The home inspector should take note of:
Generally speaking, it will be rare to see joists spread more than 24 inches apart, but if this condition is discovered, look for any signs of a joist that may have been removed.
In rooms where exterior covered porches may have once existed, it is not unusual to find that sleepers and a new sub-floor were installed because exterior porch floors are often pitched away from the dwelling to allow rain water to run off and away from the home.
Home inspectors often notice a hump in the floor on either side of the beam underneath. This is generally caused by excessive joist overlap where the ends of an extra-long joist kick up. This “teeter-totter” effect also occurs with cantilevered joists when deck joists run through a wall, for example. These humps are not a serious structural problem.
Cracked tiles are usually the result of the sub-floor not being rigid enough. This is not a structural issue.
General rules about standard dimensional joists:
General rules about prefabricated I-joists:
Cracks in Concrete Floors with Basements
The concrete floor is not an integral part of the foundation and is often poured after the home is nearly finished.
Cracks in Slab-on-Grade
It is difficult to tell if slab-on-grade cracks indicate a structural problem, so all such cracks should be noted and reported.
Wood in Contact with Concrete
Sill plates on top of concrete foundations should be made from treated wood, or have sill sealers or separators between them. Wood beams embedded into concrete foundations should be treated.