Retaining Walls

Retaining Wall Drainage

Retaining wall drainage is an integral and operative part in protecting retaining walls from standing water. Standing water, and freezing and thawing of water against walls would ruin the integrity of your walls, by creating hydrostatic pressure, making it possible for it to crumble, crack or even fall. It is important to know both the purpose and the fundamentals about retaining wall drainage to find out what will work best for the drainage of your retaining walls.

Proper design of your stone, modular block retaining wall or whatever building material will be complete when you consider proper draining in your plans. Water sitting behind the walls will create what is called hydrostatic pressure, which is lateral pressure that could cause the walls to crack and then crumble. Gravel, sand, netting and weep holes are the old time, ultimate solution to the age old question of how to supply retaining wall drainage to your retaining wall's plans. Pipes can also be considered. Learn all you can to understand the types of drainage systems you can install on your own.

Preventing Hydrostatic Pressure

To truly prevent the lateral, potentially damaging hydrostatic pressure against walls, it is important to keep the water away from the walls in the first place. Near the lowest possible part of the wall's backfill there needs to be holes to minimize any saturation of water in the backfill. Here is how gravel, sand, netting and drain pipes work together, as one example.

The gravel allows water to filter through to the sand. Sand or some other granular backfill against the structure further filter the water through netting, into a wall drain system. The netting helps prevent clogging. The drain would in this case be perforated, which would make weep holes unnecessary. Being connected to the drain pipe prevents hydrostatic build up of pressure against the walls. Do be sure to check with your local codes to find out if you are required by law to build to certain specifications, or to use particular materials.

Retaining wall drainage may allow for you to use perforated pipes or weep holes in the wall. However, do make sure that when you use perforated pipes that you have the pipe collect the water, then drain the water off in more than one place. This will support the retaining wall drainage at the point of the pipe, even if one avenue becomes unusable, such as if it gets blocked for some reason. Although, more likely than not, at some point this will become clogged.

The materials with which you decide to build make a difference in the amount of drainage you will have to build in. For instance, retaining wall drainage on a concrete-structure walls needs to be particularly "on" because concrete will be basically impenetrable, therefore you need to make a route for the water to get out and drain. There are also additional details that you would also want to be cognizant of, soil related.

The Dirt on Walls

The type of soil that you are preparing retaining wall drainage to work in is another consideration. Living in an area with clay, granular backfill might just create a problem in waiting. In this case drains for your walls will be necessary and work in your favor for proper water drainage.

Pretty much, the lay of the drainage-plan follows your designer's plan. It could include something like the example given here, so you better understand how aspects of drainage work together. You might lay perforated pipe wrapped in a mesh sock or netting to prevent clogs. This would sit on a few inches of gravel. It would then be wrapped in landscape fabric at the base of the walls. You might also include weepholes and a couple of avenues for the pipe to drain. Again, providing a couple of ways for the pipe to drain will help if clogs occur.

Beyond Humpty Dumpty and Hydrostatic Pressure

Beyond hydrostatic pressure as an issue on the integrity of your retaining walls and proper drainage of water away from walls, there is one other factor to consider. When you build your walls, beyond retaining wall drainage, the battering of the walls will also prevent tumbling and crumbling. It is in any walls that do not have cables anchored in them or pilings to keep them upright. Battering is basically that the walls are not perfectly vertical. They lean inward, and taper so that they will not fall.

Retaining wall drainage is extremely important. It helps protect the retaining wall from standing water, which can cause damage that can cause the wall to crack and crumble. Of course, also, the main purpose of a retaining wall is to hold back soil from eroding, and one way of doing this then is to properly drain water.

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