I’m a DIY’er in a newer, pretty well insultated ranch house in Iowa. We have geothhermal and very low heating/cooling costs. I’m planning on getting into the attic as soon as it warms up a little to plug any holes I can find (from electrical, plumbing vents. etc) – what can I say, I’m cheap and I’d like even lower heating costs!
My question is about my interior walls that run up into the attic. My house has ceilings of various heights. Kitchen and some bedrooms 8′, living room 13′, daughter’s bedroom 10′.
My interior walls are 2×4. It occurred to me that the interior walls that run above 8′ are basically like exterior walls? What I mean is that these walls have 1/2 inch drywall on the interior and 3 1/2 inches of fiberglass insulation on the back side, open to the attic and the cold. It’s been a while since I looked but I don’t remember seeing any plastic vapor barrier or kraft paper.
My exterior walls are 2×6 and I have deep insulation in the attic but these ‘tall interior walls’ only have minimal insulation. Is there a good way to increase the insulation levels of these walls? I can’t picture how to build these walls out farther to add more insulation. I probably have about 70 linear feet of these walls.
You guys always seem to have good ideas.
Thanks.
Replies
I'll stay out of the debate over if and how to do vapor barrier after the fact in that situation.
However, as far as insulation goes, in new construction I do those areas with r-19 'glass batts held in place with housewrap stapled to the studs loosely enough so that the insulation can fully expand. It works well and goes up effeciently.
Should work in your reno also.
j
thanks, that sounds like a good way to solve the problem.
Have 2 lb spray foam sprayed in these cavities. Its an air barrier, vapor barrier and R-6 per inch insulation. doesent get any better than that
Rumble, that would be my ideal if cost were no object but unfortunately spray foam's probably not in the cards for now.
hawk
I would go up there with 3/4 or 1" Dow board or Tuff-R, plastic caps and great stuff.
I would stay away from foil faced. I think you want your vapor barrier on the inside. If you don't have a vapor barrier there then just let the moisture move. I am assuming your ceiling doesn't have a vapor barrier either. so these walls aren't much different.
Move the blown in out of the way. Cover the walls with the styro sheathing and foam the corners and the seams.
It helps to leave a gap when installing. It makes it easier to foam.
I would do it now. It would be very comfortable up there now.
If you wait for summer then you only have a couple of hours in the AM before it gets very warm up there.
Rich
Rich, I hadn't thought of using foam board. Are you suggesting to sheathe the 'outside' of the wall with the foam board, nailing it to the studs? If so, that would be easier than my first thought of what you were suggesting - to fill each stud bay with a piece of foam board and then replace the fiberglass.
You are correct, there is no vapor barrier in the ceiling. Adding foam board to the outside wouldn't cause any vapor barrier problems?
thanks
hawk
sheathe the 'outside' of the wall with the foam board, nailing it to the studs?
Yes that is what I am suggesting.
Adding foam board to the outside wouldn't cause any vapor barrier problems?
Stay away from the foil faced and you should be fine. Dow board is somewhat permiable. Very low but still not vapor tight.
Some Tuff-R is fiberglass faced.
Go hawks
Rich