The inspection for water seepage into the basement or crawl space should begin during your exterior inspection. As you walk around the house, record on your worksheet the location of those conditions that can cause water to accumulate around the foundation: faulty gutters and downspouts, improper grading, settlement of walkways, and so on. When you go into the basement, if there are problem conditions on the exterior, the walls and floor opposite those areas should be checked first for signs of water penetration. Figure 11-6 shows water stains and deposits in the corner of a foundation wall as a result of a faulty downspout. Even if there are no indications of past or current water seepage, the exterior problem conditions should be corrected.
A basement can have a water-seepage problem and be dry when you look at it. Many clients have told me that there were no seepage problems in the basement. After all, they looked at the basement during a heavy rain and found it “bone dry.” So how could there be a problem? Well, as previously discussed, there are many causes for water seepage, and depending on the cause, a single rain might not result in seepage. For example, if water penetrates into the basement through the floor slab as a result of a seasonally high water table and the basement is inspected when the water table is 1 or 2 feet below the high level, a heavy rain will not raise the groundwater level sufficiently to cause water to seep through the floor slab. It takes time for rainwater to percolate into the ground and raise the water table.
Water puddles or flooded areas in the basement are obvious signs of a water problem. In most cases, however, you will not see standing water, and you must then make an evaluation of whether there is a condition of water intrusion based on other, more subtle signs. Water-seepage signs indicate only that water has seeped into the basement in the past. They do not indicate the frequency of the seepage or its extent. Consequently, if you see indications of water seepage, you should not engage a contractor to waterproof the house immediately upon taking possession. If you do, it could prove quite costly.
First talk with the homeowner about the condition. It is possible that whatever it was that caused the past seepage has already been corrected. (If the problem was corrected by installing buried drainpipes or coating the outside surface of the foundation wall, the correction would not be visible.) If the homeowner indicates that the problem has been corrected, you should ask to see a copy of the paid bill. Or get the name of the contractor so that you can call to find out exactly what corrective steps were taken. Quite often a contractor provides a guarantee against water seepage. If there is such a guarantee, you should find out whether it is transferable.
The possibility exists that even though there are signs of water seepage, the actual seepage might occur very infrequently-such as only after an excessively heavy rain as might occur every few years. In this case, depending on the extent of the seepage and the projected usage of the basement, costly waterproofing measures might not be justified. The best approach when considering the correction of water seepage is to correct immediately any obvious problem conditions such as faulty gutters and downspouts, improper grading, cracks through which water is actively leaking, and so on. However, before undertaking any major water-seepage control measures, such as excavating and coating the exterior surface of the foundation wall, inserting perforated drainpipes below the floor slab, or trenching and installing buried drainpipes in the yard, you should live in the house for at least one full year. This will enable you to evaluate the degree and extent of the seepage over a full weather cycle. If it turns out that the year is particularly dry so that there is no seepage, well and good. Wait another year. By not taking a “shotgun” approach and waterproofing everything, as recommended by many contractors, you might be able to resolve the problem at a cost that truly reflects the work needed to stop the seepage.