How much insulation is too much?

[Christopher Nelson]

I have a split level house with a bedroom on the top-most floor. It might have been "attic" space when the house was built but was finished when I bought it. The room is cold in the winter and hot in the summer even though it's straight above the furnace with a fairly straight duct leading to it. (The kitchen is on the first floor, above the furnace and below the bedroom.) I imagine part of that is bad air return but the walls that run parallel to the ridge line are around 4' high and are 2x4 construction with one layer of pink fiberglass insulation. The outside of those walls (near the eaves) is fairly easily accessible and I wonder if it's worth adding 4" or 6" of fiberglass. Any thoughts?

[HeyBub]

Sounds like a classic case of insufficient insulation.

A. It can't hurt. B. It won't cost much. C. Is it air tight? D. Sounds like you're talking walls. What's up with the ceiling?

[ransley]

Where are you, what Zone.

[clare]

You want R60 in the "atic" or ceiling if you can.

[Steve Barker]

Anything past r49 is over kill unless you're in the tundra.

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[Phisherman]

I put 2X the recommended insulation in my attic. It lowered my cooling/heating bills. The best thing was that I did it 18 years ago.

[hrhofmann]

You don't say if there is any ventilation in the spaces around the bedroom that you are proposing to insulate

[trader4]

Also worth noting is that fiberglass insulation only works to the intended R value if it is uncompressed. Trying to stuff 10 lbs of crap into a 5 lb space doesn't work. The insulation value is based on the trapped air contained in uncompressed insulation.

[clare]

Up here in (southern) Ontario they are recommending minimum R50.

[Chris Nelson]

I figured.

True.

The area I'm insulating? It has some ventilation.

Yes, I have ready access to the walls. Part of the ceiling is sloped along the roof and some is flat. I can't easily get above the flat ceiling. It doesn't look well insulated. The only way to do that, I think, is to pull down the ceiling, put up insulation bats, and put the ceiling back up. Probably a good payback but more work than I want to do right now. I can get to one end and might blow insulation in but that wouldn't be easy either.

[Chris Nelson]

Near Albany, NY. No idea what zone that is.

[Chris Nelson]

Well, with ~4" of fiberglass uncompressed between studs I have ~R16 right now so adding seems good. My thought is to roll out 6" fiberglass horizontally (that is, parallel to the floor), stapling the top edge to the studs.