Adding additional [attic] insulation


Old 12-28-05, 08:10 AM
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Adding additional insulation need advice

I have an 18 year house and want to make sure all my heat is not flying up through the attic. Attic has batt insulation appears to be R 13 or 19 canít tell since its matted down alot. I have about 7.5Ē between 2nd floor ceiling and top of attic beam. My region says r49 now is the standard, i donít know if i can get it that high but would like something in the R30ish range.

So if i assume that i currently have R19 which is matted down and depending on area has about 1-3Ē of a gap from the top of the insulation to the beam. I plan to fill in the gaps with cellulose insulation to the top of the beam. This will fill in all gaps and also get all of the insulation to the top of the beams consistantly. So with the existing and cellulose i should have an R value of R3 per inch so about R20-21.

Then I plan on rolling batts of R-19 (criss crossing the existing) over top the beams and current insulation. I will use batts without the backing since the original already has this. This should get me up to R39-40 range. Part of the reason why iím going with this approach is that I do have some storage space up there and also want the ability to be able to get to areas up there if needed (wiring, repairs, mouse traps etc). So i do have some plywood up there and figure i will just lay the batts over them and if i need to access it i will just move the batts out of the way. So here come the questions:

Is my plan sound?

Should i install R25 instead of the R19?

Since Iím not doing a ton of cellulose can i install/spread by hand and not use a blower? Any tips on doing this and how to spread?

If the existing insulation is blackened iíve read that you should remove and seal any gaps that air is coming through. What should I use to seal it? Expanding foam? I dont think caulk will hold up long term.

Areas where there is plywood, will adding the batts over it help insulate?

They sell rolled insulation with a platic covering to help prevent itchyness, the platic is perforated to allow airflow. Should i be concerned with it building up moisture over time?

Thanks any help, tips, advice or links to other helpful forums will be appreciated.
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Old 01-01-06, 02:53 PM
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adding additional insulation

Look at Owens Corning Miraflex. It is a white fiber insualtion encapsulated in a pink aerated membrane. It comes in a roll about 12" in diameter, but when you cut the outside packaging, run, because it starts to expand. It will loft to about 9", so you are getting at least R21. Best of all, it don't itch!!
Your plan is right on target, and the Miraflex can be installed as you would non-moisture barrier insulation.
Old 01-05-06, 04:51 PM
Join Date: Mar 2005
Posts: 64
I do not think they make this Miraflex any more. I used it in my attic and when i went to get some more i was told it is not made anymore.

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