for years builders have been throwing up a vapour barrier willy nilly, not saying its right but I have never seen an architect request an air tight vapour barrier which is quite tricky and time consuming joiners on a pittance wont waste time unless your going to stand over them and watch. Steve roofer guy must have had some of his roofs fail in the past to promote this level of passion about vapour barriers and lets face it without his youtube chanel who would have known about the importance of a vapour barrier.

You’re welcome 😊

I always draw a sketch and measure the Exact locations and then mark them on the drawing so I can remark them on the ceiling after plastering.

Thanks, it is really about headspace 👍🏾

Good point lol I didn’t realise myself.

Thanks

Think he mentioned before that the issue is it takes up too much space Would probably be a bit cheaper and better insulated but still many draw backs

is that bad?

@@jamesdiver2183 Of course it is! The whole point of a vapour barrier is stop water penetration, if it's been punctured, then it compromises what it's supposed to do.

@@boo2yoo doesnt screwing the plasterboard puncture it too?

Hi Dean, It doesn’t, same way putting holes in insulation a doesn’t negate it. You will always have to have some level Of intrusion in the vapour barrier as there is no way around it but it Will do it’s job on 99% of the areas needed.

@@darrenthebuilder It is possible to wire it without penetrating the barrier by wiring surface on beams and noggins across if needed then covering wiring with second plasterboards over the first covering the gaps. Problem is of course the added expense of plasterboard but ensures the roof sealed.

You mean having two ceilings? And how to you screw your ceiling without piercing the VB?

​@@deanholloway7755 Wouldn't be worth the extra cost of effort and the issue is office buildings tend to be restricted to 2.5 meters total height. A vapour barrier with some holes in it is still 95% effective

@@darrenthebuilder My initial interest was and is a genuine request for an understanding of the use of the membrane. I am a qualified plumber ( not gas Safe ) and spark 17 edition ( too old to update now) and have had to build a single storey extension to the side of my house as timber frame due to covenants in deeds. I had to use cold roof due to further restrictions on height. Everything is restrictions these days. Anyway I had been looking at loads of videos such as London Roofing and Skill Builder etc and they all basically say cold roofing is a big no no unless you go to great lengths to get airflow and also scream about perforating the membrane. When you replied with the question I replied to your specific job and understand that point about screws which is impossible to avoid and can only be negated partially by using a sealer between boards and membrane. As you said that it's not as important as these other videos make out and indeed someone else has also commented as such I have decided to do as you have except for the size of the holes for the wiring. I shall be bringing the cable in the cavity and along noggins and drop them through so holes are maybe 15mm in membrane and board with sealer put into these holes to seal as best as possible. Obviously I am not using sunken spots but if I were they believe they make special ones for such cases. I like you and as mentioned above know you cannot put a ceiling up without putting holes in membrane but believe that as they go straight into the beams and are in effect compressed little moisture is going through there and will not be sealing. I would like to thank you for your initial video as it is the only one to not make a drama out of the problems of cold roofing construction and membrane integrity.

You don’t need that. Rafters are spaced at 400mm centres which is fine and standard for plasterboard edge. Just tape joints and skim 👍🏾

O dear another KZfaq warrior