Question: We live in an older home on Santa Barbara’s Mesa that was built on a very flat lot and is on a raised foundation.
During wet winters like we are having now, the crawl space under our home, which is lower than the yard, fills with rainwater and sometimes will take weeks before it dries out even though there are vents in the foundation wall allowing air circulation.
I am concerned that this standing water is bad for the house, but I have no idea how to keep the water from accumulating or how to dry it out quickly.
Any ideas would be appreciated!
Your Handyman: Once again despite expert predictions of a very dry winter caused by warm ocean temperatures (La Niña) we instead have a very wet winter.
There are many Santa Barbara-area neighborhoods that are mostly flat without good natural surface drainage. When these areas were developed, the houses were not raised up but were built at the natural grade of the land.
In some of these areas, the floor level of the house is within an inch or two of being level with the street and water in a heavy downpour has nowhere to drain to and can flood the garage, the crawl space or penetrate under the cement slab.
Standing water in the crawl space under a house can cause all sorts of problems with the humidity causing rust on piping and electrical components, dry rot to wood framing and sometimes mold.
So, what can be done?
Every house needs rain gutters to move rainwater away from the home and especially away from a below-grade crawl space under the structure.
The gutters should be the continuous aluminum style that is shaped from a roll of aluminum on the job site, which minimizes seams that can be prone to leaking.
Ideally, the downspouts should not be spaced more than 30 feet apart so the gutters don’t overflow during heavy rain. Lengths of flexible tubing can be added to the bottom of the downspouts to further move rainwater away from the house.
Sump pumps are electric water pumps that are submersible and are activated by a float valve when the water level in the sump rises to a certain level. The water is then pumped out from under the house via a PVC pipe, ideally to the gutter on the street or to an area that will naturally drain away from the house.
Do not drain into the sewer line, which is illegal and can cause sewage spills from the overloading of the sewer systems during a storm.
Sump pumps are mostly used in basements where the concrete floor is sloped to the sump to facilitate drainage, but they also can be used in a dirt crawl space if there is slope.
The sump pump needs to be plugged into a GFCI-protected outlet to prevent any sort of electrical shock and should have the style of float valve that rides vertically on a shaft, which is most reliable.
French drains, if correctly planned and installed, can channel water away from a house, provided there is adequate slope on the property. I have known of numerous cases in which a homeowner spent considerable sums of money on a drainage system that was not correctly planned and was unhappy with the results.
A golden rule of plumbing is that a drainage line needs a minimum slope of a quarter-inch per running foot; if the slope is less, it will be considerably less effective.
A French drain is usually a 4-inch diameter white plastic pipe with holes running at about the center line. The pipe is buried at the location where water is entering the house and then flows downslope to a location where it finds daylight and drains.
The starting point needs to be lower than the crawl space area in order for water to flow into the drainpipe instead of seeping under the house.
