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flash and batt bulging - will this be a problem for drywall?

flash and batt bulging - will this be a problem for drywall?

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  #1  
Old 12-05-14, 04:39 AM
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flash and batt bulging - will this be a problem for drywall?

Hi All,

I'm finishing my basement and have the following situation. 2x4 framing set back about 1" from the poured concrete walls. I had 1.5" of closed cell foam sprayed and am currently topping that off with R-15 Roxul. Spray foam appears to have been done well, but of course is uneven in places. This causes the Roxul to bulge out up to about 1" but generally 1/4 to 3/4".

I understand it is not ideal to compress the insulation, but will the drywallers be able to do it without having screws pop all over the place? Perhaps using 5/8 drywall? Or am I going to have to add furring strips over the studs to provide a little more space? Roxul is not as compressible as fiberglass so I fear my strategy may have just led to more work (i.e., furring strips).

Thanks!
 
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  #2  
Old 12-05-14, 05:01 AM
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You are correct that the Roxul does not compress as well. But the Roxul does cut very easily. You might try a hand saw layed flat across the studs and work it down shaving off the excess. When they blow in wet cellulose they have a machine that does this job.

And, no, don't leave it for the drywallers, they won't want to waste time fussing with it.

No vapor barrier and hopefully your foam layer will allow some drying to the inside.

Bud
 
  #3  
Old 12-05-14, 05:29 AM
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Thanks! I tried that in a couple stud bays and it's messy but does the job. Might try just cutting off 3/4 of an inch before placing the rest of the batts.

Was planning no vapor barrier. Hard to find consensus on anything online but that seems to be one thing everyone agrees on.
 
  #4  
Old 12-05-14, 06:35 AM
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Join Date: Oct 2008
Location: New England
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I was just cutting some for insulating around some new windows and I used a long fine toothed bread knife and it cut perfectly, no mess.

Since you want the insulation to fit well against the flash, look for any areas where a little trimming of the foam will help.

Let me get innovative for a moment. The handles on most hand saws can be removed and there is frequently another hole at the tip. Once the handle is removed consider a 2x piece of wood spaced out at each end with the saw blade mounted flat. The finer the blade on the saw the better.

If you trim each one as they are installed the saw configuration won't bump into the next stud bay.

Just a thought, and a little compression is not bad.

Bud
 
  #5  
Old 12-05-14, 06:53 AM
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Yes. Just did a quick test on my way out the door with my hand saw but I think the teeth are too coarse. When I cut previously with the bread knife (finer teeth) it was pretty smooth. I'll probably pull out what I've done (only a couple short walls) and trim as you suggest as I install them.
 
  #6  
Old 12-05-14, 07:19 AM
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An electric carving knife would likely be even easier, if you have one.
 
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