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-   -   Really basic insulation question (http://www.diychatroom.com/f103/really-basic-insulation-question-166330/)

kellah 12-12-2012 07:28 PM

Really basic insulation question
 
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My wife and I are first time homeowners so this is my first crack at some of this, and as such need some input.

My problem: The previous owner of our house must have had some sort of a critter problem in the basement. There is poop and sunflower seed shells everywhere in the ceiling and behind the insulation between the floor joists. Most of this insulation between the joists has been chewed through, pooped on, or destroyed otherwise.

My solution: We bought some new insulation and are going to replace all of the damaged existing stuff.

I have two questions:
  1. Why is the existing insulation unfaced? Should I rip the facing off what I bought?
  2. If I keep the facing, should I staple the flanges to the floor joists or is that not necessary. The instructions on the packaging say to staple "as needed".

For a visual, I attached a photo of what I'm dealing with. I put up the faced insulation on the left. The original is on the right.

joecaption 12-12-2012 10:50 PM

Might want to look at some of the post already posted in the past few days on this exact same subject.
Also go back and add your location to your profile. Really important with a question about insulation.

Windows on Wash 12-13-2012 08:26 AM

Quote:

Originally Posted by joecaption (Post 1072162)
Might want to look at some of the post already posted in the past few days on this exact same subject.
Also go back and add your location to your profile. Really important with a question about insulation.

+1

Might as well seal it up prior to replacing the fibrous stuff.

Plenty of threads on how to seal up ribbon boards.

hammerlane 12-13-2012 09:21 AM

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If you can afford it, spray foam is the way to go. The batt insulation will not stop the air infiltration. After I had my basement rim joist cavities all done with the spary foam, not only warmer but found less insects in the basement.

kellah 12-13-2012 11:26 AM

Quote:

Originally Posted by joecaption (Post 1072162)
Might want to look at some of the post already posted in the past few days on this exact same subject.
Also go back and add your location to your profile. Really important with a question about insulation.

I added my location (Detroit, MI). I also took your advice and read around, but this has lead to more questions (see below).

Quote:

Originally Posted by Windows on Wash (Post 1072269)
+1

Might as well seal it up prior to replacing the fibrous stuff.

Plenty of threads on how to seal up ribbon boards.

I didn't know what the ribbon board was, so I had to look it up. Am I correct in understanding that is the board behind my insulation that the joists attach to?

Quote:

Originally Posted by hammerlane (Post 1072291)
If you can afford it, spray foam is the way to go. The batt insulation will not stop the air infiltration. After I had my basement rim joist cavities all done with the spary foam, not only warmer but found less insects in the basement.

We've had a horrible time with Boxelder bugs getting in this year, so that makes sprayfoam quite intriguing. I'll have to research the cost to see if that would be feasible, but I'm thinking it will be more than I want to spend. I'm assuming sealing up the ribbon board as "Windows on Wash" suggested would have that same type of effect?

---

After reading around here a bit this is what I'm thinking. Rigid foam board against exterior wall, seal those joints and cracks with a spray foam, then put my batt insulation on top of that. Found this image illustrating it from another post:

http://www.buildingscience.com/docum..._figure_02.jpg

Does that sound correct? I do have a few follow-up questions.

Sealing the ribbon boards
Caulk vs some sort of spray foam, like Great Stuff? I assume foam is the better way to go, just more expensive?

Facing or no facing?
There appear to be two schools of thought on this. I was under the impression you want to have the facing on facing the interior of the home as a vapor barrier. However, I was reading a post here that suggests the facing will not stop air movement. I could be wrong there. To leave the facing on or take it off?

Gary in WA 12-15-2012 12:13 AM

With solid wood rim boards rather than engineered rims, they do change more with the seasons; http://www.buildingscience.com/docum...d-but-strange/

How much...: pp.51; http://books.google.com/books?id=iwS...joists&f=false

I would use a good caulking that can move 1/4-3/8", with a backer rod behind it to get the optimum "hourglass shape"; pp.35;http://books.google.com/books?id=XHA...0break&f=false
May be difficult to get a perfect air barrier this way...

Or, less time, canned foam, though closed cell does shrink more over time letting air behind it, than open-cell foam. I think "Great Stuff" is c.c., check on the other type... Take off the facing, needs to dry to the inside only with all that thick f.b.
OTOH, read the second section (end of link) on exterior permanence with class of vapor barrier or retarder required; http://www.buildingscience.com/docum...vapor-barriers

Gary

kellah 02-22-2013 12:02 PM

Follow-up question regarding brick cavity
 
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I'm finishing up some of the insulation in my basement based off of the recommendations provided on here. I've now run into another scenario I'm not sure how to tackle.

There is a section of basement wall where the ribbon board extends out to the exterior brick wall and leaves a ~3" gap exposing the cavity between the brick and interior wall. See the attached photo for reference.

We have a lot of insects getting into the basement and I'd like to close this gap to help with that problem in addition to the cold air movement. My first thought was to somehow close that gap with foam board and then stick my batt insulation over it. However I am then concerned about trapping moisture back there with no where to escape. As far as I can tell there is nothing in place to allow the cavity behind the brick to breath.

What are thoughts on how I should tackle this?

My apologies if I'm missing important facts, I can provide more info if I missed something.

drtbk4ever 02-22-2013 12:09 PM

Really good question kellah. I'm too am curious as to the answer from the experts.

Gary in WA 02-22-2013 10:16 PM

Exterior picture of the problem area would help...

Gary

kellah 02-23-2013 05:50 AM

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Quote:

Originally Posted by Gary in WA (Post 1122802)
Exterior picture of the problem area would help...

Gary

Here you are. The section of wall in question is below a deck and partially below grade.

Gary in WA 02-23-2013 08:08 PM

I'm having trouble seeing if the board is a floor joist extension cantilevered out to the brick veneer or just installed directly to the veneer. The rim should have f.b. on it as wood R-1.5 per inch thickness. The veneer cavity should be top-vented to the outside and weep holes below to the outside. No air exchange to the rim joist cavity, seal with plywood, fibrous insulation or best yet; http://www.buildingscience.com/docum...n-crawlspaces/ That would entail cut-n-cobble f.b. between the joists.

Gary


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