My master bedroom is above my garage. There is one part of the bedroom that has a cathedral ceiling with knee walls on both sides. There is no attic above this area because the drywall goes up along the ceiling joists. This ceiling is insulated with R19 insulation. The 2 knee walls are formed from the sloping roof in this area.

I also have a fairly narrow front porch that runs the length of the house. The porch has a roof that creates a knee-wall area along the 2 bedrooms at the front of the house. This area attaches to one of the knee wall areas in my bedroom.

There is no ventilation in any of these knee walls areas. There are no soffit vents (or porch ceiling vents in the front porch roof), and there is no way to run any type of venting up to the main attic or to the roof since there is no attic in these areas. There is no way for me to install gable vents, either.

I have insulation along the back of the interior walls in these areas, but I plan to replace it with a higher R-value insulation. Should I insulate the soffit areas (and the front porch roof area), and should I insulate the ceiling joists in these areas, as well?

Any help regarding insulation in these areas would be appreciated. There is no way to run any ventilation, though.

Edit in response to answers:

Yes, I could add soffit vents for intake in these areas, but there is no way to access the attic for out-take venting. Adding roof vents in the areas would look strange and unsightly from the front of the house as these areas run on both sides of my bedroom window which faces the front of the house. Adding a roof vent to the roof area of the front porch would also look very strange and unsightly from the front of the house. The same is true for gable vents. I would have 2 gable vents on the sides of my bedroom window at the front of the house, and, they would only end up being about a foot off of the floor in these storage areas.

So, should I insulate the ceiling joists and soffits in these areas, or should I just insulate the back of the knee wall?

  • There is always a way to run ventilation, usually several ways.
    – Ecnerwal
    Jul 20, 2015 at 16:25

1 Answer 1


I'm having trouble visualizing the whole layout. That said I also have knee walls and sloped ceilings. I was able to force attic baffle vents between the insulation and roof by taping them together, then pushing them up with 1x2 sticks. It's not perfect I'm sure, but does allow some ventilation from behind the kneewall to the main attic. Of course, I have soffit vents at the top plate behind the kneewall and a standard ridge vents at the top of the roof.

If you really can't add soffit or ridge vents maybe consider making it a hot roof and add more insulation on the actual slope ceiling/roof, either interior or exterior (if a new roof is in order anytime soon)

  • I can't quite visualize it either, but are you sure a ridge vent cannot be added?
    – Evil Elf
    Jul 23, 2015 at 14:29
  • The following picture has a roof line very similar to mine, one long gable over the main house, a lower gable over the side load garage, and then a 3rd gable that faces the street. There are knee walls on both sides of the window above the garage. The knee wall to the left of the window connects to the knee wall that is formed by the roof over the front porch.
    – peggy
    Jul 23, 2015 at 16:42
  • monsterhouseplans.com/images_plans/13-127e.jpg The ceiling goes up to the peak in the part of the bedroom where the window faces the street. So, there is no attic access there, and the knee wall areas do not have access to the main attic, either. I think I will just insulate the areas very well and go from there. Thanks.
    – peggy
    Jul 23, 2015 at 16:52

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