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As home inspectors in the Phoenix area, one of the driest areas of the country, it would seem that grading and drainage problems would be of no concern. Actually, the opposite is the case. We are very concerned about the way rainwater will affect the property.

Several considerations make a home inspector’s job very difficult in the cities surrounding the normally dry Phoenix metro area. Let’s take a look at what a local home inspector might obsess about:

  1. The Phoenix area only receives about 8” of rainfall annually. Some parts of the country receive that amount in a weekend or in a single rain event. The problem is that much of the rain comes down rapidly during the monsoon season in the summer during the months of July and August. A single day of more than 1” of rainfall locally can be a big deal and a deluge of rainwater needs to be accounted for during the property design phase.
  2. Builders and homeowners can often get away with an amazing amount of disregard for grading and drainage locally. Our dry climate can take years for that one massive localized storm to reveal the drainage defects at a property. Just look around at how the homes here have flat sites with minimally elevated finish floors inside.
  3. The vast majority of local housing does not have gutters installed to control rainwater from the roof. Think of the roof as a huge area of collection for rainwater and roof designs often concentrate the roof runoff into zones around the perimeter of the structure. Most of the rest of the country routinely installs gutters with downspout leaders that extend 4 feet from the structure walls. Not here, we go without gutters and just see what happens.
  4. Final site grading is established by the builders during construction and has some portion of the property designed to retain a portion of the rainwater on site. The water is retained to allow for percolation into the soil on-site and avoid dumping all of the rainwater onto the streets.
  5. Normally, the design and final site grading is fine. These designs can have very little room for error and problems arise after the builder hands over the keys to the homeowner. Landscaping projects get installed by folks with little concern for maintaining the integrity of the site drainage design. Retention areas can get eliminated or removed, drainage paths can be altered and blockages to rainwater exit are often inadvertently created.
  6. Older properties may have additions installed that do not have the proper elevated finish floor height inside. Without the inside elevation being higher, the home is at risk of flooding.
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