Are unlevel floors always a sign of some sort of structural damage( framing, floor joysts etc) ? Or are there other causes? If so, what are they?
There could be structural or foundation damage. Or it could be the house settling unevenly. It depends on what you mean by unlevel. Are the floors perfectly straight just tilting off to a side. Or are the floors warped, bowed? Or are there lips and noticable bumps? If you are looking at a house to buy, you might want to pass or have an expert look at it. If you own the house and want to repair, you will probably want someone skilled to look at it.
Old houses have unlevel floors and walls, it sucks when remodaling. But besides that, they are still pretty structuraly sound.
Could also be caused by a failure of a piling. Or b/c the piers (if a raised house) are sinking, house can dip. We had a house that was doing that, non of the piers down the middle touched the floor joists.
usually it is caused by shifting foundations or support columns. Alot of times the foundations were never strong enough to hold the weight especially the center support columns. the exterior walls hold up and the heavy wieght of the house sinks the undersized support column that probably has no footing into the ground.
not always structural damage but could be: 1) shifting foundation (mostly due to changing moisture content in soil around house) 2) bad workmanship when installing the floor or support structure. 3) thermal growth/shrinking of material 4) bad design of support structure... support not sized properly for the load that it is supposed to carry. 5) moisture content of the flooring materials can cause it to grow or shrink. I'm sure there are many more reasons.
