Blow In Insulation

[Brad Wood]

Anyone do this to their house?

I'm trying to figure out how much of the material I would need to do the attic above my garage (which is also my shop).
I realize there is a whole "r value" consideration, but since I don't have anything at all, I figure 6 to 8 inches ought to make a pretty big difference in my garages ability to retain heat (the walls are already insulated with fiberglass bat).

Based on my garage being 25'x25', I figured 25x25x.66, which is just under 415 cubic feet (25' x 25' x 8")... but I don't think this is correct since 25' x 25' would be 625 sq ft (sorry, math is NOT by strength)

Problem is I am looking at the material listed on the Home Depot web site and it is listed as "40 sq ft". It is pretty cheap and if I buy enough, HD rents the blower for free, so I figure I will go through them.

Anyone have some suggestions on how many of these bales I will need for my space?

Thanks

- Brad

[David G Baker]

My math isn't so hot either so I cant help you with the number of bags. You may need a moisture barrier under the insulation. The blow-in-insulation is not too expensive so when I did my pole barn I put 14 inches worth in the attic. It really made a difference in the heat loss. In my opinion you can't put too much insulation in your attic. Get yourself a good mask if you are going to do the work yourself cause it is very dirty work.

[Gene Howe]

Your figures are correct. 625 sq. ft., 8" deep would be 412 CF.
But, HD doesn't give you enough info. to calculate the # of bags.
40 sq ft at what depth? Somewhere on that bag should be a listed CU amount.

[Brad Wood]

Your figures are correct. 625 sq. ft., 8" deep would be 412 CF.
But, HD doesn't give you enough info. to calculate the # of bags.
40 sq ft at what depth? Somewhere on that bag should be a listed CU amount.

I guess I'll have to suck it up and go in... They have some weird numbers on the "specifications" page online, but it doesn't really tell you what you need.

Probably part of their evil plot to get you to walk into the store

[David G Baker]

Brad,
You can always do an approximation then add a few extra bales of insulation that you can return if you don't need it. I purchased three extra bales and ended up needing one of them and the other two are on two sides of my 2 foot by 4 foot attic access.

[Jim Becker]

Don't forget you need to install baffles at the eves to prevent the material from touching the roof deck and blocking any ventilation. And it may not be cheaper to do it yourself these days...contractors are looking for work and they can buy the material for far lower cost than you can. Even if it's a few more bucks, getting someone else to do it is not a horrible idea. (I spent a few years in the business and it's NOT fun work...)

[David G Baker]

Amen on what Jim wrote!!!!!!

[Joe Chritz]

Blow it in as deep as you can, I would go well over 8" just because it is really easy to do it when you are up there and much harder after you have several inches down. The material will compact some after it sits for a while.

25x25 is in fact 625 sq. ft. That 1 foot thick would be 625 Cubic feet. I would shoot for 12" minimum which would be 625 cu ft. Cellulose is about R 3.7 per inch although R factors are misleading a bit.

Joe

[Derek Tuchscherer]

Hey Brad I was in this same position at the beginning of winter, my garage is 18' x 24' and I had figured the material to blow in to R-30 would cost about $250, and was all set to do it myself until I called a insulation contractor, the price he quoted me was $300 for the insulation... installed. I gave him the job, he showed up on a Friday morning at 10:00 and had it blown in and was gone by 12:00. Watching him all garbed up crawling around up there made me realize how bad a mood I would have been in if I had tried to do it myself. Even if the blower rental would have been free.

Derek

[Dave Verstraete]

Brad
There are two things that you always sub out...insulation, drywall finishing and sewer pipe work...OK maybe three!

[Paul Demetropoulos]

I guess I'll have to suck it up and go in... They have some weird numbers on the "specifications" page online, but it doesn't really tell you what you need. Probably part of their evil plot to get you to walk into the store

Here you go Brad, I'll save you a trip to the evil empire

Owens Corning PROPINK Complete™ Blown-in Wall System is designed for all enclosed cavities— including walls and ceilings. R-value: 2x4 construction up to R-15, 2x6 construction up to R-23, 2x8 construction up to R-31, 2x10 construction up to R-39, 2x12 construction up to R-47.

[Ken Fitzgerald]

Brad...check with several insulation companies. I insulated the walls of my shop with R-19 fiberglass batts. I installed the insulation dams/barriers before I put the sheetrock on the ceiling while it was still easy to get to the area. It turned out to be cheaper to have it installed than I could do it with materials and blower from HD. Two young men did it in about 1 hour and they cleaned up their mess and were gone. This fat old man couldn't have begun to do it that fast. R-30 in my ceiling.

[Steve Clardy]

Mine was 40 bags I think [crs] in 2500sq.ft.

12" deep on average.

[Gene Howe]

Brad
There are two things that you always sub out...insulation, drywall finishing and sewer pipe work...OK maybe three!

+1 Experience is a great teacher.

[Paul Atkins]

I had my house blown 20 years ago and I'll have to say I'm glad I didn't do it myself. As they were doing it I could hear and feel the difference. Last year we decided to redo the kitchen by raising the ceiling which meant removing 350 sq. ft. (8"deep). What a mess to deal with. In that case, bats would have been better. If there is an area that might be altered you might think of that.