House has "sunk" towards one corner since construction in 1966

[kgold]

A house that I purchased up may need some foundation work. I'll start off by saying that I will be bringing in a specialized consultant however in the meantime I'd like to learn more about this kind of issue.

The house is a 1966 bi-level (raised bungalow) in central Canada. It has not been updated or taken care of much since the previous owner acquired the house in 1973. Specifically, the conditions of the eaves-troughs and downspouts are abysmal and it is reasonable to assume that drainage has been poor and lots of water may have pooled in the back left corner for 10+ years. Using an automatic laser level, I determined the house is sitting at 0 inches in the front right corner; -2 in the back right, -1.5 in the front left, and -4 in the back left. As this is a raised bungalow, the footings are only about 4' down and this puts them close to the frost line at this location.

All the obvious signs of settlement are present however they are far less dramatic than you'd expect for such a high level of sinkage. There is minor drywall cracking around some windows and doors. The concrete slab has cracked such that it fell with the footing in the back left corner. About 8' from the front wall, the slab's first cracks are present and from there it slopes gradually to the low corner.

The foundation wall does have a crack in it along the left-side wall however it is less than 1/8th inch wide. It appears as if the entire foundation rocked down and back towards that corner over the years, and brought the upper level of the house with it.

Ideally I would like to level the house but it may not be worth it if I could safely say it is no longer sinking. I think the first place to start will be with a soils/structural consultant however I'd appreciate it anyone has any ideas or input on what could be going on here. I think it has to do with the drainage issue and perhaps a soil issue (improper digging/backfill which was not compacted).

Are there things to look for that will indicate if movement has stopped? What would be the best way to resolve this issue? Underpinning comes to mind. The soil appears to be OK under other houses nearby as they have not moved in the same manner. Another option we've considered (if we can safely say it is no longer moving) is to jack up the house and shim it on top of the foundation.

Again I appreciate your input and if there is any other information you need to comment, please ask as I am hoping for several perspectives.

 

[kgold]

Well, here we go.

Two contractors visited the house and we talked underpinning the foundation, raising and leveling the house on top, etc. Their perspectives were good to hear. I'm not going to go into more detail because the most interesting thing I found out today is that the house was already underpinned... in 1974.

The seller had disclosed there was a "1974 foundation repair" but it appeared to be written as justification for the presence of water seepage. I can't explain how I didn't get any more details upfront without describing our real estate market and property disclosure statements in detail. Regardless, the end result is the same.

I called the seller and I asked him about the situation with the house. He is old and is not a technical guy so I had to decipher what his meaning was but its quite plain to me that right after he bought the house in '73, he "brought in one of the big foundation guys because the house had sunk" and they poured concrete piles under this corner of the house. He seemed to recall there being 2-3 holes that they poured into somewhere near the kitchen (oddly... the kitchen is in the middle of the house along the back wall).

So this explains why the house doesn't appear to have moved in so many years. It also means the house isn't going to come back up without breaking it off from the 1974 underpins. I don't think they would've tried jacking back then so I think the piles were put in place to stop the house from any further settling.

I'm still trying to piece together in my head how this all would've played out back when he bought the house... my first guess is that they got a good deal on it because it had "settled" so much in that corner. They probably didn't notice it until after moving in. When they realized they had a bit of a problem they called the first foundations guy they saw with an advertisement. I highly doubt any sort of an investigation was done.

I'm pondering what my options are.

 

[kgold]

Jay - there is a single-lane asphalt driveway along this side of the house that ends at the back corner. The neighbours mentioned that it was put in place after they moved in sometime around 1990.

 

[jayrod12]

Well your situation just keeps getting more complicated I guess.

It is impossible to know what was actually done in terms of underpinning without seeing any drawings or anything like that, and since the regulations back then were a little more lenient I doubt a building permit was ever pulled for the foundation repair. you are correct in your point about they won't be able to level the house without abandoning the existing underpinning job.

Depending on what the foundation guys you had in said it would be worth contacting a structural engineer (in fact it will be required if you are doing any work) once you've narrowed down your proposed fixes.

If you're certain the house isn't moving anymore then remember there's always the option of leaving it as is. I know that doesn't resolve the slope to the house however if the slope is tolerable it may be worth leaving it well enough alone.

And in regards to the driveway, if you were noticing heaving in the winter and sinking in the summer along the wall next to the driveway then you would have a frost issue. If you don't notice anything like that then you're probably ok from a frost perspective.