Silly questions that keep you awake at night #182
If you're fitting Celotex backed plasterboard, how do you maintain the vapour barrier between the sheets? With separate layers, I'd foil tape the joints and stagger the plasterboard, but you don't have that option when the two are stuck together.
You don't. Foil taping us there when you have BIG gaps like studwork, and also to make it airtight.
plastering will do the airtight bit. And the gaps are not large enough for any serious vapour intrusion.
Remember vapour and damp control is not about perfection any more than insulation is. Its about making sure that gross and massive condensation or damp build up over long periods does not occur faster than it can evaporate.
The key is to have pretty resistant layers on the warm side, and pretty breathable layers on the cold side.
Neither have to be perfect. As long as the dew point is not gone below, there will be no condensation. As long as there is some escape for damp warm air when its warm it wont get cold later on and condense.
Oh, call me old fashioned, but I cut the Celotex carefully so that there aren't "big" gaps at the studs - by "big", I mean anything over about
2mm, which would get infilled with offcuts anyway. I always aim for a friction fit, whereas some seem to rough cut and infill with tubes of expanding foam.Must be my OCD that controls me taping everything up then!
Regards the original question, idle curiosity now satisfied thanks.
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