3 Problem Foundation Types

A brick wall

There are 3 types of foundation types that we see that can be problematic. All 3 are all only found in pre-WWII era homes. Two are usually only found in homes built prior to the 1920s.

The foundation is important because it is responsible for distributing the weight of the home and its contents evenly across the soil or rock upon which the home is built. A stable foundation will prevent the home from sinking, settling, or shifting due to changes in the soil or natural disasters such as earthquakes or floods. It also helps to resist lateral forces, such as wind or seismic activity.  Hence identifying the foundation is a key part of a home inspection.

Let’s look at the 3 problem foundation types.

1- Brick Foundations

The use of bricks as a building material goes back thousands of years. Brick is a common building material throughout the United States. So it makes sense when early homes were built in Los Angeles, that brick was the material of choice for the foundation. However, unlike much of the rest of the country, Southern California is prone to Earthquakes. Builders quickly realized that brick does not hold up to seismic activity, and the use of brick for foundations was phased out in the early 1920s. However, thousands of homes were already built prior to this realization. Brick foundations are still common in Pasadena, Hancock Park, Downtown Los Angeles, and surrounding areas.

Another issue with brick foundations is that over time, the mortar that holds the brick together deteriorates over time. The mortar becomes powder-like and falls out, leaving the bricks loose. The are no known repairs for brick foundations. They can not be seismically retrofitted or bolted. Metal bars are often installed to help, but the primary purpose of such bars is only to hold the house together long enough to get out. The only permanent repair is a complete replacement.

Brick foundations should not be confused with brick facades, brick fireplaces, and other uses of brick in a home.

A brick foundation with mortar deterioration
A brick foundation with mortar deterioration in Hancock park

2 – River Rock Foundation

A river rock foundation is a type of foundation that uses large, uncut stones. The stones used in a river rock foundation are generally irregularly shaped and vary in size, but are typically between 8 and 10 inches in diameter. The stones are then cemented or mortared together. Like brick foundations, builders quickly realized these types of foundations do not hold up well to earthquakes. Like brick, they were phased out in the 1920s. River rock foundations are relatively rare compared to other types of foundations, but we do see them from time to time. Usually in Pasadena, Altadena, Sierra Madre, and surrounding areas. The only permanent repair is a complete replacement.

River Rock style foundation in Pasadena
River Rock style foundation in Pasadena
River Rock foundation
River Rock foundation in an 1895 home

3 – Low Rise Concrete Foundation with a cripple wall

After brick and river rock foundations were phased out, they were replaced with low-rise concrete foundations. The foundations are not as problematic as their predecessors, as they are repairable. However, they do have some issues of their own.

The main issue is because the concrete is low to the ground, the houses have what is known as cripple wall construction.  This is a short wall constructed of wood studs and is designed to fill the space between the top of the foundation and the bottom of the main floor of the house. Cripple walls do not hold up well to seismic activity and can be a weak point of a home’s construction. Insurance companies typically want to know if a house has unreinforced cripple walls.

Low rise foundation with cripple wall construction
Low-rise foundation with cripple wall construction

The good news is cripple walls can be retrofitted and reinforced.  A qualified foundation contractor can add plywood, along with seismic bolts or braces to bring a low-rise concrete foundation up to modern seismic standards.

A secondary issue with low-rise concrete foundations is the distance between the dirt and the wood is only a few inches. This makes the wood more suspectable to wood destroying organism that comes up through the ground.

Cripple wall that has been retrofitted to meet newer seismic standards

A cripple wall that has been retrofitted to meet newer seismic standardsThe low-rise concrete foundation is found on most homes built before 1940. After WWII, when the housebuilding boom hit Southern California, taller reinforced concrete foundations became the norm.

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