Attic insulation "newbie"


Hello everyone,
I have just purchased my first house, and it is 80 yrs. old. My attic has NO insulation in the floor or the roof. I live in NY on Long Island and wanted to insulate the attic for $$$ savings. According to NY R ratings, I need R-48...My joists are 16" apart and look like 2x4s. I wanted to put down plywood to make some flooring, but if I put 2 layers of insul. (1 between the joists, and 1 perp. ) how do I put plywood down?
2 questions: 1. Is it worth doing? 2. What tips, resources do I need to make it a 1 time job and not require me to undo and redo the same thing because of mistakes?
Any help is appreciated.
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Rich wrote:

Is _what_ worth doing? Insulation or flooring?
Insulation is certainly a cost saving proposition. A house of that age and w/ no ceiling insulation may well have no wall insulation, either. I'd suggest an evaluation if you don't know. Check w/ your local utility companies -- they may well still have cost share programs and energy efficiency evaluations available for no or little direct cost.
As for the "flooring" in the attic over the insulation -- it is likely the ceiling joists aren't sufficient to support any weight, anyway, and laying them directly on the insulation to compress it will negate much of the insulating value. A small area might be doable by building a false floor, but overall, w/o further work and evaluation, I'd recommend against the idea of any large area.
As for tips, ensure you have adequate attic ventilation (probably not a problem w/ an old house, but never know, and is important in cold climes) to avoid condensation issues, the bane of insulation is air leaks/gaps.
For an overall effectiveness, the attic alone will undoubtedly help, but really need to evaluate the entire house, particularly for air intrusion/leaks. Windows, doors, foundation, crawl space/basement, etc., etc., etc., ... That's where the above energy-efficiency evaluations are of great value.
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dpb wrote:

Thanks for the tip...ironically, my basement is part of a 2 zone heating system, and retains heat very well.
My plan was to insulate the attic and use it for storage (hence the plywood option), but would it be smarter to insulate the floor with whatever R value will fit in the joists, plywood it up and then insulate the rafters on the roof? Would that allow for solid insulation AND make it available storage?
Thanks...
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Rich wrote:

...
W/ 2x4 joists, you don't have sufficient structure to support any significant load w/o doing something fairly significant to provide the load bearing support so my recommendation is still to forget the flooring idea entirely.
The effectiveness of the insulation split between a layer on the floor isn't as good as the single layer and by having the two separate layers you're adding to the possibility of creating condensation problems imo.
I think the only thing you can really count on being able to store in this attic space satisfactorily is a few empty boxes kind of thing -- there just isn't adequate support otherwise from the sounds of it.
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wrote:

IMHO, since it's not my house.
I would NOT floor that attic, the 2x4's sound flimsy for anything other than keeping up your ceiling.
Now for the insulation part, I have two guesses:
1. If I don't want to get access to the joists again (not planing on wiring, anything, ceiling fans, etc), I would dam out any non-IC fixtures (3" I think is required), and I would use blow in insulation, over poly.
2. If I do want to get access later, I would use regular batting, with vapor barrior down for between the joists. That will give an R-11 to R13 for x4 construction, and then go perpendictular with non-vapor barriored batting. I think you can get R-38 right now at lowes, just DEFEAT the vapor barrior. So 11(or 13) + 38 should give the desired 48 you want.
Now not an insulation expert, just sharing my option.
later,
tom @ www.Consolidated-Loans.info
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Rich wrote:

It is almost always worth it to insulate. Plywood is not necessary and may be undesirable. You just walk around on the joists or put down a few planks to give temporary walkways.

The best tip for cutting bats is to compress the cut line with a board to make it easy to cut. Since it is impossible to make a perfect cut, it is best to cut a bit long. It will save a few headaches. Most importantly, take care not to cover over any soffit venting your attic may have. Wear long sleeves, eye protection, and a dust mask.
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wrote:

ANY insulation is better than none, and the first 4 inches will do you as much good as the next 8. Start by sealing the hell out of everything, so you don't get air coming through the ceiling. Then put down insulation between the joists.
If you really have 2x4 joists, the chances are good that your ceiling isn't designed to support any load. Even light storage. In which case, there's no point in putting plywood decking down, and you can just go ahead and lay more fiberglass batting across the joists the other way.
If you find some reason to believe that the ceiling CAN support more load, then I'd put down 1/2" plywood, cover that with foamboard, and protect the foamboard with masonite. (if you're using the attic for storage) If you're trying to convert the attic space to living space, then you don't want to insulate the floor at all, you want to insulate the ceiling.
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Goedjn wrote:

Well, I just measured the joists, etc. and it appears that the majority of the attic is 2x4 construction and there is ~14.5" between the joists. Certain parts of the attic were raised up and floored ( I bet there isn't any insulation under there either). I am hoping that I can fill the joists with r-13 and then perpindicular layer another layer to meet the flooring. I might not reach R-48, but it will be better than nothing.
Anyone know anything about cotton insulation??? Like this stuff: http://www.environmentalhomecenter.com/shop.mv?CatCode=PRODUCT&ProdCode=COTTON_INSULATION
Thanks again for all the help.
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Rich wrote:

http://www.environmentalhomecenter.com/shop.mv?CatCode=PRODUCT&ProdCode=COTTON_INSULATION
Thanks Rich for that link. I was not previosly aware of that product. Definititely a premium insulation. Of course it's expensive but that's to be expected. I would love to work with a product like that.
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Lawrence wrote:

...
Why's that? Seems a product from a waste stream that doesn't require much other than shredding to create a new product should be pretty inexpensive.
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dpb wrote:

Have you seen the prices they get for used/distressed jeans these days? :-)
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dpb wrote:

People and companies always charge what the market will bear in order to maximize shareholder profits. It called supply and demand and is the basic premise of the marketplace called capitalism. A new product always cost more when it first comes because developers are testing the marketplace. Price is always determined by supply and demand and rarely by anything else and since this particular waste stream is a limited one a natural shortage is created as well.
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Looks like it would make a nice rodent nest. So soft and warm, mice would love it. I'd certainly do some research before hiding cotton nesting material in my walls.
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Edwin Pawlowski wrote:

That's a good point and one worth making. I know fiberglass is treated against rodents. I didn't keep them from nesting in my fiberglass insulaion. They got into the floor and ruined all of the insulation which had to be trashed. Now I have bit of a phobia concerning mice and I now go to great extremes to exclude them form under the floor. I am sure they would like the cottone even more than glass. Just saying, up north where I live the mice aren't too choosy about where they can manage to survive.
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Rich wrote:

With 2x4 joists I wouldn't even think of crawling around, unless you're 98 lbs., for fear of cracking the ceilings below (my attic has 2x6s and insulating has resulted in a few cracks).
So I'd suggest renting an insulation blower so you can keep a safe distance, rather than using batts.
And forget the plywood - don't even think about storage.
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