In our new home, in the back of our closet the previous home owner had put that flimsy thin wood paneling as a wall in between the back of the closet and where the triangular part of the roof is about 5ft tall.

So behind that is a finished storage crawlspace area with insulation, plastic vapor barrier and the OSB board. The OSB boards do not meet flush to each other where there are corners, except the floor. It looks nice and is well done.

However, in the winter our closet is cold, like you can feel the air coming out when you go to grab a shirt. The summer (now) it's hot upstairs, more so in the closet. My question is, what is the best way to go about insulating this better?

I was going to go buy some insulation sheets, just FOAMULAR sheets, and install them on the other side of the closet "wall". I know that you shouldn't put more insulation over vapor barrier. Would this suffice in keeping weather temp out or is there a better way to go about this? Hopefully my description is good enough to picture.

  • Does your closet have a door on it? (You don't keep "weather temp" out--you keep heat in. Unless you supply heat to the closet it will always be cooler than the heated room.) – isherwood Jun 7 '19 at 17:55
  • Front of closet has doors on my side and my wife's side. A portion of the back wall of the closet can be lifted and slid to reveal the storage behind. That is where the that flimsy board paneling is to separate the storage from our closet. – BramblePelt Jun 7 '19 at 18:16
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    Maybe photos or a sketch would help with comprehension. Is the rest of the wall between your bedroom and the attic insulated, or is the attic insulation acting as the home's energy envelope? – isherwood Jun 7 '19 at 18:27
  • Where you only have plywood I would be adding foam board and using spray foam to seal any gaps, it may not take much to make a really big difference and the cost is minimal. – Ed Beal Jun 7 '19 at 20:34
  • When you are in the crawl space, At the low end of the roof pitch do you see soffit vents or day light. A vapor barrier should be facing to the inside of the house.,Adding foam to crawl space door will help and a good seal.And if roof is not insulated would explain the temp change. – user101687 Jun 7 '19 at 23:28

Better sealing is usually step one. You say a portion of the back wall can be lifted out of the way to access the storage behind. This makes me suspect the sealing isn't as good as it could be. (If you have a non-contact thermometer, you could point it at the edges of this removable portion to confirm, and compare to other areas of the wall. Otherwise, you could use you hand, and see if you can feel a draft; this will likely work better in the winter.)

As to how to fix this, you'll basically want some form of weatherstripping. This will probably need to be combined with a latch system to hold the access door shut against the weatherstripping, in order to provide a proper seal.

  • Some pics would help to better a good answer. – user101687 Jun 7 '19 at 23:14

Sounds like you have a knee wall 5 foot ,insulated on that wall .Air may be coming in through soffit vents. Build a same wall down low,12 inch in height. Insulate short wall. Add the foam backers to roof for air flow to ridge vent. Add the proper insulation 9 inch may be enough. Seal any air gaps. Add foam to door and a good seal.

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