Diverting Water from Foundation
How to Divert Water Away from Foundations with Retaining Walls
Learn how retaining walls divert water away from foundations to control erosion, runoff and silt accumulation. Reroute the neighbor’s runoff rivers. Slow down silt accumulation. Keep water from washing away landscaping dirt. Before building a retaining wall, understand the basics in their proper design.
Why Divert Water Away from Foundations
Soil Erosion / Sediment Accumulation
Any home owner with a house on a slope has watched storm runoff tumbling down around the house. Either stuff gets washed away or washed up against the house. Retaining walls help prevent runoff from eroding away yards and from sediment accumulating up against homes. Both erosion and washed up soil are foundation maintenance nightmares.
Foundation maintenance is all about keeping soil moisture levels even. That starts with sloping soil away from the foundation so water can drain away evenly.
Soil erosion washes away that slope, thus allowing water to pool around the house. Silt accumulation goes the other direction, allowing soil build up. This directs water in uneven channels around and under the foundation. Both create uneven moisture levels to develop around and under the foundation with the end result being foundation heaving, shifting and cracking.
Retaining walls help divert water away from foundations so that dirt is neither wash away nor pushed up against your home.
It is raining again and you are watching water streaming up against your back door or pouring under and into your home. Retaining walls can help divert water away from foundations during flooding. Often they are just a part of a water flow management solution. Combined with proper guttering, French drains and foundation swales, most water can be diverted away from the foundation and home.
Divert Water Away from Foundations – Preparation
Before starting on your project, watch how the water moves across where you want to install the retaining wall. Figure out what direction you want the water to move. Make sure solution does not create new problems. Decide on the best possible path water can be redirected. Saving your home’s foundation to wash out your driveway would definitely be more than mildly disappointing.
Make sure retaining walls stand up to pressure so they don’t buckle and collapse. Avoid retaining wall failure by ensuring soil stabilization and proper wall drainage. Clay soils retain water for a long time, exerting pressure against the wall. On the other hand sandy soils and small rocks or gravel allow water to drain easily. Make sure to get the proper mix behind the wall.
Retaining Wall Tips
Remember the purpose of the retaining wall is holding water back and diverting it away from the foundation. Even with properly stabilized soil, when rain is pouring down, water pressure temporarily builds behind the wall. Build drainage into the wall. Perforated piles installed behind the wall along with weep holes are an important way to control both the water flow and pressure build up
Construct walls for strength. Height, base width and tilted help determine the load the wall can bear. Higher walls and wider bases tend to be stronger. Walls that tilt back toward the slope also tend to withhold under stormwater pressure.
Types of Retaining Walls
When looking to divert water from the foundation with retaining walls, there are a number of types of several types to consider. Each adds a different look to your landscaping.
Gravity Retaining Wall
Gravity walls use their weight to stand up to the pressure of the soil it is holding back. They are constructed with stone, concrete or any heavy building material. It starts wider at the base and gradually recess in size as you get to the top of the wall but it may lean back towards the soil to increase stability.
Wood Wall / Anchored Wall
Wood wall or anchored retaining walls utilized concrete anchored support beams. The support beams need to be at least 40% underground in the cement base. Space support beams a minimum of 1 ft apart. For the wall, layer the wood horizontally in front of the support beams.
Cantilevered Retaining Wall
Cantilevered retaining walls are concrete similar in design to a Gravity Retaining wall with the major exception being it includes a concrete foundation. The concrete foundation base extends into the soil. Cantilevered walls require less building material to build than Gravity walls. Make sure that the base is at the frost line of the area you live in.
Sheet Pile Retaining Wall
Use sheet pile retaining walls in confined spaces that have looser soft soils. Usually made of steel or wood, plank walls go 2/3 into the ground leaving the top 1/3 exposed. Cables anchor walls to another plank that is driven into the ground at a set distance back from the wall.
Things to Remember
Before starting on your Retaining wall to divert water from the foundation, be sure to:
- Check your local zoning, permit requirements and/or ordinances
- Check with your Homeowner’s Association about potential covenants
- Develop a landscaping plan for after the wall is built
Frederick Marshall is the CEO of Advanced Foundation Repair, LLC, a foundation repair company specializing in home repairs from the foundation up including foundation repair, foundation drainage, exterior foundation waterproofing, foundation irrigation, and plumbing services. Advanced Foundation Repair has specialized in foundation repair needs of Texas homeowners for over 100 years. Connect with him on Google+.