The foundation of the home is the most important part of the structure of the home. Having a structurally strong home starts with having a strong foundation and protecting that foundation is paramount.
If your home is in a low area, a flood zone or has one or more areas where the landscaping is directing water toward the home or at least not directing the water away from the home, then landscaping is very important to the structural integrity of the home.
Many factors contribute to a good foundation which would be too exhaustive for a simple blog, however one of the most common issues that homeowners face, is the effect that moisture can have on the foundation of the home. Over the life of a home, few things cause damage the way water does. Water can go un-noticed until after it has caused damage to the home.
Some common issues to be aware of.
Backfill settles. "Backfill" is the dirt that is pushed back up against the foundation after the building process. Even if the dirt was adequately tapered away from the home initially, over time that dirt can settle and allow water to flow against or sit at the foundation and over time can compromise soil integrity. If the back fill has settled additional back fill may be the answer as long as proper clearance is provided between the back fill and the wood components and siding of the home. A landscaping contractor should be able to help make that assessment.
Negative or low grading toward the home. In other words, the landscaping is sloped toward the home which is channeling the water toward the home or at least the grading is not adequately moving the water away from the foundation of the home. If water is sitting at the foundation or is rushing toward the foundation, the soil integrity can be compromised. In a crawlspace home, moisture may also be able to penetrate the foundation wall and cause elevated moisture in the crawlspace which in turn can affect the integrity of framing material as well as promote microbial growth.
Proper landscaping is key. Proper landscaping helps move water away from the structure and thereby help prevent moisture intrusion and damage. The following are potential improvements that should be discussed with your landscaping contractor.
Properly conditioned and graded backfill. Where possible this may be the most economical option. A proper mixture of soil and clay that is properly sloped to move water from rain or gutter downspouts away from the home. In general, the backfill should slope 6 inches in the first 10 feet. Gutter downspouts should discharge 6 feet away from the foundation. Another water source that is not given much thought is the discharge from the AC which like downspouts should discharge at least 6 feet from the foundation. Air conditioning produces a considerable amount of water during hot summer months, particularly in hot, humid climates.
French Drains. When backfill is not an option because doing could compromise framing, siding or cause other problems, then French Drains may be a viable option. An exterior French drain is a trench 6 inches to a few feet in diameter that is dug along a declined slope on a property. It is then covered over with gravel to prevent excess mud and debris from entering the trench, and to prevent soil erosion on the inside. Perforated piping, called weeping tile, may be laid underneath the gravel to accelerate the movement of water through the trench. Gutter downspouts from a home’s roof may empty directly into a French drain system to alleviate flooding due to excess rainfall.
Swales are shallow ditches used to capture and divert rainwater. Unlike French drains, they do not contain piping to carry the diverted water. They are typically located along the property's boundary following a natural grade, as recommended by the U.S. Environmental Protection Agency (EPA) and rely primarily on existing topography for their required natural slope. Swales are commonly vegetated to promote the filtering of water and to encourage it to soak slowly back into the ground. According to the EPA, swales are impractical in areas that are commonly wet or have poorly draining soil and may erode during peak flows.
As always, a qualified professional contractor, in this case a landscaping contractor, should be consulted prior to taking on a substantial project. You want to make sure you have the proper plan in place so that you are improving the property and that you do not inadvertently cause damage to your property or to your neighbor's property, such as directing water from one area only to create an issue in another. This is especially true of your neighbor's property as that could cause a poor relationship or worse, legal unpleasantries.