Watch the video on Capillary Breaks.
Preventing water from getting into the home should be a priority for all builders today. Water intrusion can leave the builder liable for both the initial damage to the home's structure through rot, and also to health and safety of the homeowners if mold gets a foothold in the house. While the most obvious source of water damage may be from precipitation like rain, water can also defy gravity and invade the home through the foundation using capillary action.
Capillary action is the technical term used to describe how water "wicks" or moves up from the ground and is absorbed into the foundation. This action occurs because water is sticky—water molecules stick to each other and to other substances. Place a sponge on a wet countertop and the water will soak upward, saturating the sponge. Likewise, trees use capillary action to pull water from the soil and up their trunks.
Finding a way to stop this natural flow of water is important if the builder hopes to deliver a home that's dry, safe, and durable. The best practice in protecting the home from water moving up into the foundation is the use of capillary breaks.
A capillary break is created using either an elastomeric asphalt coating or a polyethylene sheet. There are several ways to properly create this barrier, and multiple locations in the home's foundation where it should be employed.
Here are a few pointers:
- Place a capillary break between the footing and the foundation wall. This can be done by spraying the footing with an elastomeric asphalt coating or by covering the footings with a polyethylene sheet.
- For slab-on-grade construction or a basement slab, lay a sheet of polyethylene under the slab. Be sure to overlap the edges by at least 6 inches, and tape the joints with construction tape.
- On the vertical face of the foundation (exterior walls) be sure to clean the surface and fill any cracks or gaps larger than 1/8" wide. Spray on a coat of elastomeric asphalt starting 4" from the ground and completely covering the surface to the top.
- When building a brick wall, be sure to create a capillary break where the foundation ends and the wall begins. Either an elastomeric asphalt coating or polyethylene sheet should be put down before the first course of bricks is set.
Taking the time and effort to create capillary breaks in the foundation can be a thankless task. Homeowners may never realize the extra steps a builder takes to help ensure that their home is safe and dry. But the benefit to the builder can mean less liability risk and a well-deserved reputation for quality.
For more information on foundation construction visit the Building America website or click here for more information.
| 
