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In the Phoenix area, it is rare to see gutters installed along the roof perimeters. In other parts of the country, roof gutters are used extensively for controlling moisture around the building. Why not in Phoenix?

seamless gutters on a home

The easy answer is: because we only get about 7 or 8 inches of rain per year. Low volume of rainfall is the most likely reason for the lack of moisture control around Phoenix area buildings. It is important to keep in mind, however, that the local rain event intensity can be extremely high. During summer monsoon storms a single rain event can result in flooding of the building interior. Home flooding in the Anthem area this year highlights the need for preventative measures. To reduce the risk of interior flooding and other problems, we would be better off copying the building techniques of other more damp locations.

Three common ways to protect the building from moisture problems are to:

  1. Install gutters at the roof line with downspouts directed away from the building.
  2. Slope the soil adjacent to the building away from the foundation.
  3. Avoid installing irrigation system bubblers within 3 feet of the structure.

Ideally, your finished floor inside the building should be adequately elevated above the surrounding grade. In some areas of the valley the soil consistency presents a problem. Areas of high caliche content (a hardened deposit of calcium carbonate) will prevent surface water from penetrating into the soil. This condition is known as poor percolation rate. If you suspect that you have this problems a civil engineer can design prevention measures to protect your property from flooding.

Moisture control around the building is also important for the prevention of termite infestation. As termite inspectors, we often report “negative grade” conditions around the structure which is basically an improper slope of the soil toward the structure. We also see foundation damage at the perimeter of the structure from excessive moisture combined with sulfates in the soil (see below).

sulphate spalling damage to concrete

Problems with site grading and drainage often begin right after construction. The final grade of the property is established by the builder and should include slope away from the structure as well as some provision for on-site retention of a portion of the rainwater that falls onto the property. The site drainage design is very often ruined by landscaping projects that make the property look better but perform worse in a storm.

Moisture control around structures is critical even in the desert environment. Take some time to analyze your own property to be sure you have proper protection. If you have any questions or concerns please give us a call.

Advantage Inspection Service provides professional home inspection services for homeowners and potential home buyers throughout the Phoenix metro area.

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