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Discussion Starter #1
Hello all,

I am about to start a project in Philadelphia that includes a new kitchen. The current walls are plaster and the homeowner would like this torn down and drywall to be put up. The walls are brick and we need to insulate the walls we build before we install drywall. I would like to keep it a 2x4 wall but with r13 we still need some more insulation. Is it up to code if we put 1" foam board directly on the brick and then a 1" air space with a 2x4 wall and r13 batt insulation. Thank you in advance!
 

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Build your new wall (2x6 if possible) get all electrical/plumbing in and call in a spray foam insulation company and be done with it. You're not going to get better than that.
 

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Discussion Starter #4
Home owners are trying to keep costs low so spray foam isn't an option...i wish it was though. My concern is, will putting up 1" foam on brick going to cause moisture problems? or any other problems? I'm wondering if this is a normal insulating practice. I'm used to working in new homes, only doing trim but now I'm working with a company that does renovations, so this is a little new to me. Thanks
 

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wannabe
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In the past, we have stapled house wrap to the back of our walls before standing them in basements. Also, you can get "dense pack" insulation @R-15... Brick, airspace, r-15, DW, .... where I am r-21 is code so you might be getting close adding up the R-value.....
 

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Sean
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The answer to foaming brick is - it depends & that would be by spraying a closed cell foam on it - not using foam board

Building Science Corp had a great piece on this subject a while back & ways of testing it.

As for basements, generally you are applying something like Delta Dry, running it long to a French drain & then attaching foam board to it as you are not worrying about the bricks spalling, etc...
 

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Renaissance Man
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I wouldn't have a problem using Dow foamular right up on the brick - this is solid masonry he is talking about - not veneer work. You typically don't see weeps in older homes in Philly, but rather find through wall flashings buried above openings and under sills.

According to foamular rep conversation one day,...they don't consider it a vapor barrier unless it runs 2" thick. Not sure how others feel on this.

Since this isn't truly new construction and your dealing existing conditions - the inspector may let you slide with less insulation if it effects existing door openings and such when tolerances are tight.
 

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Discussion Starter #11
thank you superseal, i will have to check with inspectors on what they will allow. I should have been more specific in my original post as to the type of brick work it is. It is double wythe brick walls. Walls are shared with neighbors on both sides.
 

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Eater of sins.
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thank you superseal, i will have to check with inspectors on what they will allow. I should have been more specific in my original post as to the type of brick work it is. It is double wythe brick walls. Walls are shared with neighbors on both sides.

Wait, if the other side of the wall is heated interior space then what is the worry about a vapor barrier?

Andy.
 

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Sean
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is there any advantage to using foamboard against the brick and then an airspace as per the original post Sean?
Thanks, I missed that part & in short - no, not really - while it may help prevent some heat from entering the house, it's doing nothing to prevent heat from leaving.
Now as for it being a common wall, there might be an issue with flammability, and the need for it diminishes as we are not dealing with the temp differences between inside & outside, but rather between two units which should be a heck of a lot smaller. 60 degrees vs 5?
 

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1" foam has a 5 r value add the 13 and your at 18,add another layer of 1" foam and thats 21. Alayer of soundboaed would help with noise also
 
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