Do you have a knowledge of firm foundations when it comes to buying a house? Take this little test to help you tell.

1. It is normal for new houses to "settle." -- (a) true (b) false?

2. About -- (a) 5 (b) 10 (c) 50 percent -- of all new homes are built on expansive clays.

3. Expansive clay usually occurs in -- (a) black (b) brown (c) grey (d) red soil?

1. (a) True. This is mostly a one-time event.

2. (c) About half of new homes will suffer some damage. Repair costs can be 50 percent or more of the cost of the house.

3. (a), (b) and (c). Expansive clay expands and contracts with changes in the moisture level in the soil, pushing on the foundation of the house. Evidence of expansive clay includes -- tilted floors; large cracks in walls, especially in doorways; shrinking or cracking of dry soil into a honeycomb pattern; sunken driveways; and leaning trees.

If you think there may be structural problems, it's a good idea to have a house inspected by a structural engineer before you buy. A geotechnical engineer can test for expansive clay or other soil problems.