OK, now about attic insulation...

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My attic is full of insulation that looks like raw cotton (NOT rock wool), way higher then the tops of the joists. I want to lay flooring down so I can have some storage space. Do I pack the insulation between the 2x12's, or remove the excess? I'll be laying down 5/8" whatever
thanks, steve
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I dunno, mashed-down insulation doesn't work so well.
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Steve Kulpa wrote:

You would remove, never pack.
Next question. Do you know if those joist are designed to carry additional weight??? Not all attics are framed to accept any additional load. It may not be wise to plan storage of any kind up there.
--
Joseph Meehan

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Best way is to add strips to top of joists or nail extensions to side of joists. But it is up to you if you want to reduce the insulation thickness. I think compressing it will reduce the effectiveness more than removing part of it will.
Don Young
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I saw an ad in a catolog for racks that looked like ladders for storing stuff in your attic. I assume this is the same idea. The attic might be a good place to store EMPTY boxes for stereos and stuff. I wouldn't store anything heavier than that up there.
Randy R
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Even though his joists are 2 x 8's? That's as much as I have under my first flloor, including the baby grand piano.
What about all these people who finish their attic and put in furntiure. What makes their attics more suitable than his?

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wrote:

Empty boxes could sit on top of the insulation without compressing it too much. Anything else and I would also worry about how the heat would affect whatever you stored up there. My attic is well over 100F during the day in the summer. My parent's house had a finished attic, and they also had an extremely high heating bill during the winter. Before they left that house, I (and my stepfather,) thought they would save a lot by insulating the attic. This was a very old (70+ years old,) house with little to no insulation so anything would have improved it. I suppose as long as the attic was kept closed with an insulated attic door and some kind of reflective insulation between the trusses, you could put in a floor without compromising your heating and A/C efficiency too much. I haven't researched this too much, so I don't know how effective the reflective foil backed insulation (or paint?) is in insulating the attic itself.
Randy R
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Well, I think his plan was to figure out what to do with the excess insulation (compress or remove) and then put a floor in, so tthat by the time he was putting the floor in, there wouldn't be any compression..

Heat sounds important. No one else mentioned hea or coldt. That's part of what confused me.
I have a roof fan in my roof, and I don't think the attic gets more than 10 degrees above the outside temperature, which on rare days is 100, but mosly cooler. It also gets cold in the winter....I shouldn't have left that lava lamp up there.
But there are a lot of things other than cardboard boxes that can go in a hot and cold attic. If it turns out they dry out and break, then you can throw them away, but a lot of people would have to throw all of those things away for lack of a place to put them.
I hade my mother's bathroom scale up there for several years, and it was as good when I bought it down as it was when I put it up there. Also a chandelier, which already needed a couple fo the plastic tubes replaced. Also some metal auto parts, bulky things that would take up a lot of space in the basement.
My amplified antenna has been up there for 15 years and as hot as it gets, it still works fine, although maybe that plastic is designed for hot attics.
I'd have to go up into the attic to remind myself what else is up there.

Why would a floor compromise the heating or AC at all? Do many people have insulation sticking above the joists. My house didn't have much, but the first owner put in pink fiberglass batting, that is about as high as the joists. Should there be more than that?
In fact, the insulation traps air, but a floor that doesn't have cracks will trap the air too, even better than the insulation. There are crooked ways for hot air to rise through insulation, moving this way and that. If instead of plywood, he used thick T1--11, that stuff has interlocking edges that could make a floor rather free of cracks. (don't know how strong the stuff is, however.)

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My understanding is the opposite: that for a given thickness, a greater density of material insulates better. Conversely, for a given total weight of material, a lesser density (greater thickness) also insulates better.
Cheers, Wayne
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Wayne Whitney wrote:

Wayne has it right. Although compressing a given weight of insulation to a lesser thickness reduces total R-value, compressing the insulation increases the R-value per inch of thickness.
Assuming the joists can take the weight, you are best off adding thickness to the joists to keep the total insulation thickness. If you must resort to reducing the insulation thickness, then compressing the existing insulation is better than removing some.
Ken
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So you like throwing your money away.... Let me know and I can come by with a wheel barrow. Removing the insulation will increase the heating and cooling bills. As others have said verify that your attic structure can support the weight FIRST.
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Thanks for all the replies! No, I don't like throwing money away, just doing things properly. Turns out they're 2x8, not 2x12 so maybe I'm SOL on this one. Here's a photo of the insulation for those who asked:
http://www.geocities.com/stevekulpa/temp/insulation.jpg
guess it's time to talk to the builder.
Would it be better if I built shelves between the roof rafters and the ceiling joists do distribute the weight between the two? I really need some storage space and this attic is huge! Such a waist of space imho. look for yourselves:
http://www.geocities.com/stevekulpa/temp/attic1.jpg
Plus there is a pull-down ladder in the hallway so I guess I 'assumed' the attic was usable.
thanks again, steve
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You've got 8 inches of insulation between the joists and adding flooring will give you another half to 5/8 inch with some insulation value and better airflow blocking.
Don't pack it down too tight and I think you're fine.
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Steve Kulpa wrote:

Most attics are built to handle 25psf, so a small amount of storage is fine. Add height to the existing joists, or consider running new ones at right angles to the existing
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I guess to be save I should put any shelving over load-bearing walls too.
steve
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THAT'S where you put the HEAVY stuff -- as near as possible to being over load-bearing whatever (walls, columns, ...).
Just like if you're going to put a bunch of heavy stuff on a table (temporarily), you put it over a leg.
Likewise if you're going to (make sure wife isn't watching!) *sit* on the table or whatever. :-)
David
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Don't be discouraged too easily. Five-eighths plywood over 2X8s should be OK for storage as long as (a) the span is not too great (i.e., the 2X8 joists are no spanning a huge distance between walls) and (b) you don't put too many pianos, safes, lead smelters, etc. up there. Lots and lots of people have attic storage with no more than that. If you have normal size rooms under the attic, you shouldn't have to worry. Also, if its overloaded, you might notice some springiness or sagging when walking around up there, and/or get some cracks in the ceiling below. Not fun, but not a disaster either.
Looks like a well-insulated attic. Putting down 3 or 4 sheets of plywood for storage will decrease the R-factor some but not a whole heckuva lot, since its only part of the area, and the covered areas will still be fairly well insulated. You could take a broom and sweep the excess insulation from the area to be covered onto the uncovered area. -- H
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Looks like blown in fiberglass.
You would be stupid to remove it. Wear a mask if you do.
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G> Don't be discouraged too easily. Five-eighths plywood over 2X8s should

If you screw 5/8 plywood to those 2x8 rafters you're going to seriously increase the strength of the ceiling. Unless you are storing something very heavy up there, I don't think there is going to be any issue at all.
Anything you put up there (lets say a chest with clothing) will add to the insulation value. Instead of 12 inches of loose insulation, you have 8 inches of loose insulation, 5/8 inch of plywood and (in places) 2 feet of closed container. Sounds good to me.
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I know what you mean, my attic is just as big, maybe bigger (3 bedroom ranch.). I wish I had easier access to my attic other than the ceiling hatches in a closet and the garage. When the antenna installer opened the trap door in the closet, there was more than a foot on insulation covering it.
I like the idea of extending the ceiling joists and/or using 5/8" plywood for a floor. The ceiling will be a little stronger the closer you get to the walls also.
Randy R
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