Floor level survey for cracks
The short story:
I have some cracks in my wallboard and, in an attempt to figure out what is causing them, I did a floor level survey. My question is:
If I were to repeat the same survey in a few months or a few years, what magnitude of changes in elevation would be acceptable / unacceptable?
The much longer story:
- Our house is a tract home from the late 50Âs (cheap construction - but good quality lumber).
- I did the floor level survey using a water level and made an attempt to account for different floor thicknesses in some of the rooms (carpet vs. new/old hardwood vs. linoleum).
- There is currently a maximum 1.5 inch difference in level between one side of the house and the other but no significant abrupt changes over small distances. I imagine there is no sure way to determine whether these level differences existed since the house was built or occurred later on?
There are no cracks in the foundation. (We have perimeter foundation with crawlspace and additional foundation walls below weight bearing inner walls, no posts).
I do though have one somewhat large crack in my kitchen ceiling 1/8" to 3/16" wide and 5 ft long between wallboard sheets. I had put pencil marks on the crack 10 years ago and there seems to be almost no active movement. I checked the foundation below that area more carefully and I can see no cracks or dislocations. Also, the floor level survey did not reveal any abrupt changes in floor level in the vicinity of this crack.
I also have some smaller (less than 1/16" wide) cracks in a few places between wallboard sheets and a few narrow but short (4" to 12") diagonal cracks around two doors. These smaller cracks seem to have grown a little over the past 10 years.
So far, I suspect that the cracks are caused either by house settling/seasonal ground movement/gradual ground movement OR by some insufficient bracing on the roof corners/ceilings (I will not get into that because it would be hard to explain without a diagram). For the large crack on the ceiling, I also suspect some sort of failure in one or more of the adjacent bathroom joists. I am planning to rip the floor in that bathroom to remodel anyway, so I will get the chance to take a better look at it.
In any case, the main purpose of my floor level survey is to determine (over time perhaps) whether it is ground shifting or roof bracing that caused (still causes?) the cracks and, of course, IÂm interested in taking the appropriate remedial action.