I have a concrete slab as a front porch on a property I recently acquired. This was put in when the house was built. At some point since it was put in, front sunk/settled and the slab separated from the house. It looks like previous owners attempted numerous patches (silicone sealants, concrete patch etc). The separation from the house allowed termites to enter and damage a 5 foot section of the rim joist along the front - there is no active infestation and we've determined the rim joist was the only damage.

At some point I realize I need to have the front porch torn out and the rim joist repaired. However, in the short term I'm looking for the best way to patch the concrete and mitigate further damage to the joist from moisture or critters coming from the crack. What would be the best thing to do?

Porch Separation

View from the side showing the separation/tilt

1 Answer 1


From the two pictures, it looks like the porch is two parts - the foundation slab, and the top surface. Is the slab moving, or just the top surface?

My suggestion would be to apply low-expanding spray foam (they make a grey-colored version so it doesn't look ridiculous, as well as one with pest deterring chemicals) to those cracks. If it expands too far out of the top-surface crack, trim it after it's try, then apply caulk to the face of it to waterproof it.

Continue to monitor it for movement going forward. It's important to determine how and why you're getting movement.

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