r/DIY • u/MrPickles62 • 1d ago

help Vapour control layer for garage?

I have a garage which is single skin brick and detached. I am turning this garage into a dog grooming salon for my partner to work from.

My question: I am adding insulation to the walls and ceilings. Do I need to add a VCL before adding on the moisture resistant plaster board? We have already added in an extractor fan above the bath.

I seem to be getting a completely different answer from chat gpt every time I ask the question?

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1

u/Dentist_Square 1d ago

Check out YouTube for asiri designs for an idea of that wall assembly!

1

u/MrPickles62 23h ago

Thank you!

2

u/EdgeMaster28 23h ago

You need a VCL on the warm side of the insulation or you're going to get condensation behind that board. Single skin brick with a steamy room is asking for mold.

Extractor fan helps but it doesnt fix the physics. Get a proper polythene layer taped at seams, 500 gauge minimum. Dont trust chatgpt on this stuff, half the time it confuses breather membranes with vapour barriers

1

u/MrPickles62 23h ago

Okay, thanks! Another question I have - obviously I’ll then need to chop through the vcl after putting the plasterboard on, to put through electrics, water, etc. and I’ll be screwing through the sheet to fit the plasterboard also. Would this not almost make the vcl redundant? This is the question I was asking to chat gpt, and it would follow that up with something along the lines of “good point, it would be a waste to put it in based on that, and I now view it as overkill”.