# Spray Foam between Siding and Foundation?



## Peter D.

I'm having a big problem with mice. Specifically, mice getting into the attached garage, leaving droppings everywhere, freaking me out when I empty the trash, nesting in my car engine, lying dead on the floor when I drive away, etc.

My plan is to shove some copper mesh between the exterior foundation wall and the siding. I've read on the internets that that it's a good idea to spray some foam behind the mesh to keep it in place and prevent the mice from pulling it out with their teeth.

My question is about the potential for moisture problems. Is this gap between the concrete and the siding important? There's a combination of cedar shingles, and vertical cedar siding. The house is 50 years old and there's probably not much of a moisture barrier. 

Would I be making a bad situation worse by spraying foam in there or is it okay? I live in CT and it can get really humid in the summer. The house sits on a slab. There's no crawl space or below ground basement.

Thanks!


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## Tom Struble

yes...it's important to have space between concrete and wood

are you sure the mice are not getting in around the bottoms of any doors?

any pictures?


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## Peter D.

Thanks for the quick reply.

It's too dark to take pictures right now. But I can tell you all the doors are sealed off and I have new garage doors which make tight contact to the slab.

But there is kind of an odd space between the original part of the house and the addition. The electric meter was covered by the addition and is accessed through a door into a tiny cubby hole. This cubby has a big gap into the attic and there are holes into the interior walls of the garage. So today I squeezed in, ruined my sweater, and sealed all the holes with 1/4 inch chicken wire. Maybe that will fix these darned mice! Damn you, mice!!!

Back to my original question... is there a better way to seal the copper mess between the house and foundation? Maybe I can tack it in somehow without blocking air flow. Bent nails or half a staple into the siding and half into the mesh?


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## Tom Struble

as long as the bottom of any wood stays elevated and open so it can dry out you should be ok


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## AGWhitehouse

have you tried traps? Poison? Borrowing a friends cat? Getting your own cat?


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## Peter D.

Of course! We have an elderly indoor cat with no canine teeth. I think his scent keeps the mice out of the living area. And an exterminator comes every three months too. I'm just looking for a more permanent solution. We don't let the cat into the garage because he could get loose or hit by our cars.


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## joecaption

Post a picture of the area in question.


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## Peter D.

Will do! Thanks.


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## Peter D.

Rear wall









Closer, the corner where I think they enter









Underneath (and upside-down, sorry)










Mouse droppings inside the garage.... Gross!


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## Windows on Wash

Do not spray foam or seal that gap.

If you do, you will effectively be interrupting what is supposed to be part of the drainage path of the wall and in doing so, will create a rot issue in the structure and sheathing.

If you are having issues, the better thing to do would be remove some of the interior drywall and seal the back side of the wall or to install a z-bar flashing that would be tight to the sheathing (behind the WRB) and tight to the underside of the siding so as to deter the critters.

Mice are tough little buggers and will get into nearly everything but you can slow them down.


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## Peter D.

Alright! I won't! Thanks for the reply. 

I'm going to open that wall and see what I find. I'm sure it won't be pretty.


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