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Old 10-01-2009, 08:30 PM   #1
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My own insulation questions, what to buy?


I have been in this house about 15 years and have always thought the insulation was probably inadequate. I have bee reading some of the threads here and also found links such as http://www.ornl.gov/sci/roofs+walls/...on/ins_06.html which I found very helpful.

I live near Chicago and learned that my R value in my attic should be R38. I have R19 paper side down. According to what I've read I can put a second layer of R19 and then I will have R38. But what about the fact that the original layer is 27 years old? Won't it lose "R" value over time?

My wife wants me to rip it all out and completely replace it. I see that as a waste of time and a huge mess. What should I do here?

Another question is that insulation seems to be on sale right now. What should I buy? There are multiple brands and types. We were at one store that had R38 cheaper than some of the R19, I don't get it.

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Old 10-01-2009, 08:51 PM   #2
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My own insulation questions, what to buy?


I'd add additional unfaced insulation on top of and perpendicular to what you have. No need to tear out existing. I can't figure out the pricing schemes, but obviously go wit the cheapest cost per square foot per R-value

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Old 10-01-2009, 08:57 PM   #3
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My own insulation questions, what to buy?


I agree with previous post, absolutely no need to remove existing insulation unless it is wet, in which case you have much bigger problems. Assuming it is dry, you can simply add Owens Corning or equivalent fiberglass batts on top, as noted. The reason you want unfaced batts is because you already have a moisture retarder in place, and you would not want to trap any moisture between two moisture barriers.
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Old 10-02-2009, 12:48 PM   #4
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My own insulation questions, what to buy?


What about the R value? Does that deteriorate over time?
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Old 10-02-2009, 12:49 PM   #5
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My own insulation questions, what to buy?


RValue as far as I know does not degrade over time
If it is compressed - pressed down...then RValue is reduced
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Old 10-02-2009, 02:08 PM   #6
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My own insulation questions, what to buy?


Check on the pricing.

Perhaps a bundle of R38 is cheaper than a bundle of R19, but it will cover less square footage.
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Old 11-13-2009, 11:03 PM   #7
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My own insulation questions, what to buy?


Do I need to add vents? They sell plastic vents that insert into the soffets. My roof has cardboard in there but I don't even know what they are for.
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Old 11-13-2009, 11:10 PM   #8
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My own insulation questions, what to buy?


You mean the rafter vents to the soffits like these?
I use the plastic ones, they sell styrofoam ones too
I've seen pics of the cardboard vents, but never in a store
I make sure they go down to the soffits
I install blocking at the outside wall between the rafters
So that's as far as my insulation goes


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Old 11-14-2009, 12:42 AM   #9
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My own insulation questions, what to buy?


Here is the best way to insulate over the outside wall, if you have the room, seal the air leaks from any holes there first (electrical, plumbing, etc.): http://www.southface.org/web/resourc...lings_4pdf.pdf
Page #2, across from cathedral ceilings. A block on edge of rigid board (R-41) has way more R-value than a solid wood board, 2x6 (R-7).Here is the way to seal a very shallow roof slope: http://www.homeenergy.org/archive/he...96/961110.html
If cardboard baffles, they could easily get wet from moist air passing over them and molding. I would replace them with foam ones.
Do you have soffit and ridge vents?

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Old 11-14-2009, 01:08 AM   #10
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My own insulation questions, what to buy?


They look fine. We replaced the roof in 1999 and my roofer buddy was amazed that there was no paper under the shingles except the peaks and valley's and there was very little moisture damage. There are no vents in the soffets at all.

What do those "baffles" do?

I'm still debating as to whether I should add more or replace the old. The Old is from 1982 and seems OK but matted in some spots. Mice were up there too and made tunnels in it.

Last edited by Hurriken; 11-14-2009 at 01:13 AM.
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Old 11-14-2009, 08:49 AM   #11
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My own insulation questions, what to buy?


Quote:
Originally Posted by Hurriken View Post

Mice were up there too and made tunnels in it.


That's the reason your wife wants it all replaced I bet.

I can see her point. Who wants mouse "stuff" in the ceiling? Can you tell if the mice got into all of it, or was their activity localized to one part? Maybe there's a compromise position in tearing out the parts with the most of the damage and leaving the rest.

Fiberglass gets it's R-value from the air that the glass fibers hold. Glass doesn't deteriorate over time. If the air cavities are filled with dirt the insulation looses it's value, or if the insulation is squashed and the air cavities go away the same thing. If it's kept clean and dry it should keep it's R-value forever.

Other than the mice aspect, I'd definitely not remove the old. You can just pile R-38 on top of what you have and get more R value than if you tear it out and put in R-38. Why waste what's up there, even if it's somewhat diminished in R-value. Except for the mice, that is
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Old 11-14-2009, 11:58 AM   #12
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My own insulation questions, what to buy?


I have removed all sheetrock above my fireplace do to a leak. the leak has been repaired and I need to know if I can insulate the walls before installing new drywall? There was none there before.
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Old 11-14-2009, 12:40 PM   #13
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My own insulation questions, what to buy?


"There are no vents in the soffets at all."

The baffles are intended to ensure air flows freely from the soffit vents, up through the attic and out the ridge or roof vents. If you have carboard baffles in your attic, hopefully you do have venting at the soffits and just don't see it. Without the baffles, insulation gets pushed up against the roof, and blocks the airflow. Your attic needs ventillation. If your buddy was a pro roofer, he should have looked to see the attic was properly ventilated.
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Old 11-14-2009, 10:08 PM   #14
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My own insulation questions, what to buy?


Quote:
Originally Posted by pyper View Post
That's the reason your wife wants it all replaced I bet.

I can see her point. Who wants mouse "stuff" in the ceiling? Can you tell if the mice got into all of it, or was their activity localized to one part? Maybe there's a compromise position in tearing out the parts with the most of the damage and leaving the rest.

Fiberglass gets it's R-value from the air that the glass fibers hold. Glass doesn't deteriorate over time. If the air cavities are filled with dirt the insulation looses it's value, or if the insulation is squashed and the air cavities go away the same thing. If it's kept clean and dry it should keep it's R-value forever.

Other than the mice aspect, I'd definitely not remove the old. You can just pile R-38 on top of what you have and get more R value than if you tear it out and put in R-38. Why waste what's up there, even if it's somewhat diminished in R-value. Except for the mice, that is
While she is grossed out by mice...it's a fairly regular battle I wage because we back up to a wetlands preservation...she is really thinking that the old insulation must be bad because it is old. My thought is that tearing it out would be a huge mess and a problem to dispose of.

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SPS-1 "There are no vents in the soffets at all."

The baffles are intended to ensure air flows freely from the soffit vents, up through the attic and out the ridge or roof vents. If you have carboard baffles in your attic, hopefully you do have venting at the soffits and just don't see it. Without the baffles, insulation gets pushed up against the roof, and blocks the airflow. Your attic needs ventillation. If your buddy was a pro roofer, he should have looked to see the attic was properly ventilated.

He said it was good but that was ten years ago. I don't know enough to know except, by soffit vents I was thinking about the little circle plug vents you can install. Is it possible that it vents through the corrugated(for lack of a better description) siding? I'll have to take a picture of it. When we did the roof he added three more vents to the top of the roof.
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Old 11-17-2009, 12:45 PM   #15
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My own insulation questions, what to buy?


Here are my soffits. Does "notched part serve as vents?


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