Garden room, Office in the garden, Mancave Vapour control in the roof and walls.
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- Опубликовано: 26 июн 2024
- The first thing to take note of is that you can build these garden sheds, garden rooms, home offices, garden workshops without having building control involved. If you haven't got building control involved, you have no obligation to build them to any standard. However, if you don't want to get any sweating between the walls (known as interstitial condensation) or in the roof, then you need to build to standards, known to perform correctly for the environment for which you are going to use the building. We know that walls and roofs, constructed to the correct specification, work. But I'm often asked, will they still work if a particular element of that construction is left out. The answer is that I don't know. Basically, it will be outside the scope of any robust construction method that has actually been tested.
Now it is most probable that it will work, however if we move too far away from the correct design, then there is a much greater chance that it may not work. When It comes to adding an AVCL (Air Vapour Control Layer) to garden sheds, garden rooms, home offices, garden workshops etc., if the internal moisture content is low, the insulation is fitted tightly and the room is relatively air tight, then you can get away with the wrong AVCL (Air Vapour Control Layer), or even get away with no Air Vapour Control Layer. Unfortunately there is no easy answer to this question but to do the work correctly. With garden outbuildings, you normally have a building height restriction of 2.5m; this makes most people go for an insulated cold roof. Unfortunately these have the greatest failure rate when constructed incorrectly. It is much better to form a new warm roof with a little less insulation, than to compromise the entire flat roof with a badly-installed cold roof.
@Steve Roofer you are an absolute bloody legend.
I have had huge issues with my new extension cold deck flat roof and your videos have helped me so much in what I am looking at and what the issues are
Thanks so much Steve! Another brilliant video! Your advice is priceless!
Hi Steve, not long found your channel but your passion for helping people shine through on the first one I watched. I’m building a workshop in my garden over the coming months and wondered if I could pick your brain on the best way forward for my roof and wall system? Keep the great content coming. Rich
Hi Steve, thanks for your videos. I hope you're still planning to keep them coming in the future.
I was trying to see if you've explained about what to do with the lights since you said people shouldn't cut through the the insulation. Is there a video where you explain the correct method? In a video you said that cutting the vapour membrane will allow a lot of moisture to pass through, so now I'm confused on what's the best way to install lights.
Thanks
Great info - really helped me
Very informative as usual with great attention to detail. Thank you.
Recently found ur channel like the content. How would u do a cold roof with down lights in? How would u get over cutting holes in the insulation? Have u any vids on this thanks
As always, excellent info Steve. 'What would Steve do about it?' Everytime I deal with my Chicago 2-flat, low slope roof.
rock-wool. Excellent old product that deserves its new found respect.
Great retrospective video with re-mediations.
I was wondering, with regards to rubber EPDM. What brands or manufacturers would you recommend?
Thanks
Love some internal holes
Can you recommend any literature regarding hot/cold and hybrid roofs in the UK?
Could we simply use the heavy duty black polythene for damp proof layer on the walls. Or is it too thick? I'm talking about the folded sheeting available from toolstation and screwfix. I could just staple it on or is this not correct. I'm due to build a garden room / workshop.
Steve. Screwfix do a vapour barrier by Capital valley plastics. How would you rate this, it seems good value.
Would be interested to know this also
Any chance you could do a video on pitched roof with breather membranes? I got myself in a mini-panic watching your videos, as I have a cold unventilated roof for my extension, but then I realised that a lot of your videos are flat roofs. I have a pitched one with tiles and use a breathable membrane, with vents in the soffit. Apparently the membrane allows vapour to evaporate, this gets through tiles? Great videos otherwise.
Hi Steve, I currently have a dual pitched, bitumen felt over OSB roof deck, and it has soffit vents. If I replace the felt with box profile metal sheets do I still need to keep the soffit vents or can I block them up since the metal sheets themselves are naturally ventilated due to their profile?
Depends if you take the osb off and have just sheeting with open eaves because of profile it'll be ok if you put sheets on top of a osb deck it'll still need venting below roof deck
Hey Steve Roofer. Can I ask you a question here? I've built a summerhouse in the garden and haven't thought about venting anything until I recently saw your videos. It's framed with 100x50mm pressure treated timber. Whilst I could vent the roof without too much hassle venting the wall cavities is going to be a challenge. The outside walls are UPVC cladding over a polythene sheet and the roof is epdm. So there's not much scope for water to move out if it gets trapped in the walls. It's a dilema and i just asked ChatGPT what he thought and he suggested using closed cell spray foam insulation which means i don't need to worry about venting anything as the foam is a vapour barrier and completely impermiable and there will be no gaps for air or moisture to move across. What say you?
Single ply Warm roof all tge way
Quick question, how is the internal plaster boards fitted? Does screwing them into the beans not pierce the vapour barrier? Thanks
Yes that's why you should use a sealing tape
Steve how flat should the roof be? In order to lay the EPDRM is there a tolerance for flatness say 3mm equal offset over a 2m straight edge? In the roof joists? Or does it need to be perfectly flat? Thanks
its all down to you you coud put bags of sand in the middle and drape it over it wont look good but will work
Very informative video.
I have two questions.
1. Where this customer added a stud wall with rock wool inside of the blockwork. Is there an air gap between the stud wall and the inside of the block or another vapour barrier to prevent ingress of moisture through the blocks from outside? I was considering building a garden workshop similar construction.
2. When fitting a vapour barrier to a ceiling of a block built house, how do you seal the barrier to the wall thats going to have dot & dab plaster boards adhered to it where they butter up the perimeter edge and it would meet the vapour barrier lapped down the wall?
Best and easiest way of explaining this the AVCL (air vapour control layer) always gos on the warm side of any insulation so any ware in the construction of a walls or roof close to the insulation. Alway try to keep the construction simple and only one AVCL in the correct places, this is why I disagree with foil faced insulation as its possibly putting another AVCL in the wrong place and confusing the buildup
@@SteveRoofer Hi Steve, i am doing a similar project and Dan's question 1 would be really helpful to understand. Should there be an airgap between the studwall/insulation and brick? Currently my composition would be: Single skin brick -> studwall and insulation -> vapour control layer -> plasterboard. Im hoping i dont need to leave an airgap between the single skin brick -> studwal & insulation? Could do with the space and installing lots of airbricks.
Archetects often spec visqueen with screws through the top dec of boards into timbers below the insulation. How does screws effect the air tightness of the roof? Do you use this method?
No in a warn roof we use a self healing AVCL (air vapour control layer) that get over that problem
@@SteveRoofer on your other videos with a warm roof you are saying BM Trada say do not put any timber on top of the insulation! So you are saying fix glue a rubber roof directly to the insulation....
Small holes in a vcl don't cause major issues especially if there screw sized. Your told if you have a screw that doesn't bite you have to leave the screw loose within the hole it's created to leave as little space for heat to gain access to the cold roof covering best systems tbh are fully adhered vcl ie felt or alutrix with a pu adhered insulation board. It's like a roof under your roof and as the insulation is glued not fixed it doesn't breach ya vcl
I can’t tell but are the studs up against the block, is that ok or do you recommend a dpc between them and the wall?
Always put a dent proof course in when you're up against the wall
@@SteveRoofer also would you recommend putting rigid foam insulation against the wall, or leave a 20mm air gap. Just asking because i am going to build a single skin brick office and using timber inside filled with insulation.
You are joking why all the ventilation, its a little shed one person a few hours a day. There not going to be a humidity in there to condense.
You don't know that there may be more going on in there one day
hi mate, just built a summerhouse but didn't leave any gap between the roof and the pir insulation, the rubber roof seems to be wet every night when its not raining , i can see the patches in squares on the roof. thanks in advance
send over some photos and destils info@londonflatroofing.co.uk
@@SteveRoofer only just seen your reply thanks mate will send them over tomorrow
I’ve watched video after video after video on all this and still don’t fully get it. What about when you cut sockets out or screw the gyproc on. Bang right through the barrier it’s goosed. And when you seen that guys internal framing the insulation looks like it would easily be too big to allow the 50mm gap at the back. Quite frustrating as fancy doing this in the garage but don’t want to do it wrong. I bet half these guys out the Facebook doing garage conversions and charging PLENTY!!!! aren’t doing half of this you are recommending
You have to have a 50 mil gap and if you cut plugs or anything through the vapour barrier you must seal it correctly
@@SteveRoofer is that just a 50mm gap at the back of the insulation the front can be flush with the joist
If I have 100mm insulation in the roof then fit the vapour barrier can I then fit 50mm insulated plaster boards to the underside or does all insulation have to be above the vapour barrier? Thank you
You put the AVCL under the insulating between the joists and above the insulated plasterboard and sanded it all together
How do I contact you?
you call me or email me its on the top of all my video
The garden room could be considered as a habitable space and therefore must comply with the Building Regs. Outbuildings or sheds don't have to comply because there is no occupation other than for a few moments. This garden room would fail on the structural and thermal regs. The wall structure does concern me because although it is vapour permeable I would expect that interstitial condensation would occur on the warm side of the breather paper. The vent holes in the roof joists are absolutely dire being in the top chord i.e. compression section of the beam. Effectively the joists have been reduced in depth by say 40-50mm i.e. down to the bottom of the lowest hole. Any holes should have been drilled through the neutral axis of the joist i.e. in the middle. This garden room was a very good candidate for multifoil insulation to walls and roof, fully taped or at least a warm roof solution and correct insulation to the external wall.
I am a fan of multifoil insulation that can be used in many ways, not least as a combined vapour barrier and insulation and I have spec'd this as a sarking as well as under/between rafter insulation. The method of setting the insulation allows all the services to pass between the insulation and the face of any say plasterboard that means the vapour integrity is not compromised by the services.
Talk about overkill.