Hi great video, although it been some time I have worked in construction management having come from the trades, so its great to watch a video that is well informed. A lot has changed so I am re-educating myself on some new products, and I have seen a few things on other videos that I question and so I like your point the regard to edpm @ 8:51 you talk about interstitial condensation due to EDPM being glued to OSB over PIR foil back. I have often thought about this. So your saying the the EPDM should be glued directly to the PIR. My only concern with that is how fragile PIR is but I get it, with the cold bridging and the foil and no ventilation in that area due to the sandwich of materials and the possibility for moister to build up from water vaper in the air and getting trapped between the osb and the pir layers. I do have a question as I am planning to build a garden room next year, and was wondering how you would go about designing the base, the total area is 30ms, which will combine both a shed and the garden room. I wondered what your preferred method would be. I am considering both timber suspended or solid concrete. With a suspended timber floor giving 150mm for ventilation would you remove the top soil and lay a 150mm bed of hard core then dpm then the 150mm ventilation void. Or 150mm hardcore 50mm sand blinding dpm and 100mm of concrete with 100mm of pir on top for a floating floor? Thanks
Hi. For the insulation, you secure it mechanically to through the deck to the joists. You never use foil backed. Yes I will always go for suspended floor over concrete. Scrape land, no need for hardcore, DPM and then 50mm blinding concrete to protect DPM , and then as you say, your 150mm ventilated void
I think that Jerry meant like this: Regarding EPDM and condensation, yes, directly gluing the EPDM to the PIR insulation can help prevent that moisture build-up between layers since it avoids the issues with foil-backed OSB. PIR can be a bit fragile, as you said, but keeping it straightforward with fewer layers usually works better for insulation and ventilation. About your garden room, I’d go with a suspended timber floor over solid concrete. Here’s my preferred method: scrape the topsoil, no need for hardcore. Then lay a DPM (damp-proof membrane) directly, with a 50mm blinding layer of concrete on top to protect the DPM. After that, add your 150mm ventilation void under the timber floor.
In England it is common practice to build walls off 'Egger Protect' flooring on garden rooms and also large cabins. Egger Protect is an expensive material so maybe is OK??? Just wondered what your opinion is on this, great video, it is a very good point you have raised about building off chipboard.
Hi. Yes, I understand it’s common practice by some. I see it also on a lot of popular RUclips self build and DIY channels. The reason they do it, I guess, is to make it easier to make their walls right angled, rather than using 345. It’s a terrible detail. You’ll hear the standard “I’ve been doing this for years and never had a problem” answer. Phone up a structural engineer, phone up Egger protect manufacturer as well, and ask if it’s suitable for taking roof point loads, and you’ll have your answer. Have you ever had your kitchen worktop swell up and fail when it gets moisture ingrained? What happens if the weight compresses the tiny air gaps in chipboard? Or part of the composite fails? Of course it’s a rare occurrence. If it fails.. will your builder come back to re build your investment at their cost…. Or pay you compensation? And if you’re doing it yourself…how will you feel if all your hard work is ruined? Why not just do it right in the first place?
@@build-better-things Yes I do get what you are saying, it is a brilliant point. I saw one RUclipsr build his own cabin with a glulam beam to create about a 5m open space, he had about 6 vertical timbers supporting it, all on the Egger Protect, he isn't a commercial builder though. It is a cabin on a steel frame with wheels with an apron cladding system. So the edge of this flooring could be a bit of a potential weak spot I guess.
9:07 I'm looking to add insulation to the external 2x4 walls on my first floor in the way shown in this diagram with the additional insulation to prevent cold bridging. Whats the benefit of using the OSB inbetween the insulation layers? Could it go on the inside of the insulation, directly under the plasterboard? Great video!
The issue would be services and pop throughs. The beauty of frame construction is the integrated service void. Air tightness also might be harder. If you can live with that, I think it’s probably ok, but I might consider omitting it and using bracing instead to deal with the racking, after speaking to an engineer. You would need a reinforced breather membrane but I’ve done it before.
Excellent video, very clearly explained..! Hv u made a video for timber frame, if so pls confirm. I have timber frame on the 1st floor 5” thick studs. Will they be enough to hold a dormer loft conversion. Wht size should the studs be..?
Hi. I’ve made videos about attic conversion, dormer windows, and a load on timber frame. Just have a look at the play lists. I’m reluctant to give advice on timber sizing as it’s always project specific. Thanks a lot for your comment.
I take your point about not adding another OSB on top of a warm roof insulation. My question is, can rubber roofs be safely bonded to foiled backed PIR insulation without risk of delamination?
Hi. No, never used foil backed insulation for these applications. It’s a common mistake. Yes, use PIR, but you need to use boards with no foil. You cannot bond onto the foil. Not only that, the foil can create issues with vapour control / transfer in a warm roof situation.
Hi Im building a large timber home which sits on jackpads and timber beams, then the joists sit on the beams. Im planning on fixing OSB to the joists in sections and then flip each section over so the OSB is sandwiched between the beam and joist then insulate and ply floor. Basically to create a cassette. I have seen this system on youtube for a hot climate home, do you think this will be ok for a UK home? Thanks
Manufacturers and some installers in the UK still specify this method, using the foil backed PIR. It’s a horrible detail. Think about it. Why would you want anything that’s made of timber on the cold side of your insulation when you can use the correct insulation and bond your membrane straight on. No timber. No rot. No problem.
Do you have a link to a spec for this? Particularly the types of membrane on the top side? I'd imagine that GRP won't stick to the insulation so won't be suitable?
EPDM bonded directly onto PIR insulation with solvent based contact adhesive . Any PIR provided it has no foil backing. Tube fasteners and washers to secure the insulation. I don’t have a lot of experience with GRP but from what I have seen, EPDM is a much better application.
Fantastic video! Would love a part II with anymore you can think of
Great video once again!
Thanks again!
Timber frame cold bridging, strapping down the roof, particle board mistakes - very informative thanks for sharing
Thanks.
Excellent, thank you.
Thanks a lot.
Hi great video, although it been some time I have worked in construction management having come from the trades, so its great to watch a video that is well informed. A lot has changed so I am re-educating myself on some new products, and I have seen a few things on other videos that I question and so I like your point the regard to edpm @ 8:51 you talk about interstitial condensation due to EDPM being glued to OSB over PIR foil back. I have often thought about this. So your saying the the EPDM should be glued directly to the PIR. My only concern with that is how fragile PIR is but I get it, with the cold bridging and the foil and no ventilation in that area due to the sandwich of materials and the possibility for moister to build up from water vaper in the air and getting trapped between the osb and the pir layers.
I do have a question as I am planning to build a garden room next year, and was wondering how you would go about designing the base, the total area is 30ms, which will combine both a shed and the garden room. I wondered what your preferred method would be. I am considering both timber suspended or solid concrete. With a suspended timber floor giving 150mm for ventilation would you remove the top soil and lay a 150mm bed of hard core then dpm then the 150mm ventilation void. Or 150mm hardcore 50mm sand blinding dpm and 100mm of concrete with 100mm of pir on top for a floating floor?
Thanks
Hi. For the insulation, you secure it mechanically to through the deck to the joists. You never use foil backed.
Yes I will always go for suspended floor over concrete. Scrape land, no need for hardcore, DPM and then 50mm blinding concrete to protect DPM , and then as you say, your 150mm ventilated void
I think that Jerry meant like this: Regarding EPDM and condensation, yes, directly gluing the EPDM to the PIR insulation can help prevent that moisture build-up between layers since it avoids the issues with foil-backed OSB. PIR can be a bit fragile, as you said, but keeping it straightforward with fewer layers usually works better for insulation and ventilation.
About your garden room, I’d go with a suspended timber floor over solid concrete. Here’s my preferred method: scrape the topsoil, no need for hardcore. Then lay a DPM (damp-proof membrane) directly, with a 50mm blinding layer of concrete on top to protect the DPM. After that, add your 150mm ventilation void under the timber floor.
In England it is common practice to build walls off 'Egger Protect' flooring on garden rooms and also large cabins. Egger Protect is an expensive material so maybe is OK??? Just wondered what your opinion is on this, great video, it is a very good point you have raised about building off chipboard.
Hi. Yes, I understand it’s common practice by some. I see it also on a lot of popular RUclips self build and DIY channels. The reason they do it, I guess, is to make it easier to make their walls right angled, rather than using 345. It’s a terrible detail. You’ll hear the standard “I’ve been doing this for years and never had a problem” answer. Phone up a structural engineer, phone up Egger protect manufacturer as well, and ask if it’s suitable for taking roof point loads, and you’ll have your answer. Have you ever had your kitchen worktop swell up and fail when it gets moisture ingrained? What happens if the weight compresses the tiny air gaps in chipboard? Or part of the composite fails? Of course it’s a rare occurrence. If it fails.. will your builder come back to re build your investment at their cost…. Or pay you compensation? And if you’re doing it yourself…how will you feel if all your hard work is ruined? Why not just do it right in the first place?
@@build-better-things Yes I do get what you are saying, it is a brilliant point. I saw one RUclipsr build his own cabin with a glulam beam to create about a 5m open space, he had about 6 vertical timbers supporting it, all on the Egger Protect, he isn't a commercial builder though. It is a cabin on a steel frame with wheels with an apron cladding system. So the edge of this flooring could be a bit of a potential weak spot I guess.
9:07 I'm looking to add insulation to the external 2x4 walls on my first floor in the way shown in this diagram with the additional insulation to prevent cold bridging. Whats the benefit of using the OSB inbetween the insulation layers? Could it go on the inside of the insulation, directly under the plasterboard?
Great video!
The issue would be services and pop throughs. The beauty of frame construction is the integrated service void. Air tightness also might be harder. If you can live with that, I think it’s probably ok, but I might consider omitting it and using bracing instead to deal with the racking, after speaking to an engineer. You would need a reinforced breather membrane but I’ve done it before.
Excellent video, very clearly explained..! Hv u made a video for timber frame, if so pls confirm. I have timber frame on the 1st floor 5” thick studs. Will they be enough to hold a dormer loft conversion. Wht size should the studs be..?
Hi. I’ve made videos about attic conversion, dormer windows, and a load on timber frame. Just have a look at the play lists. I’m reluctant to give advice on timber sizing as it’s always project specific. Thanks a lot for your comment.
I take your point about not adding another OSB on top of a warm roof insulation. My question is, can rubber roofs be safely bonded to foiled backed PIR insulation without risk of delamination?
Hi. No, never used foil backed insulation for these applications. It’s a common mistake. Yes, use PIR, but you need to use boards with no foil. You cannot bond onto the foil. Not only that, the foil can create issues with vapour control / transfer in a warm roof situation.
Hi Im building a large timber home which sits on jackpads and timber beams, then the joists sit on the beams. Im planning on fixing OSB to the joists in sections and then flip each section over so the OSB is sandwiched between the beam and joist then insulate and ply floor. Basically to create a cassette. I have seen this system on youtube for a hot climate home, do you think this will be ok for a UK home? Thanks
Yes, cassettes are used all the time by the volume house builders. It’s a good solution.
The flat roof one caught me out! Ive seen so many drawings with a top skin of timber to grp onto? When did this change?
Manufacturers and some installers in the UK still specify this method, using the foil backed PIR. It’s a horrible detail. Think about it. Why would you want anything that’s made of timber on the cold side of your insulation when you can use the correct insulation and bond your membrane straight on. No timber. No rot. No problem.
Do you have a link to a spec for this? Particularly the types of membrane on the top side? I'd imagine that GRP won't stick to the insulation so won't be suitable?
EPDM bonded directly onto PIR insulation with solvent based contact adhesive . Any PIR provided it has no foil backing. Tube fasteners and washers to secure the insulation. I don’t have a lot of experience with GRP but from what I have seen, EPDM is a much better application.
Thanks!