Horizontal Foundation Crack

[GhieBau]

Hello! Hoping someone can answer this question. I found a horizontal crack in the foundation, 6 to 7 feet in length, 3/16 of an inch in its widest point. I just want to verify if silicone is adequate to fix this as advised by the contractor? Thank you for the guidance.

 

[r13]

I think you need to figure out the cause for the crack before taking any action. Is this happened to the base mat of a spread footing, or mat foundation? What is the age of the concrete, and when the crack was noticed? Temperature at concreting?

 

[GhieBau]

Thank you for responding! This is on the beam in the crawl space of a 32 year old home. The crack was noticed recently during an inspection for this home that we are planning to purchase. Location is in Northern California. We requested seller for repairs but his contractor said they will just use silicone.

 

[r13]

It looks like the crack is located 1/3 of beam depth measured from the top. How close are the start and end of the crack to the support on each end, or it is occurred in between the supports? Also, was the beam cast monolithically with floor slab? Does it show excessive deflection? At this moment I couldn't come up any good reason, but am quite sure it lacks vertical reinforcement (stirrups).

 

[GhieBau]

Beam is seated on the ground (crawl apace). Crack is near the end. Wood floor sits on top of the beam. There is no new addition or added weight on the part of the house. It doesn't show excessive deflection.

 

[oldestguy]

I'd not worry about it. It appears to be a shrinkage crack at a zone of segregation during placement. If there is no noticeable settlement, great. A view from somwhat farther back might help.

 

[r13]

Yeah, it got me, I don't know why a grade beam will split like this without noticeable deflection. I would like to hear opinions from our experts here.

 

[GhieBau]

Thank you for the input! Hoping to hear what others think as well.

 

[kipfoot]

I'd suggest you find a local structural engineer who can evaluate the house in person. (I'd say it's better to do nothing than use silicone caulk.)

Alternatively, depending on your market, buy the house anyway and deal with it after you move in.

 

[r13]

Agree with kipfoot. If there is no indication of settlement around the building, and no noticeable deflection inside the house, I think you can take the chance if the price is right, thinking that you'll likely/need to deal it later.

 

[Agent666]

If in doubt get a local engineer to look at it and give you some advice/opinions. I'd say silicone is not an appropriate repair method typically for what looks like a significant crack. Might as well stick some duct tape over it and call it repaired.

Concrete doesn't crack for no reason, and could be indicative of larger issues in the future with respect to durability or it could simply be nothing.

There looks to be further cracks below for example. Get someone local to personally inspect it and if necessary remove some cover concrete to inspect the condition of the reinforcement. If warranted get a specialist concrete repair contractor to comment, I'd expect they'd be horrified if you asked them to use silicone as a repair strategy.

By the way this site is intended for professionals discussing engineering, not for generally soliciting free engineering advice.

 

[Ron]

Agree with OG...Lack of consolidation and some segregation. Looks like it was placed in separate lifts, so might be somewhat of a cold joint. Repair should be with epoxy injection. Silicone is worthless for this.