A basement serves a dual purpose, as it is both additional living space and your home’s foundation. Any damage to the main basement structure is a cause for concern because the problem will eventually compromise the whole house. Learn about the most common basement foundation problems and how to recognize them so that repair plans can be made before the issues become too bad.
Inward Deflection
Also simply referred to as bowing walls, inward deflection is when the basement walls begin to bulge inward. This problem is more common on concrete block walls as opposed to poured concrete foundation walls.
Cause
External pressure is the cause, but there are a few sources that lead to this pressure. A high
water table that leads to saturated soil pressing against the outside of the walls— called hydrostatic pressure—is one of the more common causes of bowing. Expansive soil types, which contain heavy amounts of clay and swell rapidly when wet or frozen, can make the situation worse.
Even parking a heavy vehicle too closely to the foundation can lead to pressure and bowing. The weight pressing down on the soil is the problem, so keep heavy equipment away from your basement foundation.
Repair Options
Repair will depend upon the severity of the inward deflection. Minor deflection can often be repaired with the use of wall strapping or anchors, which will help pull the wall back while also preventing future bowing. Some types of anchors require excavation as they are installed on the outside of the walls, while tieback devices may be installed on the interior.
Sometimes replacement of the affected foundation wall is necessary, especially if it is bowed severely. You may also need to replace the wall if it must be removed to address issues with the soil near the foundation, such as poor compaction.
Concrete Cracks
Cracks in the basement walls should always be professionally assessed. Although some cracks are merely cosmetic issues, others can indicate underlying foundation trouble.
Cause
The location and type of crack will indicate whether it is something that must be repaired. Most vertical and diagonal cracks, for example, are nearly always cosmetic and don’t require repairs unless you want to improve the appearance of the foundation wall. They are caused by natural settling. It’s still a good idea to have these checked by a foundation contractor just to be sure, though.
Cracks to be concerned with are horizontal cracks or those that stair step along the joints of a concrete foundation wall. These cracks indicate that the basement foundation is shifting unevenly, which will compromise the structural integrity of the walls. Frost heave, expansive soil, poor backfilling, and hydrostatic pressure are the causes.
Repair Options
Cosmetic cracks only require a cosmetic repair. After a full inspection to verify there are no underlying concerns, your contractor will simply patch the wall. You can then paint the foundation walls to camouflage the repair so it looks nice in the basement.
For cracks that are structural, repair begins with addressing the cause. This may mean digging out the foundation, water sealing the exterior, and then replacing the soil around the foundation. Cracks may require filling and patching so they don’t become worse once the causes are addressed. Replacement is necessary only in cases of severe cracking and shifting.
Sinking Floors
A sinking basement floor can be alarming. Sometimes the floor seems to sink fairly evenly, while in other cases part of the floor sinks more rapidly. Cracking in the floor or where the floor meets the walls is also common when the floor is sinking.
Cause
There are a few common reasons a basement floor will sink, but often the problem is drainage. Drainage becomes a problem as erosion occurs beneath the foundation, causing voids to open up. Water can seep into these voids under a basement foundation if water draining off the roof or from upslope isn’t routed away from the home.
Poor soil preparation before the house was built can also cause a sinking basement floor. New construction is more likely to have this problem. If the soil isn’t properly compacted, it will settle severely in the next couple of years. Minor settling isn’t a concern, but if you notice cracks in the floor or where the floor joins the walls, or if window frames are out of square, there may be a problem.
Repair Options
Jacking the floor up to level and filling in the void beneath is a standard repair practice. For a basement foundation, a polyurethane foam is pumped beneath the basement to fill any voids and bring the floor up to level.
If the damage to the floor foundation is severe, then it may need to be replaced. This is done in conjunction with filling any voids that opened up beneath the foundation due to soil shifting or erosion.
Schedule a consultation with Straight Line Construction if you suspect that there are any problems with your basement foundation.
