Foundation Crack Mystery Solved

**Bruce Breedlove** · 10-12-2007, 08:09 PM

This was an interesting exercize.

I got a call from an agent asking if I could look at the foundation of his personal house. He said he had a large crack in the garage foundation and several cracks in the ceiling of the house. The house is located in an area with expansive soils and landslides several streets away. The agent knows that I am an engineer and just wanted to get my opinion of whether he has a serious foundation problem.

The house is about 15 years old and the front faces uphill. The agent showed me a large vertical crack in the concrete foundation about 2 feet from the outside front corner of the garage. The foundation has been stuccoed and it was apparent the stucco at the crack had been patched at least once. (Not disclosed by previous owner.) There was no cracking in the stucco of the framed wall above the foundation crack. I found no other cracks in the foundation (other than normal cracking) until I looked at the other side of the garage. Interestingly, there was a large vertical crack about 2 feet from the front corner of the garage; only the top 3" or 4" of the foundation was visible at this location due to backfill.

The large, covered concrete front porch had rotated slightly away from the house and a concrete slab poured between the porch and the garage had dropped over 1" along the garage wall. The movement of the porch was not a concern. The slab dropped because the soil along the foundation subsided over time due to inadequate compaction (very common around here).

The cracks at the ceiling at the center of the house appeared to be normal cracking. There was no evidence of a foundation problem in this area (no cracks in the basement walls and ceilings and no unusual cracks in the walls of the main level). I determined that whatever was happening at the garage foundation was probably not related to any cracking in the house.

So I turned my attention back to the garage foundation. The cracks on both sides extended through to the inside of the foundation walls. There was no differential movement. There was a crack in the garage slab connecting the two cracks in the foundation walls. Then I noticed a few clues that helped me solve the mystery of the foundation cracks.

The inside face of the foundation wall has been saw cut just behind the crack on both sides of the garage. An anchor bolt is located well outside of the framed wall on one side and a 2X4 mud sill turns into the garage at the saw cut on the other side.

Here is the solution:

The foundation is not cracked. After the foundation walls were poured but before the walls were framed the garage was extended by 2'. Perhaps a buyer came along and wanted the garage extended so their SUV would fit. The builder saw cut off the return walls and poured the extended foundation walls. I told the owner there is no way to determine if the builder properly tied the original and new foundation walls and footings together (e.g., installing dowels) without further investigation.

So those were joints, not cracks. I told the owner it would be impossible to keep stucco from cracking at the joint (the 3' long wall expands and contracts less than the 50' wall).

Mystery solved!

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**Jim Luttrall** · 10-12-2007, 08:16 PM

Too bad they didn't put in a control joint for the stucco.

**Bruce King** · 10-12-2007, 08:25 PM

Sounds like you did a good job, makes you feel good huh?

My previous job allowed me many chances to solve major mysteries and that is all I miss about it. But this job has many good days too where different and weird issues come up.

Sometimes I look over foundation problems, record some notes, take pictures and continue the inspection with full intentions of going back over it and really thinking it through. The problem is when the client is wanting to know about it right now, I just tell them that I have not decided yet.

**Bruce Breedlove** · 10-12-2007, 08:28 PM

Originally Posted by Jim Luttrall

Too bad they didn't put in a control joint for the stucco.

I thought the same thing but it has not cracked in 15 years.

**Rick Hurst** · 10-12-2007, 08:40 PM

Regarding those water stains

**Jerry Peck** · 10-13-2007, 06:17 AM

Originally Posted by Bruce Breedlove

The foundation is not cracked. After the foundation walls were poured but before the walls were framed the garage was extended by 2'. Perhaps a buyer came along and wanted the garage extended so their SUV would fit.

Or ...

The builder's sub just made a mistake and made the garage 2 feet too short ... which created the need to do all that other work.

**Jim Luttrall** · 10-13-2007, 06:33 AM

This is what I was referring to.

The foundation has been stuccoed and it was apparent the stucco at the crack had been patched at least once.

Just a little control joint instead of repair and everyone would have expected and probably not noticed any movement.

"Buildings move, let them move" or something to that effect, Dr. Joe L.

**Bruce Breedlove** · 10-13-2007, 11:54 AM

I got ya now, Jim.

You know as well as I do that the builder almost always does the least possible. While a control joint at the construction joint may be the right way to go in the long run, compared to simply stuccoing over the joint it costs more, is more difficult and draws attention to the construction joint. Sure, the stucco will crack at the joint but the builder will be long gone by then and it will be someone else's problem.