Understanding the most common foundation problems and knowing the underlying cause of each will help you make an informed buying decision. Below are the most prevalent foundation problems according to professionals I’ve spoken with.
Every home foundation cracks at some point. Most homes have hairline cracks that formed during the natural settling process of the concrete after the foundation was poured. These appear as very thin fissures running vertically up and down the foundation walls. Generally speaking, these gaps are harmless, although most homeowners choose to seal them to keep water and moisture from seeping in.
Horizontal or stair-step cracks on the basement walls of a home are far more problematic. If you discover these during a walk-through of a property, you should know that you might need to pay for stabilization and repair in the future.
Horizontal cracks on the foundation walls develop when the pressure from the soil outside becomes too intense for the concrete to resist. This is a common occurrence in our area because the soil often contains clay and bentonite, both of which are more absorbent than other types of soil, and expand when they get wet.
We can expect up to 60 inches of snow each year, and when this snow melts, the soil around your home gets saturated. The highly absorbent clay can expand, at which point it puts intense stress on your foundation walls, sometimes causing them to crack.
Stair-step cracks occur most often because of the differential settling which occurs when different parts of the earth beneath a home get wet and dry out at different rates. This is typical in an area like ours, where the soil can expand rapidly even from being introduced to minimal amounts of runoff.
Eventually, an unsupported section of a foundation cracks away from the rest of the home and leaves a step-shaped crack, which usually indicates structural damage.
Concrete is relatively rigid, but an eight-foot wall can flex slightly before cracking under the pressure from the soil outside. If there are signs that they’re bowing inward, the wall is at risk of cracking and losing its structural integrity. Just because a foundation may be slightly out of plumb, however, does not necessarily mean it needs repair.
Although it stands to reason that a bowing wall is easier and more affordable to correct than one that has flexed to the point of cracking, the repair process is roughly the same and just as expensive.
Water intrusion is a pervasive issue. Water can enter the basement through cracks in the concrete or directly through the pores of undamaged concrete. (Because concrete is porous, it’s a common practice during construction to seal the outside of the foundation with a black coating which you may have observed.)
While you’re inspecting a home, pay attention to visible water in the basement, musty odors, visible mold growth, noticeably damp air, and efflorescence on the walls. Efflorescence is a white, powdery substance that gets left behind by intruding water.
When basement walls have been finished, it’s not possible to observe any cracks within a foundation wall. However, there are usually other indicators that may be visible, such as upstairs windows with cracked glass or that are difficult to open and close, interior doors that rub on the frame or will not close, irregular cracking within the walls or ceilings and/or under windows or around door framing, sloped floors, etc.. These are a few conditions that could indicate a foundation issue.
Homes with cinder block, brick or rock foundations are far more susceptible to water damage and/or movement from expansive soils as they are unreinforced.
Also worth inspecting is proper drainage, downspout extensions and inadequately designed or improperly installed gutter systems, vegetation (trees, shrubs, grass, etc.), sprinkler systems and planters, etc. All of the aforementioned could cause cracks in a foundation.
No one should buy a home without hiring a professional inspector, even if you have waived some of your rights to demand repairs. A professional inspector is typically not a structural engineer, but he/she will recognize indicators that you should hire a structural engineer to make a separate assessment of the foundation.
When you’re purchasing a home, you should be confident that it’s structurally sound and won’t end up costing you thousands of dollars in repairs.