Retrofit insulation for converted attic
Our last frontier to conquer in our house is to maybe redo the upstairs. It’s an 80 year old house with an attic that appears to have been converted in the early 90s. It’s ugly, and cold in the winter/hot in the summer.
It’s one room with about 4′ knee walls on each side insulated with fiberglass, then the roof in the center, which is old 2x4s with fiberglass and that foam vent, so maybe 3″ of fiberglass for most of the ceiling.
This is clearly inadequate.
I’m not sure if/when we’ll get to redoing the upstairs, but just for planning’s sake, what would be the best options.
The options I’ve come up with:
– we’ll need a new roof eventually. Tear off the roof, and insulate under (or over) a new roof deck
– tear out all sheetrock and insulation from the inside, foam it all, put new sheetrock back up
– leave sheetrock (or maybe remove sheetrock but leave fiberglass) on ceiling only, add 2″ XPS insulation to interior, then re-sheetrock.
Any merits to those ideas? Any better suggestions?
Replies
bump
I'm just sayin'
Sounds like you have a hip roof? A few years back we gutted our finished 3rd floor to try to address some ice dams that were causing leakage into the house. I'm in Syracuse, NY. I had similar thoughts as you (tear off roof and insulate from above and avoiding the mess inside, installing foam over sheetrock and then re-sheetrocking, or gutting and start over). I didn't do the roof tear off option because most of the roof was in good shape. If you need a new roof, maybe it's worth considering. The foam board insulation option would have reduced headroom dramatically before getting to the code-required insulation (R-38 I believe here). So we demo'd and redid everything. I had closed-cell spray foam installed and turned it into an unvented roof. Generally it's been good- warmer house, much less air leakage (almost 50% reduction), and fewer ice problems. The only issue now is excessive moisture in the house.
As for you, I think the roof tear off while seeming to make sense would be difficult. I doubt the insulation install would be as good as if it were done from inside and you'd have to tear off parts of the roof decking- something probably not necessitated just for the roof replacement. The foamboard reduces headroom like I said and then you need mega screws to hang the sheetrock because you're reaching through maybe 6 inches of foam to hit rafters. Insulating from the inside is probably the best option though maybe you don't need to go the spray foam route. It is expensive. If you have a hip roof, they're nearly impossible to vent with the finished room's sheetrock installed directly on the rafters so the foam is the only way to go for those situations.
Just my experience to consider. Good luck.
Brian
gable roof, but I think we have the same issues.Basically, we have maybe 3" of fiberglass insulating the ceiling upstairs. So, I suppose ANYTHING we do is going to improve upon that. ;o)In my gut, I know foaming is really the best option. We'll get it priced out come spring and see if it's worth putting the $$$ into it. With the market the way it is, it might be a tough call to put too much more into this place.
I never asked how much headroom you have. If there's enough I suppose you could upgrade the insulation (either fiberglas or foam) by adding to the rafter depth. With a gable roof, the venting is much simpler than my situation. While the foam is high performance, so is the cost and that makes it a last resort in my opinion. (Ours totalled about $7,000 for 6-inch-thick layer over 1,100 square feet.) Maybe consider gutting and sticking with conventional insulation (fiberglas, cellulose, and/or foam board) and a vented roof deck. This would mean losing headroom compared to foaming but maybe not a problem in your situation.