This is where I am with my small 2m x 3m timber framed garden room. Originally I wasn't going to install a separate VCL and instead rely on fully taping up all my foil faced insulation. However the PIR boards I bought were second hand and many of them are pretty beaten up and punctured. I know it can still be done, but to do it really effectively as a VCL might require skill and patience I don't have. I will still have a go but now intend to follow up with polythene VCL sheeting. Can anyone point me to some written or video guide for doing this, as I really don't know the technique. I also have some basic questions:
- I believe 1000 Gauge is usually advised, but in my case is 500Gu or less acceptable seeing as it's just a belt and braces thing over the Kingspan PIR? Something like this 125Mu roll from Wickes: Polythene Vapour Barrier. Is the thicker stuff easier to use and put up? Also, I've found some other sheet I want to use (because it's clear), but it's not UV stabilised. Does this matter? I know it won't see any light, but does it potentially go brittle anyway?
- Would you normally use a staple gun to fix it to the timber studs every 200mm? Or is it possible/better to use just a Double Sided Butyl Tape onto the studs and them stick the polythene down?
- How do you deal with seams? Do you have to extrude both edges and fold them back down onto themselves and tape or staple?
- Finally, should I tuck the bottom of the VCL under that DPM under the screed and tape it down, or drop the VCL down over the DPM, or in fact fold both edges together and tape, as above?
I can't seem to find a tutorial about any of this, so if there is one, please point me in the right direction. Thanks!
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