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Build & Remodel

Air leak add on room

Back in early '90s my parents converted the back porch into a another room. The contractor kept the actually brick up that was on the back of the house and just built 3 walls to enclose it. I can now see a opening between the original brick and the wall he built. I can see the outside If line my eye straight down the brick line. Can I just get some sealant or something to seal it up? I know it is eating up the electricity bill.
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Posted 2015-10-22T19:20:57+0000  by jplaya517 jplaya517
Hi jplaya517,

Great Stuff is expansion foam that is commonly used to fill voids in construction material.

You might start by applying this into the seam and then use GE Silicone II caulk to prevent moisture from leaking into the void.

Expansion foam should not be over applied ... it can expand outside your working area and make an unsightly mess.

If this happens, be prepared to strip off the excess before it dries.

A trowel, putty knife, mineral spirits and several rags will be handy when working with this product.
Posted 2015-10-22T19:42:15+0000  by Pat_HD_ATL

Hello jplaya517.  

Great Stuff sealant is an excellent product but it cannot be exposed to the suns UV rays, so you must paint it. If you use it in a deep cavity, you still need to apply a top covering of caulk as Pat mentioned.

My suggestion would be to use a backer rod (see picture below) push it into the crack about 1/2 to 3/4" below the surface, then apply an exterior sealant such as Sikaflex Construction Sealant. It is a single component polyurethane used to seal joints and gaps in walls, floors, balconies, around window and door frames and other building gaps. Highly elastic, this sealant cures to a tough and flexible consistency with excellent cut and tear resistance. It is paintable, stainable and sandable and provides an excellent weatherproof seal. The sealant will fill gaps between brick, block, masonry, wood and concrete or even metal frames. 

Posted 2015-10-22T20:11:57+0000  by Angelo_HD_CHI
While you can certainly seal the gap something else you should consider is why the gap is developing in the first place.  I might suspect that the structure is starting to pull away from the main house and that will likely continue in the future leading to more problems.  Typically porches don't have the same type of foundation system as a house because they don't need to support that kind of load.  That's not to say your room will suddenly collapse but rather just something you should think about and perhaps get a qualified person in to take a look at things.
Posted 2015-10-23T10:23:47+0000  by Adam444
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