cracks

Lets settle this crack issue

One thing that comes up often during home inspections is foundation cracks.

Most people have heard about someone who had a terrible foundation crack that cost them thousands! Unfortunately, these stories can be true but let’s unpack the term foundation and take a better look at those dreaded cracks.

The term foundation refers to the structure that transfers the weight/load of the house to the soil.

The most conventional modern foundation in Salem, Oregon is a poured concrete continuous perimeter foundation. This type of foundation is made with poured concrete (obviously) and will have a crawlspace most of the time but can have a basement. We don’t see to many basements in this part of Oregon due to the lack of frost. In colder climates the depth of the footing must be below the frost depth or how deep the ground freezes, to prevent heaving. That is why you see basements in cold climate areas. This perimeter foundation can also be made with concrete/masonry block (this was popular in the 1960’s in the Salem area).

Foundations can also be slabs. The entire footprint of the house is a concrete slab with a thicker section around the perimeter to act as a footing. We don’t see very many slab foundations in the Salem, Oregon area. Continuous perimeter foundations are more common because they are less expensive (they use less concrete than a slab) and a crawlspace is a great area to run pipes and wires after the house is built.

On very old houses, 100 years+, we can still see post and beam houses. Some real estate pros will state that because the house does not have a “continuous perimeter” foundation that these houses don’t have a foundation. This is not true as the definition of foundation is the transfer of weight to the soil. Although unconventional by today’s standards these houses are still transferring the weight/load of the house to the soil. These posts and beams can be huge timbers 16″x16″x30′. They typically have issues with wood destroying insects but that is more about moisture management issues than anything else.

Now that we have a pretty good idea about foundations and what they are let’s look at the cracks that can occur in continuous perimeter foundations.

The most common types of cracks are small (less than 1/4″ and mostly vertical). This type of cracks indicates shrinkage. Concrete cures or hardens as a chemical reaction and I have heard people say that it hardens for 100 years! As it is hardening it is also shrinking. As it shrinks is needs to take up less space and it cracks. These cracks do not affect the ability of the concrete to transfer load to the soil and are very normal.

small, vertical= shrinkage= not a concern

Now we can start looking at cracks that are of concern. In general, any crack that is bigger than 1/4″ should be further investigated, but the shapes of cracks can also indicate the type of movement.

Diagonal cracks. Diagonal cracks are an indicator of movement. Typically, there is a soil/water issue that is affecting the ability of the soil to carry the weight of the house.

“V” shaped cracks are also movement indicators.

Horizontal cracks are another type of crack to watch for.

That covers the most common types of cracks that we see during inspections. As always, if you have any questions about a crack in your life feel free to shoot me a call or email!

Foundations; Which type of cracks are ok?

Foundation cracks are typically something that home inspectors look for around the perimeter inside and out. Foundations in Marion and Polk counties are usually a poured concrete or possibly concrete block type foundation.

Concrete does two things, it gets hard and it cracks. Small, less than an eighth inch, vertical cracks are typically indicators of shrinkage and are a normal part of the concrete curing process. The cracks that are potentially structural in nature falling in a few categories.
1. Diagonal cracks: these cracks typically occur near corners and indicate that the corner has settled. This happens either with moving down, or uplifting moving up. Diagonal cracks typically occur in pairs. One on either side of the corner.Cracks in a foundation in a old home in Salem Oregon.

 

 

2. Horizontal cracks: these cracks typically indicate pressures against the foundation wall from soils. Either in properly backfilled soils or soils that have unusual amounts of moisture creating excessive pressures.

 

 

3. Cracks with displacement: displacement indicates movement on either side of the crack. One side of the foundation has moved forward or back more than the other side. Displacement can occur with any of these types of cracks and is always an indicator of structural movement.

 

 

4. Cracks that are wider than one quarter inch: this indication can also occur with any of the previous mentioned cracks. Cracks that are larger than one quarter inch may indicate a significant amount of structural movement and repairs may be needed. When cracks of this size are noted standard operating procedure for most good home inspectors is to recommend a structural engineer further evaluate.Large foundation crack noted during a home inspection on a concrete foundation in a North East Salem, Oregon home.

 

 

Those are the styles of foundation cracks to look for. If any of the above four are noted it may be time for further evaluation. Home inspectors are always a good non biased source for structural evaluations.