Watch HouseSmarts in November to learn how to make these cool envelopes.

As much as we like to curse them, basements and crawl spaces are crucial to maintainingthe health of your house. First, the concrete or mansonry in the walls separates the damp soil from the wood frame – which would otherwise decay and quickly turn your home into an insect condo. Even more important, these foundation walls literally shoulder the weight of your house and hold up the entire structure.

Whether made of concrete, bric, stone, or cinder block, the walls take the weight of a fully loaded house – which can easily top 100 tons, give or take a grand piano – and transfer it effortlessly to the ground below. What gives the walls this amazing strength is their shape. The base of the wall, which is buried in the ground beneath the floor, widens to a 16-inch poured concrete block called a footing. These footings distribute the weight of the house over a broader area than the walls alone would, and by doing so prevent settling or movement of the structure above.