01-25-2010, 12:15 PM
I guess that explains the "vapour barrier goes on the warm side" rule of thumb. Either way (moisture inside the building or out) the barrier prevents the moisture condensing inside the insulation as it cools.
Using a closed cell insulation (extruded/expanded styrene, or spray foam) eliminates the need for a vapour barrier, and the associated guessowrk to figure out where best to place it.
By the way, I understand that several good coats of latex paint also count as a vapour barrier in situations where it would be impractical to retrofit one (e.g. old homes with plaster walls and no insulation).
Andrew
Using a closed cell insulation (extruded/expanded styrene, or spray foam) eliminates the need for a vapour barrier, and the associated guessowrk to figure out where best to place it.
By the way, I understand that several good coats of latex paint also count as a vapour barrier in situations where it would be impractical to retrofit one (e.g. old homes with plaster walls and no insulation).
Andrew