Foundations Crack on
Expansive Soil
Fundation problems increase with drought and rain. These articles help explain why.
[UPDATE: Working with the Texas Society of
Professional Engineers, HOT helped pass a law requiring new homes built on expansive soil to have engineered
foundations.]
More homes suffering from foundation problems
By KATE MURPHY, The New York Times, 03/06/10, http://seattletimes.nwsource.com/html/realestate/2011259620_realfoundations07.html
Steven Derse, the owner of a corporate travel business in Nashville, Tenn., cannot feel his house move, but he
can hear it.
"It's an eerie creaking sound," he said, and it echoes throughout his two-story Georgian-style
house.
It started two years ago when a severe drought contracted the soil
beneath the foundation, which caused it to crack and sink, pulling the house down with it.
The noise has continued intermittently, becoming more insistent last year when flooding pushed the already
compromised foundation and house back upward.
This seesawing effect was noisy and expensive. Derse has spent more than $10,000 to install subterranean piers
to stabilize his foundation, and he expects he will have to install more to prevent further cracking and crumbling.
[HOT: The "seesawing" effect, or Dome heave and Edge heave, is
described in our Soil Issues paper.]
"You lose your sense of security," he said. "You love your home and then it literally turns on
you."
His is not the only house buffeted by shifting soil. Extreme weather
possibly linked to climate change, as well as construction on less-stable ground, has provoked unprecedented
foundation failures in houses nationwide.
Foundation-repair companies report a doubling and tripling of their business in the last two decades with no
letup even during the recession.
"We've seen a tremendous influx of pretty severe cases due to either drought or too much rain," said
Dan Jaggers, vice president of technical services at Olshan Foundation Repair, which has offices in the South,
Midwest and Great Plains.
"People call panicked because they've got gaping cracks in their walls, tile breaking, grout popping and
they don't know what to do."
Other telltale signs of foundation failure include doors and windows that will not close, chimneys or porches
separating from the house and bowing basement walls.
After a particularly dry summer followed by deluges in the fall, Psonya Wilson, a lawyer in Brandon, Miss.,
noticed light streaming in where the wall had separated from the baseboard in the bedroom of her 5-year-old
son.
"I could stick my finger through it," she said. "I couldn't believe it. The whole back part of the
house had sunk about 6 inches."
To stop further collapse, not to mention to control the draft, she is having several stabilization piers
installed to shore up the foundation of her two-story garden style house; it will cost more than $5,000.
Clay soils, like those beneath the houses of Derse and Wilson, shrink
during droughts and swell during floods, causing structures to bob. [HOT: These clay soils, which shrink and crack when dry, can swell 30% with wet
and exert up to 15,000 pounds per square foot of pressure on foundations and retaining walls.]
And because sandier soil loses its adhesive properties in dry conditions, it pulls away from foundations.
Heavy rains cause it to shift or just collapse beneath structures. With both kinds of soil, such sinking, called
subsidence, usually happens gradually, said Randall Orndorff, a geologist with the U.S. Geologic Survey.
But, he said, "swinging from very wet to extremely dry weather like we've been seeing lately in many parts
of the country may be accelerating the effect." [HOT: It seems that
newer homes have more foundation problems as builders cut corners to reduce costs. It also seems
that most of the problems are related to post-tensioned concrete slab foundations.]
Subsidence is not covered by most homeowners' insurance policies
in the United States, unlike in Britain, where the increasing number of homeowners' claims due to foundation
failure prompted the Charter Insurance Institute, an industry-trade group, to issue a dire warning about the
financial drain in its 2009 report, "Coping with Climate Change: Risks and Opportunities for
Insurers."
"The question we need to ask is, are we building to cope with the enhanced weather events related to climate
change," said Brenda Ekwurzel, a climate scientist with the Union of Concerned Scientists, a nonprofit group
advocating science-based solutions to environmental and health issues. [HOT:
This has far more to do with shoddy construction and the lack of regulatory oversight than climate
change.]
"It's obvious that we need to look at changing building codes worldwide to deal with this."
Compounding the problem is that, during the recent housing boom in the United States, houses were built in areas
where the soil was particularly prone to shift.
"If you think about it, the best ground in cities is usually taken early on, so the builders and developers
have often been expanding into less-desirable areas, and in their rush to make money, may not have designed
structures to deal with it," said David Lourie, a geotechnical engineer in New Orleans.
Fixing a failed foundation usually involves hiring a foundation-repair company to install cement or steel piers
around the perimeter of the house's slab or near its existing piers if it is a pier-and-beam foundation.
Once in place, hydraulic jacks lift and level the house and transfer its weight to the new supports.
The cost depends on the severity of the problem but generally runs about $1,000 to $2,000 per pier, which should
include a lifetime transferable warranty.
"It's amazing to watch your house get jacked up like that," said Miguel Rivera, a designer of heating
and air-conditioning systems, who had to pay $13,000 to have his 60-year-old house in West Orange, N.J., shored up
in January.
"It's just immediate. You're like, 'Whoa, up it goes.' "
His dining room began separating from the rest of his house about five years ago after repeated heavy rains
shifted the earth beneath it.
The problem was made worse when he removed a nearby tree, which was probably siphoning off excess water and
providing structure to the soil beneath his house.
"It often happens that you upset the moisture and structural balance when you knock down or tear out
trees," said Lourie, the geotechnical engineer, adding that planting trees too close to the house can be
harmful. "Plant them at least half their mature height away from the house."
Landscaping should, as a rule, be installed so that water slopes away from the house and gutters should
discharge at least 5 feet from the house to avoid oversaturating the soil.
During droughts, experts recommend placing soaker hoses around the perimeter of the house and turning them on 30
minutes a day.
"The idea is to maintain a constant amount of moisture in the soil," said Tom Witherspoon, a foundation
engineer in Dallas. "If you can do that, your house will never move." [HOT:
But homes built close to each other must contend with drainage and rain gutter downspouts from neighboring homes,
as well as the fact that neighbors don't water their lawns the same way on each side.]
VIDEO: Drought wreaks havoc on Central Texas foundations
The lack of rain is hitting home -- foundation problems are on the rise as soil moisture continues to
drop.
By George Kanuck, KVUE News, 07/24/2009
Source:
http://www.kvue.com/news/local/stories/072409kvue_foundation_drought-cb.71f3dd48.html
 Douglas Plauche, the owner of Douglas Foundation Repair, walked KVUE News
through a Taylor home ravaged by the drought. He says cracks in your
sheet rock and doors that stick or won't stay open are the some of the first warning signs of foundation
trouble. Plauche says his business typically doubles during droughts.
What causes the problem is a lack of moisture in the soil. As the soil dries out, it shrinks, which causes a house
to settle unevenly. Uneven settling will buckle the foundation, and it's not just the lack of rain -- trees are a
huge part of the problem.
"The slab maintains a hydration that the exterior doesn't have," said Plauche. "The tree learns that,
sends massive amounts of roots under there, sucks that moisture out to survive. And that drops that house faster
than anything."
But there is a cost effective way to solve the problem. By installing a soaker hose, you can evenly hydrate the
soil around your foundation. Plauche recommends putting the soaker hose on a timer.
"Watering your foundation requires a consistent plan of action. You cannot do it by randomly thinking 'I should
water my foundation," he said.
Plauche says you should run your soaker hose on a timer as much as 15 to 30 minutes, twice a day when conditions
are this dry. It may mean a higher water bill, but it's pennies compared to the cost of major
damage.
[HOT: Watering with a soaker hose next to the foundation, as shown in the video, is
not an especially good idea since it creates major differences between wet and dry spots. Better would be
normal lawn irrigation from an automated sprinkler system. If your lawn and plants look OK during a drought,
your foundation is probably OK too. The problem with foundation watering is that even structural engineers at
Texas A&M Construction Science Department or US Department of Agriculture don’t agree on how to do
it.
Many factors include how expansive and deep the soil is, the slope of the lot, the depth of the water
table, the trees & vegetation, and nearby neighbors. Soil Issues and Residential Construction in Texas is an easy to read white
paper explaining the effects of expansive soil and showing which regions are most at risk. Our site also has
several news articles on foundation failures, and you can search by keyword.]
"$4,000 is probably low end. Average is probably $7,000. High end can be over $18,000," he
said.
The City of Austin and several other cities have outdoor water restrictions in effect. Residents are urged to check
their watering rules and schedule.
The results are immediate. Douglas says you could see a change in your home in about a month.
He adds that cracks are common -- and not worrisome -- in newer homes as the house settles. It's when cracks start
forming several years later that could be a sign of major problems, and that's when you'll want to call an
expert.
[HOT: Minor problems can correct themselves with proper watering or when weather
conditions change, but the major problems shown in this video are primarily the result of exemptions to the
Engineering Practices Act. Contractors have not been held accountable and instead have been allowed to cut
corners and avoid the expense of engineering the foundation. The good news is that HOT worked with the Texas
Society of Professional Engineers on a new law that removes engineering exemptions that previously applied to
new home construction. From now on, homes built on expansive soil must have properly engineered
foundations.]
READER
COMMENTS:
pdikemanof
cedarcreek wrote:
I wonder why the buillders don't mention this? I have a 5 year old Centex Home. They were recently sold to Pulte
and they never mentioned anything to us about watering a slab.
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