Insulating a knee wall with gable vents
My knee wall is currently insulated with fiberglass R13 with the paper facing inside toward the drywall and nothing on the exterior or roof.
Unlike knee wall insulating how-tos that I’ve found, mine does not have soffit vents for the roof, only gable vents on each side of the house in the space. Is it possible to properly insulate the entire attic and if so, how (the roof needs to be ventelated, right?)? Or should I just concentrate on the wall and floor?
The existing wall insulation looks like it’s been there since the house was constructed 40 years ago and has a fair amount of dust (air exposure from the gable vents). Should I replace it or can I reasonably get away with just covering it?
Whether I replace or not, my plan is to cover the wall using 1/2″ polysteryne sheets and sealing.
Additionally, while there are no soffits, where the floor meets the roof is exposed. While I can see some existing fiberglass insulation, my plan is to seal those openings with foam and seal as well. Does that sound like the correct approach?
Thanks!
Replies
I'm having trouble picturing your attic configuration. Is it configured as shown below, but without soffet vents and with gable vents for each end of the two knee walls, plus an additional set of gable vents above the collar beams? If you don't have soffet vents, I don't see how you are going to get reasonalbe air flow without using a fan to pull air from one gable to the other.
Here's an expert rendering of the situation.View Image
It's a saltbox with only one knee wall and a full sized attic above it. The gables are actually square and not triangles as I drew them.
No soffits for the knee wall, only gable vents on each side (and similarly, only gable vents for the attic above it).
And in cleaning out the knee wall a few weeks ago I discovered that the gable vents were half-covered with old rugs (needless to say I removed them). *sigh* It's not my first time letting out a long sigh with some of the decisions the previous owners made with house!
So is the correct way to proceed for the knee wall as follows?
1. Don't bother trying to insulate the entire-knee wall enclosure. Just concentrate on insulating the wall and floor.
2. Get fans installed for the gable vents.
Should the gable vents in the "main" attic also have fans?
Thanks!
With a knee wall you either enclose the space and insulate the roof, or you ventillate the space and insulate the floor and wall. One or the other.
Often the choice is based largely on how it facilitates ventillating the "attic" space and any slant ceiling between knee area and "attic".