最初由 渐渐 发布
I didn't realize that was a tough question. 
OK, here comes my next question: what does it mean to me, a regular homeowner? Explain it to me as I'm a 6 years old. For instance, I have a small crack that goes from the basement floor all the way to the window side of the wall, about 1m from the floor, in what you described "longitudinal direction". OK, so if it's indeed caused by thermal load (??) or contraction, what does it mean to me? Is it a serious crack or can I simply forget about it?
Okay let me try. First I'd like to know more details: how old is the house? when did you find the crack? in year 1? Is it stable now? I mean, stop growing? How wide is it? just a hair crack, or several millimeters?
I assume your house are 6 yrs, too
. it's the same age as my house. Mine has some cracks in the basement as well but they're all from the first year, when the concrete was hardening and the subsoil was settling. It could be caused by both the settlement and the contract of the concrete because the crack starts from the slab and extended to the wall ... sorry, teh words after "because" are always boring
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Contraction of contract is normal. Most of it happens in the first month of pouring so. The hardening of concract contributes the most part of the so called "themal load" so it will be over in the first month as well. It means cracks caused by contraction will become stable in the first few months following the construction.
about the uneven settlement, don't worry if it is small and stablized soon. Normally it will become stable in a year (depends on soil condition, I assume you're in Kanata -- not Hunt Club South), after that period there'd be no more significant settlement. Any cracks occured in that period would become stable.
If you didn't find any leaking in another year, I suggest you fill the crack with cement and do whatever you want (stain the slab, put on driwall, etc.) to your basement. In my case, the cracks were filled with some kind of filling from HD, and they've never opened again in last 5 years.
Again, small, stable cracks in old houses are not a big issue. You may want to 1) maintain a positive grading, 2) downspout discharging should be at least 2m away from the house, and 3) watch any modification in landscaping (filling or excavation, because it may change the lateral earth pressure). 1) and 2) is to prevent water damage, and 3) is to avoid structural damage.
Are there any more tough questions waiting in the stack? I'm scared...
