There are several warning signs that home inspectors can look for on the interior and exterior of homes that may point to problems or possible future problems with foundations. Almost all houses settle over time and a few things being out of level should not be a cause for panic. However, there are warning signs that there could be larger problems. Knowing the early warning signs of foundation troubles can head off problems that could be very expensive to remedy. It’s a common mistake to treat the symptom (filling in a cracked slab, for example) instead of addressing the soil or construction details that caused the damage. When this superficial strategy is used, foundation damage usually recurs and worsens.
On the exterior of the home inspectors can check to see if the foundation is straight by looking down the length of the foundation wall from each corner. The walls should be basically straight, both up and down and from side to side. Check for leaning walls with a level. A bulge or curve in either a block foundation or a poured concrete wall could signal that the foundation has shifted, or that the soil around your foundation may be expanding and contracting, putting pressure on walls.
Some of the interior issues are, cracks that appear in walls when foundations are moving especially over doors and windows. Doors that begin to stick or no longer latch properly. Cracks can also appear in ceramic tile of concrete floors. Windows that used to operate normally can begin to stick or not close completely.
Not all foundations are visible due to basements being finished. However, when visible almost all will have at least a few cracks. As concrete cures, it shrinks slightly. Where the concrete can’t shrink evenly, it tends to crack. Hairline cracks are not a problem. Stair-step cracks in masonry joints are a bigger concern, especially if the wall is bulging or the crack is wider than ¼ inch. Horizontal cracks are the most serious. You may have soil that expands when damp and shrinks when dry.
Foundation systems have other components besides the foundation wall. There can be posts, metal piers and/or concrete supports in your basement or crawl space. Piers or posts should stand plumb and be firmly planted underneath the beams they support. The base of the posts/piers should rest firmly on concrete pads. There should not be any moisture in basements or crawl spaces. Check for rot by probing exposed wood with a knife or screwdriver.
Here is a list of some of the things an inspector will look for while inspecting a foundation or that may warrant further investigation. Some of these might require the expertise of a structural engineer.
• Cracks in foundation walls or floors that include displacement (sinking, heaving or shifting).
• Cracks in walls or floors that change in size.
• A wall that bows or tilts inward.
• Stair-step cracks in concrete block walls.
• Uneven, sinking or bouncy floors above a crawl space foundation.
• Cracked brick on a building exterior.
• Concrete slabs in basement floors that have cracked and shifted or settled.
• An exterior precast stairway that has sunk or shifted.
• A tilting chimney.