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The home inspector should take note of:

  • un-level flooring;
  • cracked tiles;
  • sagging floor joists;
  • evidence of wood-destroying organisms;
  • treatment holes for wood-destroying organisms;
  • joist or sub-floor rot;
  • sistered or repaired joists;
  • evidence of missing joists that should have been installed or were removed and not replaced;
  • evidence of missing joists under load-bearing walls;
  • cracked joists;
  • signs of deflection, and a noticeable bounce to floors;
  • squeaking floors;
  • wood in contact with concrete;
  • poor joist-end bearing;
  • inappropriate notching or holes in joists;
  • joist splits;
  • over-spanning or under-sized joists;
  • joists too close to grade (soil);
  • over-spanned or under-sized sub-flooring; and/or
  • swollen wafer board or OSB sub-flooring.

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:

  • Double joists should be installed under parallel bearing walls.
  • Maximum holes should not exceed a third of the height of a joist.
  • Holes should not be within 2 inches of the top or bottom of a joist.
  • No notches should appear in the middle third of a span.

General rules about prefabricated I-joists:

  • There should be no notching of either flange.
  • There should be no big holes or notches in the ends of the joists.
  • There should be no holes within 6 inches above a bearing wall or girder.

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.