In order to provide proper drainage, at least 12 inches of granular backfill (gravel or a similar aggregate) should be installed directly behind the wall.
3/4'' clear gravel is typically used for drainage BEHIND the wall. It's excellent for this purpose.
For proper drainage you need at least 300 mm of gravel or similar material directly behind the wall. If you're planning on landscaping behind the wall, allow for at least 150 mm of topsoil above the gravel.
Absolutely! Even a 2-foot retaining wall needs an effective drainage system. Without it, water can build up behind the wall, leading to pressure that might cause the wall to lean or even collapse. All walls need systems to manage water effectively, preventing damage over time.
In order to provide proper drainage, at least 12 inches of granular backfill (gravel or a similar aggregate) should be installed directly behind the wall. Compacted native soil can be used to backfill the rest of the space behind the wall.
Hydrostatic Pressure and Wall Failure
When water isn't properly drained, it can accumulate behind the wall, exerting pressure on the structure. This pressure can prompt the wall to shift, crack, or even collapse. To avert such failures, it's crucial to have adequate drainage behind the retaining wall.
A drainage pipe might be needed if: The retaining wall is at least four feet high or taller. Clay or other poor draining soils are behind the wall.
Soil saturation is the most common external factor that causes retaining wall failure, but there are many ways to prevent it.
Rules of thumb commonly used by designers to establish the geometry of the wall include (refer to diagram): Base width = 1/2 to 1/3 of the height of the wall. Base thickness = 1/8 of the height of the wall but not less than 12 inches. Stem thickness = 6 inches + ¼ inch for each foot of wall height.
Install (or Add) Weep Holes
Weep holes are small, evenly-spaced holes along the bottom section of your wall. They protect the structural integrity by allowing underground water to seep through, preventing pressure build-up. Every retaining wall should have them.
One major thing to avoid when building your retaining wall is lining the back of your wall with plastic sheeting as this will surely result in the pooling of water behind the wall.
Sometimes retaining walls are designed as cantilevers. These typically include reinforcement and rely on the combined strength of the concrete and reinforcement to resist bending at the base of the wall. In that case, plan on waiting seven days before placing the full depth of backfill.
We recommend a 10-20mm clean, free drainage aggregate such as river stones or coarse crushed rock. It is imperative that the material is free from any soil, sand or other fines to ensure that water can flow freely through the drainage area and away from the back of the wall.
It's perfect for taking care of mushy lawns or preventing water from building up behind a retaining wall, which could cause it to collapse. It's also common around house foundations, where it can help stanch basement flooding, mold, and mildew.
Installing an ag pipe behind a retaining wall is essential for proper drainage and long-term stability.
Discover how the right retaining wall can reduce soil erosion, improve water drainage, and transform your property. Depending on the material, soil, and groundwater, a permanent retaining wall can last anywhere from 25 to 100 years.
Foundation Settlement
The weight of a retaining wall can cause the soil underneath to compress or subside. This will cause the height of the wall above the grade to shrink.
In conclusion, when designing a drainage system for a segmental retaining wall, an all-around perforated pipe* is the best choice. It allows for more efficient drainage, distributes water more evenly, and helps to prevent water from pooling and exerting hydrostatic pressure on the wall.
This is a drainage gravel that is placed behind the wall for drainage and also approx. 100mm in the bottom of each post hole. On average the quantity of gravel needed is calculated at a 300-400mm width x the length of the wall x the desired height.
Weep holes are crucial for ensuring proper drainage, maintaining the wall's stability, and prolonging its lifespan.
All retaining walls require adequate drainage systems to make them safe and sturdy.
Backfill the wall with gravel or sand. If you use sand, first cover the backside of the retaining wall with landscape fabric. This will keep the sand from seeping between the blocks. If you're backfilling with gravel, you can pour the gravel after every course you lay.
As per the Code- IS 456 : 2000 Clause 20.1, the stability of the retaining wall against overturning should be ensured that resisting moment should not be less than 1.4 times the maximum overturning moment. If the dead load provides restoring moment , then as per code 90% of the dead load should be taken into account.