The heavy rains that beset the Bay Area earlier this year caused properties across the region to experience flooding and water damage, which in many cases triggered foundation and drainage issues.
Mark Garrison, principal at MG Constructors & Engineers, said his company has been inundated with calls from homeowners with foundation problems.
Water damage caused by heavy rains can cause wood rot, corrosion, mold and mildew, and efflorescence – deposits of white salt on a foundation's surface, Garrison told members of the Silicon Valley Association of Realtors during a recent presentation on how to prevent and mitigate foundation damage.
The presentation was hosted by the association's Palo Alto and Menlo Park districts as part of the Realtor group's educational program to broaden members' understanding of crucial topics that directly impact homeowners, said Stacey Woods, the association's Palo Alto District chair.
Garrison called efforescence "the silent erosion of concrete foundations." Foundation settlement is another hidden threat, along with termites and leakage in the home's walls and floors, he said.
"Once water is in the crawl space or the foundation, it starts to wreak havoc," Garrison said. "You want the water away from the foundation. If it cannot be done, you want to at least control it."
Problems from persistent water
Sudarsan "Sonny" Vakul Srinivasan, the firm's engineering manager, said homeowners should observe the topography of their home, whether the structure is flat or sloped. Signs of exterior damage include pools of water next to the foundation, damp soil, wood rot and high humidity inside the crawl space.
Common causes of exterior drainage issues are downspouts draining next to the foundation, softscape or hardscape not sufficiently sloped away from the foundation, rain gutters filled with debris and improperly installed sprinkler systems. Water or high humidity in the crawl space can cause corrosion and mold and mildew, which can enter the living space, causing potential health hazards, Srinivasan said.
According to Garrison and Srinivasan, foundation settlement issues are common in the Bay Area due to soil composition and seismic activity in the region. The clay content of the region's soil does not drain and can increase liquification, a phenomenon when land behaves more like a liquid.
Poor drainage, or lack of it, are also major culprits of foundation cracks and movement. Garrison and Srinivasan suggest checking interior walls and exterior stucco for cracks. Large cracks, uneven floors, door and windows frames with large gaps or that are difficult to close are signs of a settlement issue, they said.
With proper maintenance, most foundation and drainage issues can be prevented or fixed before they get worse.
"A little bit of maintenance would go a long way," Srinivasan said.
Inspection of a property is one way to prevent surprises.
"Have a licensed professional evaluate the structural and drainage conditions of your home. These inspections provide a written report and the inspector's professional opinion on probable cost ranges for repair," Srinivasan said.
Professionals can provide a diagnosis of a residence to see if there is movement or cracking in the foundation as well as in other area's of a home, such as the walls, floors and ceilings. They also can examine retaining walls and drainage and review the degree of seismic risk mitigation for a foundation.
Garrison and Srinivasa provided the following list of preventive measures homeowners can undertake to protect their foundations:
• Remove debris and flush and clean rain gutters, downspouts and drain lines.
• Add extensions to downspouts to redirect water away from the foundation.
• Grade unpaved softscape areas around the home to slope a minimum 6 inches for the first 10 feet (that translates to a slope of 5%). Slope paved areas a minimum 2 1/2 inches for the first 10 feet, or install a subsurface system such as a French drain.
• Monitor cracks that surface in your home.
• Make sure interior and exterior drain and plumbing lines are functioning properly.
• Monitor the crawl space annually for signs of moisture, leaks, standing water, rot issues, corrosion and high humidity. You can use a hygrometer, which measures humidity and the amount of water vapor in air, to check humidity levels. The optimal humidity range should be below 40%. Anything over 60% humidity means serious issues.
• Employ a pest control program for foundations with crawl spaces.
Silicon Valley Association of Realtors (SILVAR) is a professional trade organization representing 5,000 Realtors and affiliate members engaged in the real estate business on the Peninsula and in the South Bay. SILVAR promotes the highest ethical standards of real estate practice, serves as an advocate for homeownership and homeowners, and represents the interests of property owners in Silicon Valley.
The term Realtor is a registered collective membership mark which identifies a real estate professional who is a member of the National Association of Realtors and who subscribes to its strict Code of Ethics.