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Discussion Starter · #1 ·
I have a 1.5 story Cape Cod style home with a bedroom being upstairs in the "attic" space. There are two attic spaces on both sides of the bedroom both with access entries.
Upon purchase of the home, I installed unfaced R-30 in the knee walls on both sides. They just sit within the 2x4s. Recently, I ripped out all of the ceiling/attic floor insulation and installed more unfaced R-30 insulation. The attic spaces run very hot in the summer still. When I installed the insulation, I did also notice that there's no seal at the floor, which I understand should be my first step at stopping the air loss from the rest of the house.
I've been doing some research online and came across radiant barrier rolls, which is supposed to keep out most of the heat from the sun (which is when the attic spaces heat up). I've read that it's bogus and does not really work. So that led me into reading about possibly installing housewrap on the knee walls and attic floor over the already installed insulation to create an air barrier.
I'm very confused on what I should do at this point. I'm not sure if I need to install a vapor retarder or faced insulation in either or both of the knee walls and or attic floor/ceiling.
Also, to tackle the heat in the summer, I've thought about installing a attic fan that would suck out the warm air, however, I think it would only work on one attic space. A new roof was put on 3 years ago when I purchased this house and roof vents were installed to the very top of the roof (not in either of the attic spaces). It seems there is some venting to the top of the roof through the slope where the knee wall meets the roof, but the knee wall insulation I installed may be blocking some of that.
Also, I'm not sure if insulating my roof walls where the shingles are installed would make any difference.

After multiple videos, blogs, forums, I'm so confused on what I should do at this point, or if what I've already done is right or if the lack of vapor retarder will cause problems later on. Any advice would be greatly appreciated at this point.

One last note, my climate is Ohio, so it gets hot in the summer, and cold in the winter.

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37,499 Posts
Got a picture of the so called roof venting you have?
Did you spend the time looking using the search function on this site. There's at least dozens of other post on this one subject.
Location in your profile would be a big help with questions like this.
I've never once seen a cape insulated and vented correctly.
Really need a ridge vent to vent the whole roof not just a few bays.
Is there full soffit vents?

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I'll add to Joe's comments.

To start you should identify the best way to build or improve a cape and then incorporate as much of that as possible. I live in a cape so know the options very well.

Code requirements for insulation are considered absolute minimum, so determine what the building codes want to see and install more, if possible.

A vapor barrier and air sealing are two different improvements. The air sealing is at light fixtures and tops of walls. See link and is far more important than a vapor varrier. Paint can act as a good vapor retarder.

You do need vent space above the insulation on the slopes and low intake vents (soffits or other).

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