Retrofitting old home attic with hardwood floors

erinmnSeptember 30, 2004

Hi, here's hoping I get some good ideas. I live in an 80 y.o. bungalow in Mpls and my heating bills were extraordinary last winter. The biggest part of the problem is my extraordinarily inefficient 80 y.o. gas-fired gravity furnace. I get that, oh how do I get that. But I can't replace it yet, I'm still broke after moving last year. So I'd like to better insulate the attic. My house is almost a storey and a half, there's 6' headroom at the peak of the attic and it has halfway decent hardwood floors. Someday I'd like to expand up there since I only have 800 sf living space. The attic ceiling is uninsulated. I can see through the gaps in the floor that there is some blown in (likely cellulose) insulation under the floor. Is my best bet to try to pull up some floorboards to pump in more cellulose? (Ugh) Or should I insulate the rafters with fiberglass batts (and have to heat the attic space...)? Or could I get those 2 inch thick foam boards and lay them on top of my attic floor every Nov-March (so the cats can still play up there in the less inclement months)? Are they a big fire hazard? Please, any ideas? Thanks!

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Actually, this question is probably better suited to the heating forum. I'll bundle it off to there, but am happy to see what other answers I might get from the energy-wise! Plus, I'm willing to solicit input on what to do with my gravity furnace... (with its asbestos-wrapped arms)...

    Bookmark   September 30, 2004 at 12:36PM
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Get an energy audit via Xcel or Centerpoint. You might be surprised at how efficient your furnace actually is. I suspect they will give you a long list of energy saving things that you can do before even thinking about replacing your furnace.

    Bookmark   October 13, 2005 at 12:46AM
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I'll ditto that there's likely lots that can be done that don't involve the furnace replacement . . though that should still stay on the radar screen.

Being an older place it is likely pretty loose . . infiltration that is . . drafts around windows, sill, all over the place . ..and may not have any insulation in the walls etc. Blown cellulose could help a lot if that's the case; installed from outside via holes drilled.

You need to be careful about insulating the attic area . . . if you do so, you must allow for ventilation under the roof sheathing / boards . .. if not; you will almost surely guarantee yourself ice dammming and the attendant damage. I think a slick way to help yourself out would be to use rigid foam insulation; spaced AWAY from the underside of the sheathing by about 2". Cut to width between rafters; it can be "squish" fit in there and will stay put on it's own. The good rigid foams are ~ R-7 per inch if I remember correctly. Additional insulation in your ceiling would help too no matter what; and it's relatively easy to do. By the way; I'm curious your "UGH" when you mentioned cellulose . . it's dusty to deal with; but it's excellent insulation and VERY environmentally friendly . . I used nothing BUT that in my new construction. It WILL settle after installation; but remember that the R-value is base upon SETTLED density. And you don't "pack" it in . . . let it settle. Usually you get free use of a blowing machine when you buy so many bags . . . a bit messy but definately a do it yourself thing.

I've seen a lot of older houses built with nothing BUT flooring on the joists; leaving LOTS of places for air infiltration from the basement. Again; rigid foam can be fit between the joists and make your floors a warmer by limiting losses DOWN through them, as well as limiting direct heat transfer as well.

Window and door weatherstripping can be of great help too; even the best modern windows are pretty much R-crap compared to practically ANY wall; but a direct air leak can lose a lot through a winter . . . . and a lot of little gaps adds up to the equivalent of leaving a window open year 'round . . .

Good luck . . .


    Bookmark   October 13, 2005 at 6:13AM
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Wow, this was something I posted last year, surprised to see it resurrected like this! Thanks for the new postings, but I'm afraid I had to take matters into my own hands and I ended up using fiberglass batted insulation laid on top of the attic floor. It really helped with the bills and I had no ice damming problems.

Bob, the "ugh" related to having to pull up flooring in order to properly blow in cellulose. I have nothing against cellulose. I've decided against replacing the furnace as I'd have to replace the asbestos-wrapped huge ducts as well and that's just prohibitively expensive and risky. I'm going to install a small gas stove upstairs to be the primary heat source. House is small enough that I can cover living, dining, and bedroom with one small stove. Installed electric heat mat in bathroom under new tile floor and will be putting another in kitchen. This way the old inefficient (and the gas co estimated it's at 45% efficiency when I had them out to check it SuzyQ2! Yikes!) furnace will be just a backup.

I'm loathe to now tack on a question about insulating the walls as Bob suggested. I've been torn about it. Do people recommend it even if one has knob and tube wiring and a stucco house? I wonder if the potential risks (knob and tube, dampness?) outweigh the (somewhat useful) insulating effects gained by the air space in the walls? Perhaps I'll get some answers next year? LOL, I have enough on my plate for fall 2005 anyway! But thanks.

    Bookmark   October 13, 2005 at 10:34AM
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