The recent quake in the DC area got me thinking about this. I heard that someone that lives not too far from me had a crack in their foundation due to the quake. My basement is finished so, unless there is drywall damage or I pull up the carpet to look for cracks, how can I possibly know if the quake caused any structural damage? Are there companies that look into this or (I doubt) some telltale sign to look for other than cracks in the wall?
I live in the midwest, and we noticed a crack after an earthquake a couple of years ago. I called two different local “basement systems” places. Both took a look and said it was no big deal (one guy took almost two hours to come to this conclusion, delighting my husband with his thoroughness but driving me to the brink of insanity with rage.)
It’s virtually guaranteed that those cracks were there already and you just didn’t notice them. This happens all the time with urban construction. Someone feels shaking due to pile driving and starts looking around. They notice a crack that’s been there for years and assume it was the construction.
Yeah, there are thinsg you could do. Find accelerometer/particle displacement values for your area, assume that the top and bottom of the wall moved opposite of wach other at the same time, calculate strain and compare it to fracture strain of concrete. That’s a very very crude way of going about it. It’s also worst case, so if the strains are too small, you can rule it out.
You should look for a Licensed Professional Engineer in your area who advertises residential/home services. Do NOT choose a “home inspector”, who almost certainly has no actual Engineering background. In my area for about $500-$1,500 a PE will inspect your foundation completely, usually taking measurements with laser levels and other tools, then write you a 1-5 page report which will be stamped with their State seal.
And yes you are going to need to give them access to view the concrete walls, floors, and possibly the ceiling as well.
Assessing foundation damage yourself is very tricky unless you have a lot of education and experience, or else an enormous amount of construction-specific knowledge. I’m a Licensed Professional Engineer myself, and I wouldn’t stamp anything about my foundation as I do not have specific experience in that area.
Tie a six-foot string to any object. Hold the end of the string at the top of each wall in your largest room and dangle the object. If the object comes to rest within a half inch or so of the wall, probably nothing was affected as far as plumb. If it hangs a couple of inches away, as it did in our house in Anchorage, your pictures just aren’t going to look right, but your house is probably structurally okay. It takes a lot to seriously damage a wood-frame building. For foundation, I’d hire somebody. Not all cracks are terminal and may have been there for years due to past settlement.
Similar situation, same location. The twist is with the rain from the hurricane, I’m getting water seeping thru that crack. I am more than willing to concede I might not have noticed the crack before. However, I look at that wall during all heavy rains and haven’t seen water there before. My first check was for the gutter extension at that end of the house but they were in place.
There are cracks and then there are cracks(!). If it’s a masonry wall and water is coming through, then it’s more than a spall or stress crack and should be looked at. If it’s sheetrock, it could be wind-driven water that is coming from your roof somewhere and leaching out where it’s convenient.