06 Jan Solid Foundation – How Rain Gutters Protect Your Home
Gutters are key players in the defensive line between your home’s foundation and the damaging effects of water. Properly installed and maintained gutters, along with proper underground drainage and waterproofing where necessary will protect your home from having a damp basement and potential settling and cracking of your home’s foundation. The potential damage to your foundation is serious and much more costly than installing and maintaining rain gutters and insuring the soil around your home’s foundation is properly drained.
Your Foundation Under Pressure
Depending on the location of your home the underground water table may be above the bottom of your basement. A soils engineer can determine if this is the case by digging test holes around your home. Even if the normal water table is below the floor of your basement, the soil will show signs that the underground water table may seasonally rise above the bottom of your basement. This is a serious situation that can potentially require major work to waterproof your foundation and provide drainage.
Even if your home’s foundation is not below the underground water table there may be water around your foundation. After your home’s foundation was excavated and the concrete floor and walls of your basement were poured, the space around the foundation was backfilled. Since the backfilled soil is less compact than the surrounding soil that was left undisturbed, surface water that is allowed to pool around your home is able to soak into the more porous soil. This improperly drained water seeps down and creates a false water table around your foundation.
Whether your basement extends below the normal underground water table or is being affected by a false water table created by poor drainage, the water surrounding your basement is under pressure. For every inch below the water table you go, pressure is being exerted by the overlying water. Just 6-feet below the water table the hydrostatic pressure reaches 2-1/2 pound per square inch. With so much pressure behind it, water can force its way into even the tiniest concrete fissures and cracks to enter your home.
Underground Drainage Systems
If your basement extends below the water table it is necessary to have a foundation drainage system. Foundation drainage systems and underground waterproofing installed during construction are far less expensive than those installed after the fact. An underground drainage system consists of a layer of coarse gravel below and around your foundation that lets underground water under pressure drain freely into the spaces between the gravel. Pipes with slots or holes are located in the gravel below the level of your basement floor to direct the drainage away from the house to either an external sump pump or an outflow below the level of the foundation. Underground drainage systems are typically used in conjunction with a waterproof foundation membrane.
Waterproofing and Damp Proofing
While waterproofing membranes are designed to defend your basement from groundwater intrusion, damp proofing simply fills small fissures in your basement floor and wall. Because small fissures in your concrete can draw moisture in similar to the way a wick can draw liquid, sealing them will prevent an occasional damp basement. Basement insulation will also help avoid condensation of moisture on your basement walls.
Waterproofing membranes are designed to protect basements from water intrusion in areas of high groundwater. It is preferable to install waterproof membranes on the outside of the basement during construction. In cases of serious moisture problems in existing basements waterproof membranes can be installed inside the basement along with a sheet drain.
If a high water table is not the problem but you are still experiencing water problems in your basement take a look at your landscaping. If you have paving stones or a concrete walk or driveway that have settled toward your house you may be adding hundreds of gallons of water to your problem. Paving stones can be re-leveled and concrete walks and driveways can be replaced with interlocking systems that allow blocks that settle to be raised and leveled to insure that they are draining properly.
The slope around your home’s foundation should have at least a 5-inch drop over 10-feet to insure that surface water can easily drain away without soaking in. Look for depressions where water collects and puddles form. If necessary you may need to bring in a load of topsoil to raise the sod around your house and insure proper drainage.
Rain gutters play a critical role in diverting the water collected from your roof. A one inch rain on a 1,000 square foot roof will produce 600 gallons of water. With heavy rains a common occurrence in New England, gutters are an important defense against water accumulating around your foundation.
Downspouts and Splash Blocks
The final link in your gutter system is often the most critical. Downspouts that are damaged, leaking or clogged with debris will quickly cause water to overflow the gutters or run down the side of your house. Improperly placed outflows and damaged or missing splash blocks can cause the same problem.
Downspouts should drain at least 5-feet from your home’s foundation wall. Insure that splash blocks are correctly leveled so that they direct water away from the house. Regularly inspect your downspouts to insure they are not damaged, disconnected, leaking or clogged.
The Foundation Team
Along with good surface water drainage provided by well-designed landscaping, properly installed and maintained rain gutters play an important role in protecting the foundation of your home from water intrusion and damage. In areas with a high underground water table it may also be necessary to have a waterproof barrier along with a foundation drainage system. For most in New England homes having a good surface water runoff system including properly installed and maintained rain gutters will be all you need to keep your basement dry and free of water damage.