Remember the story about the wise man who built his house on the rock and the foolish man who built his house on the sand? When the storm hit, only one house was left standing.

The foundation is the single most important part of your new home. The house itself may look perfect, but if it isn't built on a solid foundation, your dream home could become a nightmare.

Most damage to the foundations can be fixed, but repairs are expensive.These are some things to look for when separating the wisely built houses from the not-so-wisely built. If you are serious about purchasing a house but unsure of its foundation, consult a professional.

Climate

Foundations must be right for the soil beneath them. In colder climates, a foundation's footing, the part that bears the weight of the house, should be set below the frost line to protect it from frost damage.

Foundations are usually made of concrete, but in older houses they may be made of stone or brick or even wood.

Water

Water poses one of the biggest threats. Check outside the house to make sure the soil slope runs away (highest at the house); otherwise, when the rainy season hits, you may find your house in the middle of a lake. If the house is built on a slope, check for a drainage culvert to divert water around the house.

If there is a basement, check for musty odours and other telltale signs of water damage. If the basement is unfinished, look for a white powder on the walls and along the floor. These are minerals, deposited by water as it evaporates, a sure sign of a leak.

Cracks

If a house settles too much, the foundation can crack, causing all sorts of problems. Check both the exterior and interior for cracks. Anything larger than a quarter of an inch wide is cause for concern. Vertical cracks in concrete or step-cracks in brick or concrete blocks indicate settling damage.

But if the crack is horizontal and located in the basement, it is likely caused by expanding soil - unchecked, it could lead to a collapsed wall.