December, 2008

Inspection News and Views from the American Society of Home Inspectors

Foundation Problems and Identification


A preview of this 2009 IW session

During our ASHI Standards of Practice home inspections, we’re required to inspect the structural components of a home, including the foundation. We look for visible defects in the foundation and for signs of deterioration. While I’ll be covering this topic in-depth at InspectionWorld Orlando, I’d like to share some basic steps that I find helpful for inspecting most types of residential foundations.

Begin with the soil

Soil is the first factor to consider when inspecting a foundation. Since the footings of a foundation depend on competent soil, I look for any indication of soil failure near the foundation or on the property. It could be actual landslides, creep movement or, most commonly, poor drainage. Water is, in fact, the primary cause for the failure of a house’s components from the foundation to the roof.

Regardless of the type of foundation system, and there are many, we must be observant of drainage. Seldom is a foundation designed to compensate for potential site flooding or poorly bearing soils. Most residential foundations depend on moisture being removed from the site by natural drainage and/or footing/site drains. If this is not being done, I look for signs of damage, and I recommend the drainage be corrected.

Look for movement-prevention components

After noting any visible signs of soil failure or poor drainage, I look for improperly installed or lack of components that help prevent movement in the event of outside forces such as seismic events and/or high winds. Foundation bolts or clips help prevent rotation of the house off the foundation. Holdowns help prevent uplift of the building or portions thereof. Lateral bracing (aka shearwalls) helps prevent wracking of walls and catastrophic failure during an event. Most of the time, I find all or some of these missing in older homes. I recommend upgrading for increased performance.  Of course, it’s up to my clients to decide whether or not they can afford or are willing to pay for the upgrades.

Photo: Although buttresses have been added to this structural retaining wall in an attempt to strengthen it, as it continues to fail the soil supporting the building footings will be compromised.  Photo by M. Casey.

 Illustration reprinted with permission of Carson Dunlop & Associates, Ltd.

Note indicators of excessive movement

As I inspect the house inside and out, I am cognizant of any indicators of possible excessive movement. I consider the age of the house, type of construction and pattern of the indicators. For instance, a single hairline crack in the foundation may not cause me to recommend an evaluation by an engineer. On the other hand, multiple cracks and/or other conditions that fit a pattern may be enough for me to recommend further review.

And more

Other items I consider include separate structures that may affect the home, the most common being structural retaining walls. These are walls that retain soil
affected by the cone of compression of the house footings. In other words, if this retaining wall failed, the soil supporting the house footings would be compromised. When I see walls that are failing, I recommend replacement. When I do, I’m usually asked how long the wall will last. My usual response: “I don’t know. However, it is failing and could completely fall at any time. An engineer might give you an estimate of when, but inevitably the wall will need replacement.”  
These walls are typically expensive to replace and no one wants to throw $30,000 into a hole. But sooner or later, someone is going to have to do so.

Of course, some people go to great lengths to conceal evidence of major foundation failure; we’ll view a couple of these case studies at InspectionWorld!