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Old 10-06-2008, 05:42 AM   #1
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Insulating attic floor AND rafters?


I have some questions about how to proceed based on the specifics of my situation.
I live in the northeast where it can be very cold in the winter and sometimes very hot in the summer.
My 55 year old house has some very old yellow fiberglass insulation in the rafters of the attic.

It was installed backwards, with the vapor barrier facing up, instead of down and some of these batts have foil that is crumbling when you handle it.

My goal is to maximize the insulation.

Since I need to handle this old stuff anyway, in order to put it facing the right direction, I had the thought that I might put it above in the roof rafters and then get some new insulation to put between the floor joists.

I do realize that this is not the proper place to put insulation and that it won't do much to help insulate the house.
However, the alternative is even less appealing - hauling it all down through the house and out to the dumpster.

My question is while it might not do much good in the roof, would it do any harm? If I'm thinking of it as waste anyway, rather than go through the hassle of throwing it out, if I placed it in the roof, it would just serve to keep my attic from getting quite as hot, which in turn could help the rooms below to some degree.

As I see it, I have 3 choices:

1. Pull it up and throw it away in order to make room for the new stuff.
2. Leave it where it is (after reversing the barrier side) and put another layer of new stuff perpendicular over it.
3. Pull it out and place it in the rafters above, while putting some new stuff in its place between the floor joists.

Any suggestions would be much appreciated

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Old 10-06-2008, 06:20 AM   #2
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Insulating attic floor AND rafters?


personally, i'd just leave it and use blown cellulose over it.

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Old 10-08-2008, 06:34 AM   #3
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Insulating attic floor AND rafters?


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personally, i'd just leave it and use blown cellulose over it.

DM
Thanks.
Due to the fact that I already have several rolls of R30 batts and that I prefer the ease of just picking up a batt and moving it out of the way when doing any wiring, etc. from the attic, I'm going to stick with 2 layers of batts, one perpendicular over the other.

However, I'm still stuck on whether or not to move the old stuff or just leave it be. My primary concern is not convenience, but whatever is going to give me the most comprehensive insulation job.
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Old 10-08-2008, 07:06 AM   #4
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Insulating attic floor AND rafters?


gotcha. well, i'd think you'd want to keep warm as much as possible, so i'd go with option #2. didn't know the details. just an fyi, all the wiring i'm running through my new addition is 2' above ceiling level on wood strips, neatly stapled and tied. still seen, safe, and accessible after blown cellulose is added. i also label each wire with a sharpie as to what it is. even the outlets, line in, load out. elec. inspector liked that. =o)
but yeah, i'd go option 2, the crumbling foil shouldn't matter. have a great day!

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Old 10-08-2008, 11:10 AM   #5
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Insulating attic floor AND rafters?


Step 1. Staple a radiant heat barrier to the underside of the roof. This reduces the heat in the summer. Radiant heat goes right through insulation.

Step 2. Caulk or spray foam all plumbing and electrical penetrations into the attic. There are many of them. Insulating does not do much good if outside air flows freely into the house.

Step 3. Blow cellulose over the existing insulation. Make it thick.

You'll save lots of money. The cost of materials is low. If you pay someone to do these things, your payback period will be very long.
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Old 10-09-2008, 10:49 AM   #6
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Insulating attic floor AND rafters?


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Step 1. Staple a radiant heat barrier to the underside of the roof. This reduces the heat in the summer. Radiant heat goes right through insulation.

Step 2. Caulk or spray foam all plumbing and electrical penetrations into the attic. There are many of them. Insulating does not do much good if outside air flows freely into the house.

Step 3. Blow cellulose over the existing insulation. Make it thick.

You'll save lots of money. The cost of materials is low. If you pay someone to do these things, your payback period will be very long.
This is my existing plan and seemingly the preferred energy saving method. Maybe the OP can take back his batts?
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Old 10-09-2008, 04:44 PM   #7
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Insulating attic floor AND rafters?


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Originally Posted by John FX View Post
Thanks.
Due to the fact that I already have several rolls of R30 batts and that I prefer the ease of just picking up a batt and moving it out of the way when doing any wiring, etc. from the attic, I'm going to stick with 2 layers of batts, one perpendicular over the other.
he wants to use batt to be able to move it if needed.

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Old 10-10-2008, 06:51 AM   #8
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Insulating attic floor AND rafters?


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Originally Posted by MdangermouseM View Post
he wants to use batt to be able to move it if needed.

DM
I'd like to.
This idea came from a friend of mine who has blown in and he says it's horrible to deal with if you ever have to do anything in the attic, such as wiring.
He says it's all dirty and dusty - granted his is old, but mine will be some day, too if I put it in now.
He also said it's difficult to move because it's loose and you can't quickly or easily move it aside if you're trying to get to something without creating a big dust storm.

What do you think?
I'd be curious to hear the opinions of others who have had blown in for awhile.
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Old 10-10-2008, 07:25 AM   #9
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Insulating attic floor AND rafters?


IMHO blown is the superior choice. but you are right, it is a dust storm if you have to do anything up there. be sure to wear a mask if you decide to use it and do it yourself. but if you did blown, had a problem, and moved it SLOWly, the dust raised would be minimal. the problem i had at the old home with the blown was not seeing where boards were to step on. ( i had to replace knob/tube) perhaps if you do any wiring repairs/upgrades BEFORE you add cellulose or batt? =o)
however you decide to tackle this, best to hustle up... winter's a comin'! *brrrr*

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Old 10-10-2008, 10:43 AM   #10
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Insulating attic floor AND rafters?


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Originally Posted by MdangermouseM View Post
IMHO blown is the superior choice. but you are right, it is a dust storm if you have to do anything up there. be sure to wear a mask if you decide to use it and do it yourself. but if you did blown, had a problem, and moved it SLOWly, the dust raised would be minimal. the problem i had at the old home with the blown was not seeing where boards were to step on. ( i had to replace knob/tube) perhaps if you do any wiring repairs/upgrades BEFORE you add cellulose or batt? =o)
however you decide to tackle this, best to hustle up... winter's a comin'! *brrrr*

DM
Not to beat a dead horse here, but just to hopefully gain from your experience, could you tell me, aside from the dust, if blown in is just a pain to move?

Here's what I'm envisioning - I need to do some electrical or cable work up there and have several bays and/or several yards of distance in which I need to pull all this loose stuff aside and empty out the space between each rafter to do something.
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Old 10-10-2008, 02:18 PM   #11
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Insulating attic floor AND rafters?


it's easy enough to move around if needed, just do it slowly. and be sure to replace when done. and it won't make your arms all itchy like fiberglass. most here will agree that cellulose will be superior R-value than perpendicular. batt, i'm sure.

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Old 10-10-2008, 10:50 PM   #12
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Insulating attic floor AND rafters?


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Originally Posted by MdangermouseM View Post
it's easy enough to move around if needed, just do it slowly. and be sure to replace when done. and it won't make your arms all itchy like fiberglass. most here will agree that cellulose will be superior R-value than perpendicular. batt, i'm sure.

DM
I would agree with this.

An alternative to this is blown fiberglass but it's physical and insulative properties are not that of cellulose. But it's not dusty. It's clean & fluffy white!

I also agree that if you have any work to be done in the attic, get it done now before the insulation job. On a side note, how difficult is it going to be if you had to run some wire/cable the whole length of your house when you've got FG batts all over running perpendicular to each other? That sounds like battle to me. Just me 2 cents worth.

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