moisture out through the windows and doors provided they have trickle vents
@@SkillBuilder always a pleasure to watch you informative videos Roger. We have a condensation issue in the winter, would you recommend the PIV extractors in the loft to help with the situation as the bungalow has no membrane in the roof, it has fully boarded feather board which the tiles hang off. No leaks but does smell musty in the loft so presuming the extractor will help keeping a constant airflow around the house? Many thanks
Skill Builder I'm thinking about insulating the inside walls of a double brick house which doesn't have a cavity. Im in a conservation area so can't put anything externally, but worry about causing moisture. I think there are lots of people in a similar situation, where the heat loss means the house is never comfortable - either too hot or cold, or with cold areas when the rest of the house is too hot!
What do you do if its not possible to lay a vapor barrier? Old house, floor laid on a large portion of the attic, would need to be removed in order to add a vapor barrier.
@@gregmunro2121 hello Greg. I have had a long relationship with Nuaire; they pioneered PIV over 40 years ago. The unit I always fit is the Nuaire Drimaster Eco Heat model. Second to none - and I’ve fitted all the rest...
@@MostynWitham thanks, would that cure the slight window vapour in the really cold mornings? Washing does get dried occasionally on radiators, it’s a no no, but .....
@@gregmunro2121 we all live in the real world and I’d be a liar if I said that I never dried the odd garment on a rad. Yes the Drimaster heat will get rid of all the window condensation and all the other that you can’t see!! Take a look at my website dovedaledampcure.co.uk For a great video info graphic.
Another question does it make a difference on the flat roof example if you increased the insulation thickness from 30mm to 100mm which would reduce the temperature difference on the inside if it was very cold outside?
Hi Roger, great vidio & insight.. I have an 18th century house in devon. Which all the outer inside walls have been insulated with 50mm board. I've always had a problem since owning the house. On the front wall where it very wet during the winter the storm proof paint continues to bubble. Could you give me some advice please? Been told many different ways but I trust you.. thank you very much
Really appreciate this video and it’s a big help! I’m not a builder but a sparky and I’m trying to gain as much knowledge on this subject as I can for my own house. How would you arrange a vapour barrier if the internal walls are solid brick? In one room (bedroom for example) there is one stud wall & three solid walls. I wasn’t too sure if a vapour barrier should be taped continuously around the ceiling and all walls but then how would plasterboard be fixed to solid walls with a vapour barrier behind? Its very much out of my comfort zone so any help is more than appreciated 😬 It fry’s my brain! Thank you
Hello I'm in a brick house, the question is what do you have behind the bricks? Is it a ventilated facade, is it siding, is it plastered, etc. In general, you should not worry about vapour escaping through the walls when they are tightly plastered. Steam vapors go up and it is good to have a vapor barrier on the ceiling. The question here is whether your ceiling is a wooden structure or solid. Plastderboard is placed on a structure above this structure is placed a vapor barrier.
Another great video from SB. Did anyone else notice that the little man stood in the house dancing about in the living room is naked! If you know what I mean? Lol
it is not exactly as the membrane works - it is not only breathing from inside to outside but it is breathing two ways it depends on which side there is more dampness - that is why is called vapor-permeable membrane or breathable membrane and it doesnt matter if it is DuPont or any other brand. ANd key thing when you pick the membrame is the SD factor
Roofer fitted 3 vents because in gable end terrace its blowing gale,roofing felt has moisture on it i think these vents don't more harm good i don't know what to do.
Even so , most lofts are dryer than the rooms beneath.. Which is where Positive Input Ventillation helps.. I found that installing a NuAire PIV blower much reduced condensation in the house, by pushing (trickling) dryer loft air in through a vent in the landing ceiling. .cost me about £400 and a couple of hours to fit !
Hi Roder.. im after reroofing a house using tivek membrane its a standard a roof..im now going to slab the ceiling with 38mm insulated slabs ..should i use foil back slabs or not ?
Great insight enjoyed it loads! Casting my mind back you did a video talking about insulating beneath your suspended floor with nets and rockwall which you said had drastically improved the heat loss. I need to do mine but want to use celotex between the joists as easier than crawling around on my back! 😄would you say this would be ok ? Cheers M
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My dad (FSVA RICS) would have agreed with every word. This sounds like one of our childhood mealtime lectures. Spot on.
😂😂 the good old boys love it
Your video has really helped me to understand why I am getting so much moisture in my loft. I didnt realise I had such a problem until I went to get my christmas decs down yesterday. I was absolutely horrified and panicked, all I could see was loads of money and the big problem of trying to search for a proper decent builder to resolve the issue, with Christmas on the horizon, difficult. But after watching your video I calmed down and began to think how I coould tackle the problem sensibly. Been up there today and have a plan!! Thank you so much for your help Roger.
Google lap felt vents. Fixed my problem in a few days.
Get rid of moisture sinks like cardboard, use plastic boxes, lay everything flat so air can move around your loft. Make sure loft hatch is sealed up good. Vent bathroom after a shower, get a dehumidifier on the landing, get a hygrometer to keep track of humidity levels upstairs. close the kitchen door when cooking, use the fan hood to vent cooking humidity.
For the first time this year as I got our Christmas decs down from the loft I noticed a lot of damp on the underside of the roof space.
@@mattmechamThankyou, never heard of of them before.
5 pints love it . Makes me think he knows his way round building and the pub . Being a roofer for 30 years plus he's bang on
I haven't been in a pub for over 6 months. It is not the drink I miss though I do like a nice English ale.
@@SkillBuilder lol only joking mate good stuff
I use a low energy dehumidifier to keep relative humidity at around 55%.I am amazed at the amount of water it pulls out of the atmosphere.Stops condensation on windows and eliminates potential mould and other nasties for wellbeing.I am very satisfied with the results.
Check your electricity bill...
Yeah, we’ve got a dehumidifier which can pull 20L of water a day from the air but it costs (in Aug 2022) about £600 a year to run which is not great. What we’re doing now is only using it when drying clothes indoors where it becomes effectively a heat pump tumble drier without the “tumble”. We’ve actually got a heat pump tumble drier as well and I need to do an exercise to see which is actually more efficient!
What worries me more is that, in our loft, the slate nails penetrate the sarking boards and droplets of water condense on the nail points in winter and drip onto the loft floor. I don’t see any signs of an effective vapour barrier between the heated part of the house and the loft so I think we need to improve that as best we can but also improve the ventilation of the loft which seems minimal at best. Why don’t surveyors find basic stuff like this when surveying houses for potential buyers? 🤷♂
Going back to the dehumidifier, if you are going to use one then don’t use it while simultaneously ventilating the house with open windows. If you do this then all you’re doing is dehumidifying the planet! which is an expensive exercise in futility. My suggestion is to dehumidify overnight when electricity is potentially cheaper and the windows are closed. And do it in areas of the house which can benefit most. But as Roger said, try to ventilate cooking steam or shower steam at source via ducted ventilation. We’ve been guilty of turning those off because the humming noise is annoying but I can see now that they are important.
Thanks again Roger. 👍
@@craigchamberlain Heat pump should be more efficient. Is there no option to dry outside or semi-outside or in a room with windows open and doors closed so the vapor goes outside vs around your home?
4:09 @@rsmith02I'm
Bought a house built in the 1950s a few years ago. Huge unaddressed mold problems and very steamed up windows in the evenings. I installed some soffit vents (there were none) and a PIV unit in loft. No more problems, cheap and easy to install as well.
The ‘he means fewer problems’ caption absolutely made my day. My wife and I always argue about this. I say it should be fewer, and she’s wrong. I’d never criticise a word a legend like Roger says obviously, but still...
Dylan and I have a running joke about this and I can't believe I got it wrong. Dylan put in the correction and he is right.
The rule is very simple. If you can quantify it with a number it is 'fewer' if you can't then it is less.
So "fewer people came to the concert this year which made it less crowded."
My five says we have less money because fewer customers are willing to pay my extortinate rates.
Spoken like a true journalist Roger. I did 13 years on a local paper and went from being told off to doing the telling off on that one over that time.
I have a damp porch built less than two years ago. The builder has been back a few times already and hoping he’ll have it sorted soon but wondering if some of your wisdom in this video is relevant. Will take those down lighters out and have a nosy inside the flat roof...
Waitrose had "five items or fewer" checkouts until recently; proper speak!
Roger you're brilliant i hope the all mighty gives you very long life and you can go on teaching us,you are one in million i love yours and Robins veidos great job well done.
Just bought a 50s bungalow and putting in an ensuite bedroom upstairs under PD.. Most of the airbricks have been covered up at the ground floor which has meant the floorboards and joists were soaking wet when we pulled the carpets up 🙄. New airbricks going in all around the perimeter of the suspended floor, membranes and in line extractor fans all round too. Thanks for the advice and explanation on the channel. Very helpful!
I've never used a vapour barrier to the loft. I simply make sure the loft area is well ventilated with soffit vents etc.
Lets say a builder plants a lump of 5x2 along the width of the properties behind the facia board which blocks off the air vents and air flow then that has created a problem. This is the case on new builds in entire rows and these properties suffer badly from moisture in the loft spaces causing moldy ceilings
@@kevinrobertfrasier1309 - not sure what you mean, Kevin, I've never seen anything behind the fascia, they're usually fixed to the rafter ends, and the vents are underneath on the soffits. Builders also use plastic under-felt vents between the joists allowing air to pass by keeping the insulation from blocking the ventilation path.
At least in the UK, though you may be referring to builders in other countries?
@@thetessellater9163 this is what my loft is like. (5 year old redrow house) but the insulation had been shoved right down into the eves squashing the plastic vents closed.
We had bad condensation when we moved in 8 weeks ago but I unblocked these added felt lap vent, re secured the fan hose vent. And so far so good no more condensation
Absolutely Roger, another great video. I've had plenty of time now to observe how Stormdry is working effectively on my weather facing exposed brickwork on our 13 year old Redrow house. Last year at this time we were facing a complete mess with water penetrating the cavity. No such problem now and water literally bounces of the outside walls. No issues with condensation either, plenty of vents and air flow and as you rightly say Stormdry allows moisture to exit the bricklayer without allowing larger rain and water in. Simple physics really. Keep the videos coming :)
That is great to know thanks for telling us. I am sure it will help others
You bought a new build from red row. Good luck 😂
Thanks
Roger is a legend. Can’t get enough of his videos
So glad I followed your recommendation and applied Storm Dry to the outside walls of our 1960's bungalow last summer, what a difference it has made and the house feels warmer.
Water is a excellent thermal conductor.
And it makes bricks much more thermal conductive when it's wet
What has it done for you?
So the water now runs and beads off the bricks better now does it? Saturated bricks allow the cold from the outside in. Is that what you have found?
2 and a bit hours of RUclips and finally a video that explained this to me. Cheers Roger!!!
I trust Roger more than anyone else, his advice and explanation is spot on.
Thanks John, I try to be honest but personally I am a great believer in getting a few opinions and then working out who is telling the truth.
Thanks Roger for the video. Perfect timing as I’m having exactly this issue at the moment!
That half hour flew by! Genuinely interesting and pretty well explained. Your effort appreciated Roger. Stay safe. Paul, Newmarket, Suffolk.
Thanks, will do!
Roger, the loft comment... Spot on. Your experience has proven time and time again you know what you are taking about. Great thanks!
Thanks Roger, very informative. The only thing missed is the Blue Peter solution for bitumen felt by using polystyrene wedges between the sheets to enhance the airflow.
You can seal areas of your house to prevent water vapour inside travelling to other areas such as the roof or walls. But you do not stop condensation problems, only move the problem to another part of the house.. Seal one area, water vapour with find the next coldest area and condense, seal that area, the vapour will the next coldest part of the house and so on. My house house is well sealed, but I have am am the extremes of the problem, where the coldest part of my house is now the hinges on the external doors and windows, and I have pools of water here. There is only one way to stop condensation, seal the house, but add a heat recovery system, it will remove the worst of the vapour with the benefit of heating cost savings and filtered air.
I've been looking for two months for this EXACT video! Thank you! Thank you! God bless
That was really interesting, been thinking about what to do in our 1890 cottage, decided to leave it as it was built, only lambs wool in the loft, its draughty and sometimes cold but bang the woodburner on and its toastie, cool in the summer too. Old tech is sometimes the best tech.
You can't beat the woodburner
Experience, intelligence and expertise. Thanks for sharing Roger. Cheers.
Originally, Bathroom and extractor fans relied on manual on/off switching, and then were improved with a timer device that kept the fan running for an extra 20 minutes or so after switching off. Nowadays there are humidity controlled extract fans that switch on/off automatically whenever the humidity levels rise. Surely this should be a requirement written into the building regulations?
I added a flow switch to a hot water feed to a bath and shower that triggers the bathroom fan. This means it comes on when it is most needed and does not require anyone to remember to switch it on or off.
To Nick, I was into industrial ventilation from day 1 at work in a tannery, smells, steam, and the more the merrier.
That was 1963 and industrial buildings leaked but if the fans ran no mould.
1968 Powrmatic manufactured a comprehensive range of industrial fans. As an R&D engineer I had to address the more scientific approach. Large buildings weren't so well sealed and large large volumes of air extracted and more attention to replacement air was for 340 days in the UK at a lower RH, relative humidity, each year.
19 years and more attention involved with gas and oil combustion for heating and process, tiles,ovens, gas registration with CORGI was a minor nuisance in my life (Roger),
Involvement with Modecon Boilers in Poole, the first commercial industrial GAS condensing Boiler in the world as I believe the history as I was Dr Harry Cheetham's boiler to be.
I was Harry's service engineer and each module was 50kw and multiple modules were the new science commencing with one, two three and on.
Harry did build 23 module unit back to back with another 23 module it was that flexible.
(A FOOTNOTE - Harry sold of Stelrad who produced the same modular unit as the Concord Super to this day.
Hamworthy were miffed with Harry's development of the boiler during the time of his employment so an intellectual rights began and Hamworthy produced with the Wessex modular for the next 26 years, 2021.)
Air conditioning was a serious involvement for me, industrial to the tune of computer halls for the MOD and pharmaceuticals and Roger was correct about the temperature differentials and crossing the vapour barriers of air con with any size of all buildings.
I moved to Vent Axia with a progressive MD Peter Norris and he saw where leisure and ventilation was heading. The Solo 100mm diameter fan range with modular controllers including variable speed fan control.
Brilliant for many public sector houses, expensive electric heating, double glazing added,the result, black mould. Cured with variable speed humidity control improving living conditions for 10,000s problem properties including my own property.
That was 1987 and so much of the intervening years not enough attention to ventilating all properties and industrial buildings. Kids with asthma, allergies and other illnesses nor that I've medical knowledge other than acquired knowledge building the environmental control systems a and building the air con systems for isolation rooms for identifying allergies.
To that end and for your own homes, VA had one control option and it may still be an option, a two speed toilet fan either with a pull cord for high speed during use the bathroom/toilet. When the light is off the slow speed runs 24 hrs very low energy but not ,zero. The RIBA, the architects body was all home's required on air change per hour, every hour.
Before double glazing, plastic doors, air bricks with Hit & Miss ventilation control to slide in the coldest weather.
Sweden, a colder country had better insulation in 1936 which we matched around 1980. They knew an RH above 75℅ was the top limit.
Google how much water people exhale every hour plus pet, sweating, cooking, hot drinks, airing clothes. A long list, washing, bathing ,showering and on.
Covid 19 - I've printed q Permanent negative ventilation, extract, for homes and every building
Taking your option Martin with a flow switch for fan control is a useful control without wishing to sound patronising. Humidity does maintain after a shower if the RH is measured knowing steam does hold a great deal of moisture if it's weighed and will attach to all cold surfaces and mirrors are the prime demonstrator. This is a waste product in my list of definitions of products that aren't good for our well being, all included by the Swedes but sometime they recovered 70℅ of the heat with an air to air heat exchanger.
VA did get in energy saving for public housing with Southampton City Council with their Hot Rocks project to produce heating and hot water from a bore hole, my involvement was the ventilation and reclamation o heat back into warm the fresh make-up air to save tenants outlay. All Swedish thinking from years back.
My last thoughts about the containments we live with and its the produced ts or by products of our homes. I've had air tests done for something like 80? gases, new car
This is exactly my situation. I’m in the top floor of a housing association flat. They own the roofing space and put down plastic sheeting. But moisture forms at the edges on the inside of the bedrooms and runs down the light fixtures. They’ve stopped doing repairs for leaseholders. They’re knocking all the flats down and putting us all back in new ones. I feel like the best solution is to avoid living below a roofing space forever 😔
It gets to a point where the damage from condensation, outweighs the cost of the energy you save from using too much insulation and causing the problems in the first place.
you just have to do it intelligently. that's very easy with new builds if you know what you're doing. it's tricky/difficult with retrofits.
Ventilation is key but it costs money if you have to keep the heating on. Interesting article, thanks.
Cost less than rebuilding the house from water damadge
What a video of information. Question : I live in an old house, no roof vents and the style of roof prevents facia vents, I noticed recently moisture on insulation i installed 3 years ago. Would It help by installing gable vents or vented extraction fans and if so would they both need to be extraction or would one have to be just vented for circulation?
Would appreciate any advice, many thanks from Ireland
Brilliant explanation Roger, I wish you had of been my school teacher.
sadly I was a very disruptive pupil and gave my teachers a hard time. I would like to go back and apologise but it is too late.
For anyone with PIR immediately below the tiles in their loft (as opposed to being on the floor of the loft) remember the importance of NOT pushing the PIR flush against the underside of the tiles/membrane. You need to leave a 50mm gap for ventilation to flow (this ventilation will come from the soffit vents). If you push the PIR hard against the tiles, the warm air in the loft will travel through the PIR and will condense upon hitting the cold underside of the tile and drip back through the edges of the PIR board back into your loft space. I’ve learned this the hard way! Pulling the PIR away from the tiles a couple of inches has completely solved my issue.
The best way to achieve this is with counterbattens and even 25mm is enough. The water that condenses on the underside of the tiles drips onto the breather membrane but the gap between the tile battens (laths) and the membrane allows the water to run down the membrane to the gutter rather than collecting behind the battens.
It is a strange anomaly that our often stringent Building Regs overlook this requirement. In Continental Europe it is almost unheard of not to use counterbattens.
If you use counterbattens you can push the insulation board against the felt.
@@SkillBuilder thanks for replying Roger. I didn’t think of counterbattens, wish I had. But I think what I’ve done must be working anyway as haven’t had any repeat of the puddling issues inside the loft that I was having before in particularly cold and still outside weather.
I have a warm flat roof in my kitchen/living room. However, the room is freezing cold in winter and boiling hot in summer. I'm now adding an inverted roof above the EPDM with a living roof above that. I'm hoping the living roof will cool things down in the summer and the inverted roof (Kingspan, Greenshield, Kinspan AquaZone) will keep it all nice and toastie in the winter.
Really good video and explanation of vapour barriers and breathable barriers,it's still complicated to me ,I was in propery maintenance and refurbishment for over 40 years and still find it hard to get my head around, as vapour goes where it wants and stopping it or redirecting it in older properties to cause the least amount of condensation is difficult.thanks
I find a nice big open fire is great for driving out the damp. A few purlins get scorched but it gets the job done.
Old working chimneys are an excellent way of getting fresh air into a building and moisture out. Thats some of the problem nowadays as there little to no ventilation in some houses 👍
@@tmgromit4007 they can also et a lot in if it has an open chimney pot have a rain cover
How about being old school and just leaving the loft floor vapour barrier out all together, because that way you are allowing the moisture concentration in the main living space to dissipate. That is a good thing. Then you can just permit more cross ventilation to your loft space to allow it to vent to atmosphere from up there. Not enough ventilation in modern houses with double glazing etc. Ventilation is important for living in and for structures.
fantastic video. perfectly explains the problems. your roof design skills are top notch.
what advise would you give: i have had new roof membrane on a three bed detached house. Installed 4 roof vent tiles, 2 on each side. Plus about 6 or 7 LAP vents each side of the house, im running a 20l dehumidifier upstairs too. However the north side of the house membrane still is covered in condensation? Should i be thinking of upgrading / renewing my insulation? or does this sound like a membrane issue?
Dry ridge system perhaps?
I recently had upvc cladding done on the soffits fascias and barge board, cracking job until I went in the loft and found it literally dripping with condensation. Bit of research and found out the continuous air gap under the soffits had been completely compramised by cladding over and replacing with 8 circle vents. Got in touch with company to rectify problem and they didn't have clue about the mm2 formula for ventilation. They eventually turned up and at my request added 32 vents in total, Problem fixed. Basically don't ever cover the soffit vents !
I use a dehumidifier all through the winter in the house. It runs every other day for 8 hrs. I am putting one in the loft too. This is great advice however identifying to origins of water vapour.
I Always install a HRV (Heat Recovery Ventilator) Excellent video.
Perfect. I understood everything. Great advice.
my new build's bathroom extractor goes through the loft, but wasnt even connected to the pipe work! so for one whole year we piped hot wet air straight in to the loft space!
I’ve seen this bodge so many times 😬😬
Vapour migrating through the building fabric is also responsible for heat loss though it’s not a huge factor it all adds up. Great vid. So many builders get confused when it comes to vapour barriers and condensation. I’m a chippy and I’ve lost count of the times I’ve had to explain all of this to a contractor. Only thing I’m not convinced of is how often is it warmer outside the dwelling than inside. Without a/c where I live on the south coast uk I suggest it’s very rare indeed.
What about a pitched cold roof in a loft conversion? Using solid PIR between Rafters and other layer of PIR below rafters, why would you want to trap the vapour in the loft?, would you not want it to travel through the roof and out via ventilation gap in the pitched roof. I'm looking at diagrams even from Regulations stating a vapor barrier is needed even in this senario but i cant get head around it. All this PIR has foil fronts and is taped by aluminium tape, gaps filled by filler or gafo tape. Why is a vapour barrier needed in this system?
The PIR under the rafters is a vapour barrier when the seems are taped with foil tape.
Thanks Pal another very interesting vid .... keep them coming
Brilliant video buddy, I had this problem and used those vents you slide between the felt laps, problem solved 👍
My council came 3 years ago & insulated our loft above the kitchen, signal story building & did not put a vapor barrier in. & they blocked up the soffit air vents too. when they left they told my wife we should check it every year to see if it was getting damp!
Skill builder could you do a video on what type of vapour barrier should and shouldn’t be use on flat roof there’s loads out but I do feel the knowledge on these is very hit and miss even the building inspectors say all different things
Thanks Roger, how would you manage the light fittings etc without have to cut holes in the membrane?
Hi Roger,
Ive lived in 2 bungalows that both suffered with condensation, I total agree with your information, old 60’s bungalow had cavity wall insulation at some time and loft full of insulation, windows streamed ever day, I solved it by clearing all the insulation jammed in between the roof rafters at plate level added 6 roof tile vents and good bathroom extractors. Job done. Great skill builder videos
Thanks Tony
Good result Tony.
You can combine a vented loft with insulation at the floor level, just air seal the heck out of it first. Air movement is the biggest issue vs diffusion through solids.
I hung a PIV unit in my loft and for the few quid a year to run (£275 to buy) there's no condensation on the black sheeting under the slate tiles. The loft space is about 11.5m x 5m. I guess a normal fan would have similar results. NOTE: the air circulation will stir up the floor insulation so wear a decent mask in the loft.
Just got 1976 old house and has no insulation or soffit vents, would thermawrap have any good impact with the insulation on my loft floor without affecting and increase the risk of damp?
No rant - very calm and useful thanks 👍
Brilliant, thank you 👍
Thank you so much, this was the best video about vapor control by far. Thank you for sharing your knowledge and explaining it so well.
Do you recommend moisture trays ?
Could you put any foil on boards between rock wool. ?
Could you explain why the new build houses with pitched roofs, have vents in the apex please? Are they permitted? Can they covered up? With these its letting alot cold air which like you said hot air will travel to cold, so that air is trying to escape with the ceiling, loft entrance etc
Perfect explanation Roger. We bought 1958 end terrace house with bitumen felt under concrete tiles.Previous owner never had dampness in the attic,that was only storage place thanks to little insulation on joist level....hardly 100mm.I have put another 350mm and loft legs and boarded. This winter there is lots of condensation on rafters and some black mould.. I have to mention roof is unvented. If I replace tiles,put there new breathable membrane like Tyvek and install over the fascia vents and dry vented ridge,will it solve the problem?
Can I after that put some kingspan PIR between the rafters,if course keeping 40mm vent gap , to keep loft storage bit warmer?
Another excellent stream. Just one question. Can you use Storm Dry on pebble dash. Or does it have to be on brickwork? And thanks again for an excellent channel.
I just fixed the loft hatch door..it was insulated with rock wool under plastic😮 it was wet and moulding.. now has 5 cm insulation board protected with aluminum waterproof tape.
And used draught excluder around the edges.. check soon is it worked.
Hi, I have been living in this small bungalow ( built in the 70s) for 6 years now. I fitted a loft hatch and floored half the attic. My wife complained me going up there as a cold draft was coming down into the house. So I pushed foam ( from old sofa's) into air ducks below the gutters within the loft = 6 years down the road I noticed algae inside the fitted wardrobe which resulted in clothing being thrown out! Watching this blog of your got me to remove all this foam, got myself a humidifier as the sheet of wood on loft roof/ceiling was wet (next to outside wall) The insulation in my loft is the old paper/fibreglass that has seen better days - should I replace the insulation with new insulation? There is two air vents at back of house and two vents at front of the house ( on wood which the outside gutters are attached too) Should I have a vent fitted to roof (outside_ Or should/could I fit two or more air vents under the wood that holds the outside gutters? Cheer Roger - So glad I tune in on your blog!
My house is built in 2001. The attic has bitumen sheet under the tiles. Now in this cold weather it started to sweat. The attic is insulated 300mm earthwool and at some areas PIR with loftboard. I constantly monitor the temp and humidity. Now outside is - 1.4 C 91%humidity. Attic. 4C and 85% humidity. there is ventillation at the eaves and I also installed a fan to suck out the air through the vent at the top of the roof. Felt lap vents also installed 10pc. And there is still water droplets forming on this hopeless bitumen layer. Creating a full vapour barrier is quite a large job. I cant imagine doing that on all the floors. Partially is done on 30% of the area. What I know is that the plasterboard is covered with alu foil on the attic side. So even that must be a good vapour barrier. Still too much moist air escapes and stays in the attic. Is there anything I should, do? thanks
New roof ,loft boarded and raised, problem with condensation, would vents in the roof sort or insulation between the roof rafters?,Got a dehumidifier in what is sorting at least 80%
Hmm? I thought the moisture was coming in with the air circulating through our vented soffits. Do I need to have extra vents installed in the tiled roof... or do I need to install a dehumidifier in the loft space???
Yes good explanations roger ive just done a warm and cold roof at home no vapour barriers although I think p I r insulation has a barrier on it anyway I would say it’s worth mentioning that on a cold roof cross vent with battens is essential and with a warm roof I’ve done exactly as you explained the only problem I get is a bit of friction between the insulation and the ply when the sun gets on it and makes a bang as it warms so may need something between 👍
Thank you, brilliant information
Thank you. I've just started noticing white spots on my loft interior roof ply. I thought I had a problem with my roof. This totally makes sense as I have downlighters in every room. Also the white dotting/clouding is mostly above shower room
Thank you for the brilliant video/lecture! It answered all questions which have been running through my head for the last few years.
I'm interested in the case which there is a solid brick wall with a 100mm external insulation, rendered with ciment+sand+lime?
Many thanks!
Thank you for a very informative video. Should help with my flat roof ventilation problems.
Excellent video. Thanks.
have you any advice on how the successfully insulate an existing corrugated iron
barn roof, that we plan to convert to a domestic house
Before I retired I worked as a building inspector for the NHBC. When I witnessed a vapour check installed at ceiling level below a roof space I asked the builder to remove it as it causes mould to build up in the ceiling as the moisture struggles to escape.
I currently have the same problem with pitched roof condensation. This has happened since I have much improved my loft insulation gaps around my 22 down lights, upto 300mm in some places. The £320 month energy bill is why I did this.
The downlighters are allowing a lot of air up there
Your information is in total agreement with what the cold weather research people in Fairbanks, Ak teach. Well done.
Thank you. It answered a question i left in the comments on a later video. I dont know why I didnt see this video when it was uploaded.
I want to build a cavity wall without plastic but with Rockwool and ventilation. For rainproofing I want to use lime.
This guy is incredible.
Great that you covered this area.
My personal experience is that when you are in as much of tiny a doubt then vent… and never put outside wall dressing directly up against the wall, without a airgap, if the inside of the house is dressed with plastic because that wall will require desert climate if to ever dry up.
What about positive air flow fans in loft to stop condensation buildup on timber rafters and bitumen felt?
good video on the technical side of how moisture forms but would like to see what you can do and what products you can use to help reduce moisture to a current property with moisture on the felt inside
Thanks Rogers, really great understandable video👍
Now I have an image of a sweaty Roger in Lycra in my head!
Or Mrs. Bushy giving off moisture 😉
Great explanation. fantastic understanding of the problem. Every things relative.
Excellent information, condensed into 30 minutes. Thank you very much.
20:52. its probably due to sealing the insulation with whatever humidity was in the air when the roof was made. its going to move around the system until it condenses on the wood
Loved this video Roger. I’m a novice DIYer having a crack at building myself a fully insulated garden gym. I’m doing cold roof given the 2.5m max height under PD makes a warm roof difficult. Everything you said reinforced what I’ve learnt from hours of scouring RUclips - great to have it all in a sub30min video together. I’m coincidently fitting the VCL to the ceiling and walls this weekend.
If you ventilate above the insulation you will be fine
@@SkillBuilder yep. 6b2 rafters with 3inch to 0inch firrings on top. 4b2 noggins. 90mm PIR flush against the bottom of rafters. Min air gap of 2inches. Max air gap at end of firrings 5inches. Circular soffit vents at front and back of each rafter run. Also quite a breezy bit of the garden so reckon I’m all good. I am however guilty of the downlights :-) I’ve cut 100mm square holes in the PIR for them and pushed 40mm of PIR back into the hole to sit behind the light. Will take care to polythene tape the VCL edges around the hole into it as best I can. Suspect there will still be moisture leakage but the ventilation above the PIR should help with that anyway.
Great video and love your no nonsense approach!
Putting an extractor in a roof will remove the air and stop moisture building up, but it also defeats the point of the insulation since cold air will constantly be drawn in lower down the building from outside to replace the lost air.
I put open cell foam into my roof and vents behind that, which stops the massive airflow of an extractor but still allows the roof to breathe and get rid of the moisture. It also costs nothing to run.
For me at least, it solved the problem since it's like goretex but insulated.
The fan in the loft blows air into the house to put it under positive pressure thereby forcing the airborne moisture out through the windows and doors provided they have trickle vents
@@SkillBuilder always a pleasure to watch you informative videos Roger. We have a condensation issue in the winter, would you recommend the PIV extractors in the loft to help with the situation as the bungalow has no membrane in the roof, it has fully boarded feather board which the tiles hang off. No leaks but does smell musty in the loft so presuming the extractor will help keeping a constant airflow around the house? Many thanks
Great video....absolute great.Thank you!!!
Thanks for a brlliant video. Have you thought about doing one about insulating brick houses that don't have a cavity?
External wall insulation. That is an interesting one. I did a training course with Weber so it would be a good idea.
Skill Builder I'm thinking about insulating the inside walls of a double brick house which doesn't have a cavity. Im in a conservation area so can't put anything externally, but worry about causing moisture. I think there are lots of people in a similar situation, where the heat loss means the house is never comfortable - either too hot or cold, or with cold areas when the rest of the house is too hot!
very informative- thank you.
Well explained. Thanks Roger
What do you do if its not possible to lay a vapor barrier? Old house, floor laid on a large portion of the attic, would need to be removed in order to add a vapor barrier.
I reckon a decent PIV system will go a long way to getting rid of household moisture. I fit them for a living Roger and get great results.
What kind of piv do you recommend
@@gregmunro2121 hello Greg. I have had a long relationship with Nuaire; they pioneered PIV over 40 years ago. The unit I always fit is the Nuaire Drimaster Eco Heat model. Second to none - and I’ve fitted all the rest...
@@MostynWitham thanks, would that cure the slight window vapour in the really cold mornings? Washing does get dried occasionally on radiators, it’s a no no, but .....
@@gregmunro2121 we all live in the real world and I’d be a liar if I said that I never dried the odd garment on a rad. Yes the Drimaster heat will get rid of all the window condensation and all the other that you can’t see!! Take a look at my website dovedaledampcure.co.uk
For a great video info graphic.
Hi Mostyn, my main condensation problem is in the loft, would one of these PIV systems be suitable for dealing with this type of problem
Another question does it make a difference on the flat roof example if you increased the insulation thickness from 30mm to 100mm which would reduce the temperature difference on the inside if it was very cold outside?
Hi Roger, great vidio & insight.. I have an 18th century house in devon. Which all the outer inside walls have been insulated with 50mm board. I've always had a problem since owning the house. On the front wall where it very wet during the winter the storm proof paint continues to bubble. Could you give me some advice please? Been told many different ways but I trust you.. thank you very much
Can you send me pictures please? www.skill-builder.uk/send
@@SkillBuilder I will do thanks Roger
Really appreciate this video and it’s a big help! I’m not a builder but a sparky and I’m trying to gain as much knowledge on this subject as I can for my own house. How would you arrange a vapour barrier if the internal walls are solid brick? In one room (bedroom for example) there is one stud wall & three solid walls. I wasn’t too sure if a vapour barrier should be taped continuously around the ceiling and all walls but then how would plasterboard be fixed to solid walls with a vapour barrier behind? Its very much out of my comfort zone so any help is more than appreciated 😬 It fry’s my brain!
Thank you
Hello
I'm in a brick house, the question is what do you have behind the bricks? Is it a ventilated facade, is it siding, is it plastered, etc. In general, you should not worry about vapour escaping through the walls when they are tightly plastered. Steam vapors go up and it is good to have a vapor barrier on the ceiling. The question here is whether your ceiling is a wooden structure or solid. Plastderboard is placed on a structure above this structure is placed a vapor barrier.
Another great video from SB. Did anyone else notice that the little man stood in the house dancing about in the living room is naked! If you know what I mean? Lol
Great video Roger. Regards from Ireland
it is not exactly as the membrane works - it is not only breathing from inside to outside but it is breathing two ways it depends on which side there is more dampness - that is why is called vapor-permeable membrane or breathable membrane and it doesnt matter if it is DuPont or any other brand. ANd key thing when you pick the membrame is the SD factor
Roofer fitted 3 vents because in gable end terrace its blowing gale,roofing felt has moisture on it i think these vents don't more harm good i don't know what to do.
Even so , most lofts are dryer than the rooms beneath.. Which is where Positive Input Ventillation helps.. I found that installing a NuAire PIV blower much reduced condensation in the house, by pushing (trickling) dryer loft air in through a vent in the landing ceiling. .cost me about £400 and a couple of hours to fit !
We are doing something on that unit soon
Hi Roder.. im after reroofing a house using tivek membrane its a standard a roof..im now going to slab the ceiling with 38mm insulated slabs ..should i use foil back slabs or not ?
Great insight enjoyed it loads! Casting my mind back you did a video talking about insulating beneath your suspended floor with nets and rockwall which you said had drastically improved the heat loss. I need to do mine but want to use celotex between the joists as easier than crawling around on my back! 😄would you say this would be ok ? Cheers M
Yes it is better to use Celotex. I used Rockwool for convenience but Celotex is warmer.
@@SkillBuilder cheers Rog much appreciated👍 M