This is so that when water gets into the space it does not become bogged down in soil but instead can flow down the wall to the drains or weep holes.
Gravel behind retaining wall.
Compacted native soil can be used to backfill the rest of the space behind the wall.
Round rocks such as pea gravel rolls and dislodge under pressure resulting in failure of the retaining wall.
Drainage gravel is essentially used in any location where you need water to run freely and with minimal resistance.
The most common usage is behind retaining walls or sub surface drainage trenches running underneath lawns and gardens.
The various sized crushed gravel with the fines helps ensures for appropriate compaction.
Soil holds water so the dirt will expand and contract during winter thus pushing on the wall and eventually toppling it over.
Second a retaining wall must have properly compacted backfill.
When building a tiered set of retaining walls position the higher wall behind the lower wall at twice the distance as the height of the lower wall.
When we build a retaining wall we don t only hold back the soil we.
The wall gets its strength from a sturdy base consisting of gravel.
For example if the lower wall is three feet.
A retaining wall must have the strength to hold back the weight of the soil plants and sometimes small structures behind it.
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.
For proper drainage the first 12 inches of space behind a retaining wall should be filled with crushed stone or gravel.
Next compact it and level it using either a hand or mechanical compactor.
Every landscape project is different and may require different quantities and sizes of drainage material.
Blocks or stones then a layer of gravel for drainage then the landscape fabric then the soil.
This video shows how a retaining wall should be back filled to allow for maximum drainage.
Use crushed stone behind the wall loose gravel and stones don t hold water like soil does.
Backfill refers to the dirt behind the wall.