During the construction or repair of a retaining wall, many DIY builders have a common question, do I need weep holes in a retaining wall? Many homeowners pay attention to the front face of the wall however, planning the back structure is also important. Water sitting still is one of the most common reasons for failure of a retaining wall. Weep holes are an inexpensive yet effective way to solve this issue.
This guide addresses your common question related to weep holes by defining what they are and describing their work and when a retaining wall needs them. The information about weep hole placement and spacing requirements is also explained.
What Are Weep Holes in Retaining Walls?
Weep holes are small holes made in the bottom of the retaining walls. The main function of weep holes is to allow water to escape outside the wall. When the rainwater or groundwater seeps into the soil, the weep hole lets the water pass to reduce the water pressure. Weep holes do not let the water evacuate a large amount of water at once, but they facilitate slow drainage over time. The weep holes are mostly designed in circular or square shape with the insertion of gravel or soil to prevent clogs.
How Weep Holes Work
Weep holes work by letting water to drain through the holes to prevent structural damage to the wall. When the water deposits inside the wall or after rain, the water can’t get past through the wall and accumulates on its other side. Weep holes in such situations helps by letting the water to exit through the holes. After the water is drained, the deposit of water is reduced and water pressure are decreased. Also, the gravel backfills and geofabric rolls are used behind the wall to let the water move freely to the holes and at the same time, to keep the dirt from clogging the holes.
When a Retaining Wall Needs Weep Holes
A retaining wall needs weep holes in following scenarios:
-
When the wall is more than 3-4 feet in height: Higher retaining walls have the capacity to hold back more soil and water. As water builds up, its pressure may damage the wall structure and strength. The weep holes act as an outlet for the pressure and thus contribute to the stability of the wall.
-
When the wall is built on a slope or hillside: Water generally tends to flow in the downward direction and gets collected behind the retaining walls erected on slopes. In case the weep holes are not built, the water can pass very rapidly and cause extensive damage to the wall.
-
Rainy and wet places: Rain or watering of garden plants forms a constant moisture behind the wall. Weep holes become the outlet for the water, thus preventing the water from soaking into the soil.
-
In areas with clay soil: Where soil is compact and composed of clay, as these soils trap more water, building high pressure.
-
For retaining walls made of concrete, stone, or brick: Water does not naturally drain out of these materials. Weep holes become a necessity to keep the water from being trapped which leads to cracks, shifting, or complete wall failure.
Weep Holes for Drainage and Prevent Water Pressure Buildup
Installing weep holes in retaining walls helps to prevent wall breakage by managing drainage to prevent water pressure buildup. As drains are managed properly, the hydrostatic pressure is released which secures the wall. If weep holes are not placed, drainage management can be challenging leading to building of cracks and collapse of wall.
Placing enough weep holes releases the pressures by improving the drainage. Proper drainage can also be helpful for surrounding plants and vegetation. The right amount of water drained means there is less chance of soil erosion and management of wet surfaces.
Common Weep Hole Placement and Spacing
Weep hole must be placed in the spot where it can pass without any disturbance. The most common location to place the weep hole and its appropriate spacing are explained below:
-
Wall Base: The base of the retaining wall is the most common place for installing weep holes. Weep holes in the base allow water to pass easily as water moves down due to gravity.
-
Above Grade: Weep holes are placed above the grade or ground level on the front area of retaining wall. It prevents debris and soil from blocking the opening and helps during inspections and maintenance work.
-
Cavity tray: In retaining walls, weep holes are also placed in the cavity tray or drainage layer as these trays collect water and pass it through the weep holes. Holes in the cavity tray minimise the risk of water trapping inside the wall structure.
-
Appropriate spacing requirements: Weep holes are placed by spacing evenly. Most weep holes are placed with a spacing of 3 to 6 feet based on the height of the wall, soil type, and amount of water accumulation. Even spacing ensures that the water is not stored or collected in the same area and is distributed evenly.
Conclusion
Weep holes in the retaining wall helps in releasing the hydrostatic pressure in the wall by evacuating excess water inside the world. As pressure are released and drainage systems are improved, the durability of a retaining wall increases. When walls are more than 3 to 4 feet high, built-in rainy area with uneven slope, and place with compact soil, weep holes in retaining walls are required. Visit Austrina Steels for more information related to retaining wall building procedures. We also provide high quality construction materials such as concrete sleepers, wall posts, and drainage accessories for high quality and durable construction.
