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
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
Any help is appreciated.
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
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.
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?
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.
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,
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.
tom @ www.Consolidated-Loans.info
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.
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.
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:
Thanks again for all the help.
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.
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.
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.
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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