I have leftover insulation from doing my basement, little bits and pieces.
In between the joists on my basement ceiling it is insulated with vapour barrier already from when the house was built.
Will condensation form if I put all the extra pieces against the vapour barrier on the inside of the wall but do not put a second vapour barrier? Or will it be fine and help my house stay better insulated? Or is it a complete waste of time.
It just seems like such a shame for all these smaller pieces to go to waste.
Best Answer
Insulation is always installed as such:
Warm side | Vapor/ Moisture barrier | Insulation | Cold side
You ONLY want a moisture barrier between the warm side and the insulation, because warm air holds onto more moisture than cold air, and when warm air meets cold (air, wall, whatever), the air has to let go of that moisture as it cools, forming condensation. The moisture barrier prevents that moist air from getting into the insulation where cold and warm meet.
If you put insulation on the wrong side of your barrier, the moisture will form in the insulation, and as Shirlock said, if you create TWO layers of barrier, you create a potential moisture trap.