Most houses built in the last forty years have foundation walls of poured concrete, concrete blocks, or cinder blocks, whereas older homes generally have stone or brick foundation walls. When inspecting stone or brick foundations, especially in homes built before or around the turn of the century, pay particular attention to the mortar joints. I have found that in homes of this vintage, many of the mortar joints in the foundation walls have deteriorated to a point where they are no longer functional. Some of the joints might have holes, and some may be filled with soft, crumbling mortar that can easily be raked out. In some cases, the joints between the foundation stones might have been filled with earth or mud rather than mortar.
Deteriorated mortar joints in foundation walls should be repointed, not so much because they represent a weakened structural condition (they do, but this is usually not a severe problem) but because they can allow water to penetrate into the basement (see FIG. 11-2) and enable mice and other pests to enter the area.
In some older homes with brick foundation walls, you might find soft, crumbled, and flaking bricks so badly deteriorated that they should be replaced. This condition is usually the result of using underburned bricks in the construction of the wall. Bricks that are under-burned during the manufacturing process are softer and absorb water more readily. If you see this condition, it should be recorded on your worksheet, since masonry rehabilitation is needed.
Cracks in poured concrete or con-crete-block foundation walls can result from shrinkage, differential settlement, lateral pressure on the wall by the soil, or poor-quality workmanship. It is not uncommon to find short cracks in foundation walls. These cracks might be vertical, horizontal, inclined, stepped, smooth, or irregular and are usually of no structural concern. All cracks, however, should be sealed as a precautionary measure against water penetration into the basement. Otherwise, if there should be a hydrostatic pressure buildup in the soil against the foundation, water will seep through the cracks.
If there are long narrow cracks in the wall and both sides of the cracks line up so that there is no noticeable differential settlement, it is usually not a serious condition and can be controlled by sealing the cracks. However, when both sides of the cracks do not line up or there are long open cracks, a more serious condition of differential settlement exists. Since it is not possible to determine from a single inspection whether the differential settlement is active or dormant, the wall should be checked for incremental movement over a period of time, usually several months. In most cases, after some time, the differential settlement stabilizes with little effect on the house other than functional annoyances such as binding windows or a floor that might not be level. However, because of excessive settlement, an unstable condition can occur either in the foundation wall or the wood framing being supported by the wall. If there is any doubt in your mind about the condition of the foundation wall, you should have it checked by a professional.
Another type of crack of concern is a long, open horizontal crack in the foundation wall, especially if the wall shows signs of bowing. This condition is principally caused by an excessive horizontal pressure being exerted on the foundation wall by the earth backfill and indicates that the wall cannot adequately withstand these external lateral forces. This condition should be recorded on your worksheet as a condition that requires further investigation or repair.
Structural support framing
Because of the vulnerability to deterioration from rot and wood-destroying insects, all exposed wooden support members (girders, joists, posts, and sill plates) should be checked for structural integrity. Steel beams and columns, on the other hand, need be checked only for degree of rust or corrosion. Usually the rusting is only a surface defect that can be corrected by scraping, priming, and painting.
Wooden support members should be probed with a screwdriver or an ice pick, as described in chapter 8. If the wood is in good condition, the probe will not penetrate much below the surface. The portions of the joists and girders that are most vulnerable to deterioration are those resting on or adjacent to the foundation wall. While probing these areas, you should also check the sill plate (which is anchored to the top of the foundation) for structural integrity. Many older houses have wood support posts rather than steel columns. If there are wood posts, check their bases for decay. The base has a tendency to rot because of periodic dampness or seepage through the floor. A post with a rotted base should be replaced. Joists with deteriorated end sections, however, need not be replaced. They can be rehabilitated. In most cases, all that is needed is to place a similar size wood member alongside the affected joist and secure it to the portion of the joist that has not deteriorated.