What Does Expansive Soil Mean? Does It Impact Real Estate In Phoenix Arizona?

Can expansive soil have an impact on real estate in Arizona? The answer is yes because soil with “clay-like” tendencies, or expansive soil, can be found in pockets throughout the Phoenix Metro.

Keep in mind that builders are more aware of this than you and I and are able to prepare before construction begins. But it is still important that consumers are aware of these risks before going into perhaps the biggest purchase of their lives.

Ok, so before you start thinking you’re going to be swallowed up by the ground, let’s clear up a few details! Arizona soil contains properties that can be measured by its shrink/swell potential. That is, when the soil dries out it shrinks, and when it gets wet it expands or swells (expansive soil). This shrink/swell potential varies from one area to another depending on how much clay there is in the soil, and even what kind of clay it is!

So does this mean that expansive soil will eventually give me the open floor plan I have always wanted? Not exactly, although examples of damage caused by expansive soil can be found all around us. It can cause damage to building structures and foundations, or even the roads we drive on. It’s not unusual for evidence to appear in the form of cracks in the walls, doorways, driveways & garage floors, or even in patio decks! This is often referred to as “settling”. A potential solution, or reduction in the settling, can be addressed in the types of foundations used in new home construction. A post-tension slab is often used to help reduce the potential of settling.


If an area has a high shrink/swell potential, it would be considered hazardous to build within the soil, on top of the soil, and certainly when the soil is actually used in the building materials. Of course when the area has a lower potential for expansive soil, the hazard level decreases in accordance to the soil properties.


The U.S. Department of Agriculture has produced a map rating the levels of soil expansion in the Phoenix Metropolitan Area.


What can consumers do to protect themselves when buying real estate? Well, the Arizona Registrar Of Contractors says that if any crack is bigger than 3/16th of an inch wide, that it is considered to be unacceptable and requires the attention of a professional to determine what caused the crack. This can be negotiated during the inspection period of escrow.


Buyers should ask the seller to provide the “Commissioners Public Report” for the subdivision. If the seller is a new home builder, then the builder is responsible for providing the report to the buyer before the signing of any contracts. Ultimately, it is the responsibility of the consumer/homeowner to resolve any concerns by securing and independent assessment of the structural integrity of the building/home at hand.

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