Need basic help for attic re-insulation (with pics)


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Old 05-17-09, 01:36 PM
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Need basic help for attic re-insulation (with pics)

Hey All,

Im hoping for some help and confirmation on my insulation project. Here is the scoop

New York, 1950 Cape Cod. I have major cold air leaks into the house ( as you will soon see ).

Here is a picture of the attic space at the back of the house. Where there is insulation on the floor, its ancient and mostly useless. Its so old, I was just going to rip it all out and replace with 15" R30. The rafters on the right, facing roof/outside, dont need to be insulated, right?





The wall which faces the upstairs bedrooms ( on the left) has insulation, definitely old, but possibly salvagable? I can just fix where it has come loose? Should I replace it? There are some electrical wires going across and it will be tricky, but it should be done, right?




And here is the final issue/question. There is an opening for the waste pipe for the house from the attic all the way down to the basement which is filtering cold air right down to the kitchen on the first floor. I need to insulate this to prevent cold air from working its way down into the house. What is the best way of doing this? Just pack fiberglass around it in the attic?



Thanks for your help!
 
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Old 05-17-09, 03:31 PM
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Hi Bones, Ok you are at the right point to be asking and you have the opportunity to make some real improvement.

1. In cold country, your vapor barrier needs to be on the inside (warm side) of the insulation. What I see has it on the cold side. If you re-install kraft faced insulation, simply slice the kraft every 6 to 12 inches. A 10 inch slice across the kraft leaves enough to hold it in place.

2. I can't see for sure if there is a block under that knee wall to prevent air from circulating under the floor of the adjacent room. Needs to be one.

3. The insulation is in bad shape, but some people prefer to simply cover it rather than disturb all of that dust and old fiberglass. Fill the space, excuse me, I'm sneezing just thinking about the dust anyway, fill the space between the joists up to level and then run across with another layer.

4. So, for the large thermal bypass, cover it with metal flashing or sheetrock as a fire block, then fire rated can foam to seal all of the gaps and cover with insulation. No need to fill the space around the pipe unless it has access to an outside wall.

5. I'm a bit concerned about the copper pipe I think I see next to the vent pipe. After you super insulate this space, it will get cold and a simple layer of foam insulation will not keep it from freezing. Where does that pipe go and are there others. Is this space vented at the soffit and up to the gables or ridge?

There are additional suggestions, but need to know about those pipes.

Also, here is a link about capes:Welcome To Home Energy Magazine Online

Later,
Bud
 

Last edited by Bud9051; 05-17-09 at 03:35 PM. Reason: spelling
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Old 05-17-09, 03:46 PM
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Hi, and welcome. Bud beat me to it, again. Well, I can give you my other reference:

http://www.buildingscienceseminars.c...2-12-Roofs.pdf

Either page 4 or 6, now I'm not sure, is a picture of your cast iron main drain/vent pipe, and how to air seal it. Be safe, G
 
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Old 05-17-09, 03:58 PM
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1. In cold country, your vapor barrier needs to be on the inside (warm side) of the insulation. What I see has it on the cold side. If you re-install kraft faced insulation, simply slice the kraft every 6 to 12 inches. A 10 inch slice across the kraft leaves enough to hold it in place.

You mean the insulation on the kneewall, correct? Yes.. I noticed that too. That insulation would need to be pulled and then reinstalled with the paper on the inside. Then I wouldnt need to slice anything?



2. I can't see for sure if there is a block under that knee wall to prevent air from circulating under the floor of the adjacent room. Needs to be one.

I do believe that there is a space under there for air flow--but Ill verify. I think there is space above as well.



3. The insulation is in bad shape, but some people prefer to simply cover it rather than disturb all of that dust and old fiberglass. Fill the space, excuse me, I'm sneezing just thinking about the dust anyway, fill the space between the joists up to level and then run across with another layer.

Good call about the dust. Since Ill be leaving it there and adding to it would I use batts without a vapor barrier? Or would I get batts with a vapor barrier since the old stuff is just that pathetic??



4. So, for the large thermal bypass, cover it with metal flashing or sheetrock as a fire block, then fire rated can foam to seal all of the gaps and cover with insulation. No need to fill the space around the pipe unless it has access to an outside wall.

So, if Im reading this correctly, just cut some drywall to cover up the space and hole to create a "floor" and just insulate the crap out of it? Or did you mean to wrap the pipe with something?



5. I'm a bit concerned about the copper pipe I think I see next to the vent pipe. After you super insulate this space, it will get cold and a simple layer of foam insulation will not keep it from freezing. Where does that pipe go and are there others. Is this space vented at the soffit and up to the gables or ridge?


The copper pipe--is a feed and return of hot water to the baseboards for heat in one of the upstairs rooms---coincidently-- there is no heat in that room--no water goes through the pipes (that is my next job!). There is an old school radiator in the other upstairs room which DOES work.

And I believe that it is vented at the soffit. Should I get those things which go in between rafters to allow for air to get in?
 
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Old 05-17-09, 05:55 PM
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[QUOTE=Bud9051;1569944]Hi Bones, Ok you are at the right point to be asking and you have the opportunity to make some real improvement.

1. In cold country, your vapor barrier needs to be on the inside (warm side) of the insulation. What I see has it on the cold side. If you re-install kraft faced insulation, simply slice the kraft every 6 to 12 inches. A 10 inch slice across the kraft leaves enough to hold it in place.

I don't see a VB on the cold side! Where is it?
 
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Old 05-20-09, 06:58 AM
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the paper on insulation I believe acts as a vapor barrier, but it should be against the heated side. It is currently on the cold side of the attic walls. I think I would need to pull it out, turn it around and reinstall is with the paper facing the other side.
 
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Old 05-20-09, 03:29 PM
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Nope paper is not a VB! Not enough perm rating to be a VB.
 
 

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