Should I replace blown in insulation when installing attic floor?

My house has an unfinished attic with a partial floor (maybe 1/8 of the attic currently has a floor). I am quickly running out of storage space and would like to put down some simple plywood on top of the floor joists to serve as a floor for storage. There is currently blown in insulation through out the attic.
Do I need to remove the blown in insulation and replace with rolled insulation? I have heard that blown in insulation works best when it is not compacted, and putting the plywood on top would compact it. But I have also read some posts around the net that suggested that it was not necessary to remove the blown in insulation.
Any thoughts or ideas?
Thank you!
Mike
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On Thu, 1 Jan 2009 11:51:51 -0800 (PST), Mike Daniska

     If you are compressing it say one inch out of eight, don't worry. If you are compressing five inches out of ten, then I would remove most of it that is over the level you will be putting down the floor.
    BTW adding the floor will increase the insulation a little.
Good Luck
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Is it unheated and open to air, wher do you live, what Heat Zone. If inheated and open the floor is insulating your home, in my area zone 5 about 12" is minimum needed, maybe 17" optimal
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any insulation you press down to the thickness of the ceiling joists will assume the r-value of that thickness.
s

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On Thu, 1 Jan 2009 15:51:32 -0600, "Steve Barker"

No. Compressed insulation will have a lower R value. It is the trapped air that insulates.
Jim
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If anything you would be wanting to *add* insulation to the attice which is the point of the greatest thermal loss. My blown-in was done by the previous owner and on top of the glass insulation. Over the past 25 years it has settled and I have rolled out new batts perpendicular to the joists. Now, if I were in your situation and wanted to create storage for light loads in my attic I would make 2x4 standoffs to a height just greater than the insulation that you have or intend to put down in the future. I would connect them with 2x4s and top with 3/8" CD ply. JAT Chuck
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C & E wrote:

Excellent idea.
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Yeah, except for the fact that in many attics, you don't have much headroom to begin with and taking 4 inches just makes it less usable.
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On Jan 2, 7:50am, snipped-for-privacy@optonline.net wrote:

Usable, its an unheated attic for storage not sleeping.
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C & E wrote:

Andy adds:
A good idea, and not very expensive or hard to implement..
Remember tho, that NOTHING stops air from moving like a solid barrier. When you put the plywood floor down, it makes a solid barrier on TOP of the insulation, which means that air will no longer waft up thru the insulation...
So any R factor you lose by comressing the insulation will be offset by the fact that you are putting a solid barrier on the top side, which means there will be practically no air circulation..... In my opinion, the decrease in Rfactor, if there actually is a decrease, will be negligible for only a couple inches of compression. In fact, it might even get a little better, but one would have to experiment to know for sure....
If air circulation was NEEDED in the insulation to prevent moisture buildup, that might cause a problem , depending on which side of the insulation the high moisture side is on. But it probly wouldn't bother you much in the technique you are suggesting...
Best of luck on your project.
Andy in Eureka, Texas ...... P.E.
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Ideally remove all the existing insulation and replace with expanding closed cell foam insulation R7 per inch.
the existing fiberglass is likely R3 per inch
the expanding foam seals all the little air leaks so its a far better insulation
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Wow! Thank you for all of the suggestions and help! I am going to have to bookmark this group :-)
I think I am going to take a look at going the simple route with some plywood on top of the blown in insulation in a small part of the attic, just to see how that works out. Also, just FYI (probably should have mentioned this first), my home is new construction built in 2005. The entry way to the attic is from my bonus room, and there is a small portion that does have a floor. This floor seems like it is higher than the floor joists (like what C&E suggested about putting down 2x4s). I don't need anything fancy, just some floor to store all the junk accumulating in the rest of the house. Of course, that is probably a story for another Usenet group :-)
Thank you again!
Mike
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Then in that case, simply drill some holes here and there?
David
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On Thu, 1 Jan 2009 11:51:51 -0800 (PST), Mike Daniska

Get rid of stuff. Nothing likes attic summer heat anyway.
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