In every new home inspection, drainage problems are commonly identified. These unrectified drainage problems have the potential to affect the very foundation of the structure, which will result in not only inexpensive repairs but also affect the structural strength. Some of the common issues that cause drainage problems are –
- Grade sloping: This is usually a slope back towards the home that leads to damp or wet crawlspaces, foundation movement, cracking, or settlement. This can also cause the growth of mold or foundation movement.
- Moisture: This comes through the soil in the crawlspace where there is no proper venting.
- Cracks and offsets: These happen when root intrusion happens in the main sewer line.
- Structural, moisture, and concrete settlement issues: This happens due to poor drainage of gutters and downspouts. These are easily fixable issues that have the potential to cause major problems.
- Reversed splash pads: Eave troughs collect large amounts of water which is dispersed at the ground level and cause the majority of the issues.
The following pictures show various areas around the house that may experience an accumulation of moisture.
Areas around foundations are prone to settling and should be built back up to ensure that any water will flow away from the home. Here are a few basic recommendations on how to avoid moisture accumulation and protect the foundation:
- It is recommended to maintain or provide a positive slope away from the foundation with a space of one inch of fall per foot for the first five feet. Foundation dirt must be used in case soil has to be added around the foundation. Loam (a combination of sand, silt, and clay) can also be used for supporting foundations because it maintains water at a balanced rate.
- Maintain or provide splash blocks or downspout extenders at all gutter downspouts to discharge at least five feet from the foundation.
- Maintain or create a non-irrigated zone around the foundation for 5 feet, though 3 feet is the minimum requirement.
- Use a mesh fabric barrier adjacent to the foundation as it allows moisture in the soil to evaporate. Do not use plastic weed barriers.
- Downspout extensions are not very attractive and can be very obtrusive, however, they can carry drainage away from the home foundation.
To prevent or minimize structural movement
Firstly, it is important to prevent moisture accumulation in the foundation subsoils. Often the foundation issues will not be apparent, however, as the structure grows older the soil will expand and/or contract to cause the foundation to shift. These foundation issues can be repaired by installing piers around the foundation. Each pier will cost between $300 to $800 and they are placed every 6 to 10 feet around the perimeter of the foundation. The key to preventing or minimizing structural movement is to prevent moisture accumulation in the foundation subsoils. Generally, water accumulation happens in low spot/flat/improper/low/negatively sloped drainage area towards the house where water ponds can form and cause the foundation to shift. These are all building code violations.
RSH recommends that all low spot/flat/improper/low/negatively sloped drainage areas should be provided a positive slope (away from the foundation) of 1-inch of drop every foot for the first five feet if possible. The building code requires a minimum drainage slope of a 6-inch drop-in 10-feet away from the foundation. Do not let water pool/pond around and within 5-feet of the foundation
Mathew Joseph, P.E. with RSH Engineering, Inc. has performed thousands of inspections in the DFW areas since 1994. One of the most common issues that Mathew finds in a home is poor drainage slope around the foundation.
Call Mathew with any of your questions regarding your home and he can provide free consulting for up to 5 minutes. (972)523-5746. www.rshengineering.com.