# How to fill gap in exterior between house & foundation



## Bolkswagen (Apr 29, 2017)

I apologize if I am using the incorrect terminology. I have owned a home for 1.5 years and know very little about this type of thing. 

From what I've read so far, I think it's the sill plate gap? Anyway, my house was built in 1945, initially a basement house, then they build up. It's a concrete block foundation. I'm unsure if you need anymore information, but let me know. 

I think the previous owners had water issues in the basement, but I haven't seen any, although it smells musty down there (there are no opening windows). There is about a 3/4" gap (max, some areas less) that I'd like to fill, but am unsure with what. I saw some forums say use spray foam, caulk (silicone based, or?), foam backer + caulk, grout, not grout. I'm just kind of confused. I'd like to know what I should use, what products you recommend, any tips, etc. 

Note: there's only really a gap on the front and back of the house, the sides are fine (maybe not totally sealed, but close).

It appears someone tried to fix it with concrete (maybe, see picture), but that part is falling off now.


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## Windows on Wash (Aug 30, 2011)

I would look at some backer rod and a proper masonry sealant. You want to treat this a bit like an expansion joint.

Would a piece of flashing work here from an aesthetic standpoint?


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## Bolkswagen (Apr 29, 2017)

Thank you for your response! what type of masonry sealant should I use (could you give me an example?)? Yesterday, I tried a tube of Akona Concrete Repair, but didn't get far without the backer, as the depth is deeper than I thought, and it's quite wide.

What kind of flashing would you recommend? It looks like a good idea, but am unsure how to install. Does that go on after the backer and sealant? 

I apologize for all of the questions, as I said, I'm very new to this.


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