The house is fifteen years old, with an asking price a little below market value. The exterior walls and roof are in good shape, the landscaping is attractive, and the driveway is free of defects. Inside, the rooms and kitchen are in good condition, with plumbing that doesn't leak, good insulation, and a furnace and central air conditioner that function well. A prospective buyer carefully looks around the house, and concludes that it is a terrific buy. Or is it? What this shopper doesn't know is that the house's foundation was poured in freezing temperatures and the concrete was not adequately heated, resulting in improper drying. Two-inch cracks in the foundation, which the potential buyer saw but didn't give a second thought to, indicate a foundation problem that is potentially serious and expensive to rectify.

The foundation tends to be one of the most overlooked aspects of a house because it's mostly underground-out of sight, out of mind. A foundation inspection is prudent because problems can be identified before buying a home, saving you (potentially) thousands of dollars in repair costs. If you are a homeowner preparing to sell your house, confirming that your foundation is in good condition (by a certified home inspector) and providing written proof will help your house sell. If a foundation problem does exist, at least you will know what it is before your house goes on the market, and you can take action to have it fixed.

How can you determine if a house has a foundation problem? The following are some signs:

1. Signs of rot or insect infestation close to the foundation.
2. Inconsistent soil compaction around the foundation. Problems can occur when soil has not been compacted properly, resulting in an uneven settling of the house over time.
3. Improper soil around and underneath the foundation. This has been a problem mostly with newer homes (five years or younger). To save money, some builders have used poorer quality soil, which can sink (compress) or shift when the soil becomes wet. If you are building a home, ensure that your builder uses good quality soil around and underneath the foundation.
4. Foundation cracks. Check the exposed concrete outside (above the ground), and inside the house on the walls and floor. Depending on the size and number of cracks, there may be a foundation problem.
5. Significant cracks in brick and mortar, and leaks and cracks around the fireplace.
6. Cracks in interior walls near corners of doors or windows. Where walls meet walls, ceilings or doors, are they pulling away from each other?
7. Nails coming out of drywall surfaces and/or corner frames.
8. Separating or curling wallpaper.
9. Caulking that is separating from exterior surfaces.
10. Doorsills that are separating from their frames.
11. Windows and doors that don't move easily. Open and close all windows and doors in each room. Do they fit without sticking or binding?

While most houses have a foundation made of poured concrete, some foundations have been made from block, and even stone. A poured concrete foundation is best because there tends to be fewer moisture problems than with a block or stone foundation. Be sure to find out what type of foundation is supporting the rest of the house. Check for good drainage away from the house around its perimeter. Do the downspouts take water away from the home? Surface drainage next to the foundation should slope away about a quarter inch per foot. Also, ask about the underground drainage pipe (also known as weeping tile). When was the last time it was inspected?

For many older homes, the underground drainage pipe was made of cement and over the years, rain and melting snow leeched the cement's chemicals, weakening the pipe. The water table would rise when it rained or snow melted, and water from the downspouts would go into the pipe. Eventually, the drainage pipe would not be able to adequately take the water away from the house and the water table would rise beneath the foundation floor. A large crack in a foundation floor is a sign of this type of hydraulic pressure, and evidence that the drainage pipe around the house probably needs to be replaced.

If you're looking at a home and see cracks in a foundation wall, be aware that cracks are not always an indication of a problem. Often basement wall and floor cracks are nothing more than hairline fractures caused by shrinkage during the curing process. Such cracks are usually insignificant. However, if they leak water or appear to widen as time passes, it can be an indication that a problem is developing. If this is the case with your home, consult with a foundation repair specialist. If you're shopping for a house, be sure to have an inspection done by a certified home inspector who, for about $300, will examine the foundation (and the rest of the home) to determine if there are any problems.

If you do have a foundation problem, do not postpone getting it fixed for too long. The longer you wait, the more costly the repair will be. A foundation problem will decrease your property value, make your house difficult or impossible to sell, and can cause health problems due to mold resulting from excess moisture. Taking action to ensure that your home's foundation is in good condition will not only give you peace of mind, but will maintain the value of your investment.