Horizontal Crack Around Basement (Not Frost Heave)

[zero1238]

I inspected a house on the beach in NJ this past week, which was a 1-story dwelling with a basement, constructed fully of masonry block. When I went into the basement, there was a horizontal crack about 36" above the basement slab (and near outside grade level) which propagated through the mortar joint and extended around all four perimeter walls at the same elevation. What was most interesting was that the mortar looked like it was being pushed out and when I took a vertical profile of each wall, it was not leaning or displaced inward, which is usually what I expect when I see these types of horizontal cracks. Additionally, I believe I ruled out a settlement issue from the level measurements that I took. When I removed a dislodged section of mortar that was sticking out from the wall, I found what looked like a piece of corroded steel between courses. The house was constructued in 1940 but could this be some type of bond beam or other reinforcement that could have corroded because it was near grade level and then pushed out the mortar due to corrosion volume expansion? I'll attach some pictures below. Also, any thoughts on a possible fix? I'm thinking of having them scrape out the oxidation from both interior and exterior sides, epoxy sealing it, and then repointing but I've never come across this before.

 

[TRAK.Structural]

Could be horizontal joint reinforcing that has corroded as you mentioned, not sure if that would be common for residential construction in the 1940's. If there is not lean or displacement/offset on the vertical face of the wall than I wouldn't be too worried, however without a more robust waterproofing solution it may be difficult to prevent further corrosion and subsequent damage.

 

[Alban1an]

It could be that the Crack propagation is due to the outside ground freeze/thaw cycle swelling, and the fact you don't see inward slant is because it's not due to (constant) pore water pressure but rather the expansion from ground freezing at some point in the past. That horizontal joint probably did it's job until it corroded and then it didn't which exactly where the Crack developed aided by water intrusion.

 

[JoshPlumSE]

Could it just be that the reinforcing was place in the mortar joint (ladder reinforcing) too close to the face. With a little moisture and corrosion and you'd get something like that behavior. What about on the outside of the wall? Can you see similar damage? Maybe you have to excavate a little to check?

I'm not really a Masonry guy. But, I have to think that if the mortar is messed up on BOTH sides of the wall then this would be a problem. There might be a simple solution. But, at the very least I think the recommendation would be to knock out and replace any loose crack mortar and where it isn't that damaged maybe an epoxy injection into the crack?

 

[zero1238]

This is exactly what I was thinking. I can't see any damage from the outside since it's below grade but I'm going to have them excavate it. Definitely need a good waterproofing company.

 

[MintJulep]

Maybe it was originally a rubble foundation, replaced with block sometime after the house was built.

 

[dik]

What are the soils? expanding clays? Sounds like flexural crack from lateral loading. What is the exterior drainage like? Can you use epoxy injection?

 

[jerseyshore]

I inspected a house on the beach in NJ this past week

How come you didn't say hi?

I've seen a few of these exact situations this year. It's most likely shoddy dur-o-wall that rusted out and pushed the mortar joint out. Poor grading/ drainage/ waterproofing at grade level allowed water infiltration and the rusting to begin. Reinforcing issues are always more prevalent in the shore towns because of the salty air. I've seen this once in 15 years up north, but much more common along the coast.