Foundation Cracks - What's Normal?

In discussing foundation cracks, the type of foundation under discussion must always be considered. The two primary modern day foundation types are constructed using poured concrete and concrete block or cinder block / cinderblock.

Cracks in Poured Concrete Foundations

Over the years we have concluded that, on average, there are 7 to 10 cracks to be found in a poured concrete foundation of a 2400 ft² home. This number of cracks is normal. Abnormal and structural cracking is discussed elsewhere on this website.

Note: In addition to basement leaks attributable to foundation cracks, you should expect to have a number of tie-rod holes in need of waterproofing.

Cracks in Concrete Block / Cinder Block Foundations

If you have a concrete block foundation it is quite common to have many fine hairline cracks in the mortar joints between the blocks, and sometimes cracks of varying width in the blocks themselves. Most cracking of concrete block walls is attributable to improper drainage around the perimeter of the home, seasonal expansion and contraction of the soil which puts pressure on the walls, and cracking in mortar joints caused by thermal cycling of the mortar and the concrete blocks being bound together. Regrettably, concrete block foundations deteriorate over time; consequently, the probability of developing a basement leak increases with each passing year.

Note: Horizontal cracking in concrete block foundations provides clear evidence of foundation failure. This issue is discussed further on the Concrete Block Reinforcement page.

Tip: To avoid headaches in the future, due to basement leaks, we strongly recommend that you call us to arrange for a foundation inspection prior to finishing your basement.