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Perforated Drain Pipe Retaining Wall

Three: Levelling The Soil

7 – Drainage & Backfill – Mosaic Retaining Wall Installation

It is always important to level the soil in the drainage trench in order to provide a firm base to lay the pipe onto. At Coastal Drains, we have the latest equipment to level the soil to an extremely high standard. Levelling the soil properly will ensure your perforated pipe installation lasts and works properly for many years to come.

Does A 2 Foot Retaining Wall Need Drainage Summary

Ultimately, the goal is to get rid of the water in and around the retaining wall. This prevents damage, seepage, and in general any changes to the wall other than natural aging. Does a 2 foot retaining wall need drainage? In our opinion, yes. But ultimately, it is up to you. Hopefully this has helped you consider some ways of accomplishing it if you choose to incorporate drainage into your backyard retaining wall project.

Where You Can Look For Drainage

The best way to see if your retaining wall is draining water correctly is to check if there is water coming from weep holes after rain. If the retaining wall is bulging, uneven or falling apart, its likely that water is not draining correctly. The weep holes can also be obstructed by mortar, pests and other debris, so its important to check and clean them regularly to the best of your ability.

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The Importance Of Retaining Wall Drainage

Retaining walls are useful structures that form a transition between areas of different elevation. Retaining walls allow steep, unusable slopes to be avoided. A retaining wall will make use of the vertical forces from the wall itself and any soil above the walls footing to resist the lateral forces from the soil being retained. This balance can be upset when additional lateral forces act on the wall.

When water accumulates behind a retaining wall, the lateral forces acting on the wall increase. The more water that has collected behind a retaining wall, the greater the hydrostatic pressure on the wall will be. If the overturning moment exceeds the resisting moment , the wall will fail.

There are several ways to prevent water from building up behind a retaining wall. Weep holes should be drilled through the wall. Weep holes allow water to escape from behind the wall. These holes should be regularly spaced in the horizontal direction. Retaining walls with a height greater than a few feet should also have weep holes that are regularly spaced in the vertical direction, forming a grid pattern.

The grading behind a retaining wall also has an effect on the buildup of water. The soil behind a retaining wall typically slopes toward the wall. This causes surface water to move in the direction of the wall, which can lead to accumulation. Grading can be used to reduce the amount of water directed toward the wall.

Why Do Retaining Walls Need Drainage

DRAIN TILE : perforated pipe surrounded by granular fill used to ...

A retaining wall is essentially an artificial hill that prevents soil from moving downslope. If there isnt any drainage system in place, this could cause problems for your retaining wall.

For example, if too much rain falls during heavy storms, the soil behind your retaining wall may become saturated.

As this happens, the weight of the soil above the wall increases, causing the soil to shift. When the soil shifts, it can damage your retaining wall.

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Four: Cover With Gravel

Filling the trench with gravel will prevent the soil from sinking and clogging up the pipe when it rains. Gravel helps to keep everything in place, ensuring your perforated pipe lasts and lasts. It is important that the trench is filled with gravel up to 2 inches so that the pipe can fit comfortably on top.

Why Proper Drainage Is Important For Retaining Wall Performance

A retaining wall is built to hold back a certain amount of soil. The design of a properly-built retaining wall resists the force of the soil behind it and prevents caving, buckling, or leaning. However, retaining walls are built with a certain capacity in mind. When water gets behind the wall, it puts additional pressure on the structure, which can result in the overall force exceeding the walls ability to resist.

This is what good retaining wall drainage looks like:

When the wall is no longer able to resist the force behind it, the weakest part will give. Sometimes, this means that the wall will develop a bulge at this weak spot. In other cases, water pressure behind the wall may cause it to lean outward. If the pressure is consistent and forceful enough across the wall, it may even buckle.

Conversely, this is what bad retaining wall drainage looks like:

Okay, lets dive into all the details of this diagram and how to make your retaining wall drain successfully.

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Installing Proper Drainage For Retaining Walls

Retaining walls, as part of a landscape or garden, are a very common occurrence. They are used in many areas, from a foot or so high, to tens of feet high, they can be strictly for decorative purposes or they can be installed to hold back earth in order to level or grade a property, as shown in Figure 1.

Figure 1 – Retaining wall used to grade a property.

Making or constructing a retaining wall that is taller than a couple of feet requires some thought and planning to ensure that it remains in its installed position and does not move.

Whether or not a foundation is required in order to support the retaining wall is dependent upon the height of the wall and what the condition of the material is that the wall will be sitting on. If you are contemplating placing a retaining wall, that is more than a couple of feet high, on soil that is not compacted or soil that is easily compacted you should consider the installation of a concrete footing in order to provide foundation stability and to prevent the retaining wall from settling.

Figure 2 – Installation of a layer of crushed gravel and perforated drainage pipes, running parallel to the retaining wall at its base

Although there are minor difference in the stability of the wall created by the material it is constructed from, proper drainage applies to retaining walls made of any material including interlocking retaining wall blocks, pressure treated lumber, railway ties or rocks.

How To Install A Perforated Drain Pipe

French Drain – Retaining Wall Drainage

In order for perforated drain pipes to work properly, they must be installed on a slope so they can provide optimal drainage.

When a perforated drain pipe is installed by our professional team, it provides an effective solution to any problems you are experiencing with excessive groundwater near your property. Installing a perforated drain pipe can be done in six easy steps.

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How Big Should Weep Holes Be In A Retaining Wall

What size should weep holes be in a retaining wall? Better to have more weep holes than less, 24 spacing is a fairly reliable start for 1.5 Diameter weep holes in a wall not exceeding 4ft. The higher the retaining wall, the larger diameter the weep holes.

How to properly add drainage to your retaining wall?

Drainage Stone. All walls should include drainage stone,even if they dont require a drain pipe.

  • Filter Fabric. Place filter fabric*or landscape fabric above the drainage stone and below the topsoil.
  • Perforated Drainage Pipe. The perforated pipe*should be slotted all around the pipe.
  • Do I need a drain pipe for my retaining wall?

    When you are installing the landscaped earth, which the retaining wall is designed to hold up, you should fit in some PVC pipes. These will allow water to drain out of the earth, and prevent your soil from getting waterlogged and excessively heavy. No Stones Behind the Wall. When you are constructing the wall, add a layer of loose rocks and stones between the earth and the wall. This will help provide drainage, particularly during heavy rains.

    How to install drain pipe behind retaining wall?

    Base First,a retaining wall must be built on a suitable base.

  • Backfill Second,a retaining wall must have properly compacted backfill.
  • Drainage Third,since most retaining walls are impervious,which means water cannot pass through the wall itself,efficient drainage is crucial.
  • Do I need drainage behind my retaining wall?

    Versatile And Easy To Work With

    Hydraway simplifies drainage work in construction with products that combine versatility and ease of transport and installation.

    Our products feature flat strip drains and drainboards, which cuts initial labor costs while performing better 15, 20 and even 30 years down the line. By relieving hydrostatic pressure and reducing erosion, Hydraway drainage systems keep civil infrastructure in top condition for longer.

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    We Provide Drain Installations

    If you are considering having a perforated drain pipe installed in your property, whether domestic or commercial, call our team today. We are proud to provide professional drain installation carried out by our team of fully-trained and experienced experts. Whether your installation requires a small excavation or a deep dig excavation, we are qualified to undertake these works responsibly on your behalf. Why choose Coastal Drains?

    • Same day service

    How To Set Up Your Retaining Wall To Drain Properly

    Drain Pipe For Retaining Wall

    The process of making sure that a retaining wall drains properly is relatively simple, but it is not very flexible. Although there are exceptions, most retaining walls require gravel backfill, soil compaction, pipe or toe drains, and weep holes. Together, these four features will provide adequate drainage for most designs. Only a few types of walls will not require all of them. We recommend getting a professional to help you install, but if you want to DIY, these steps below and other tips in our in-depth DIY guide can help you along the way.

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    What Happens If There Is No Retaining Wall Drainage

    If there is no drainage, water will compromise the safety and structure of your retaining wall. Its vital that the wall is repaired or replaced if measures to ensure drainage werent taken. This can lead to an extensive amount of damage on the property, the expense of repairs and installation of a new wall. Thankfully, early warning signs of retaining wall failure are easy to spot and inadequate water drainage may not be the only cause.

    The Perforated Drain Pipe And What You Need To Know

    A perforated drain pipe is one of the most essential aspects of your drainage system. Perforated drain pipes provide drainage solutions to excessive standing water near the building foundations of your domestic or commercial property.

    Perforated drain pipes are most commonly used to move rainwater away from the house so that it can drain elsewhere. Commonly situated near the base of your homes foundations, perforated drain pipes help provide optimal drainage for your property so that the likelihood of standing groundwater is significantly reduced. Find out more about perforated drain pipes and how they can prevent water damage to your property below.

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    Drainage Tips For Retaining Walls

    Retaining walls are the perfect blend of function and aesthetic. They help protect your property, home, and surrounding landscape from natural elements by adding a unique design element to your yard. When designing and constructing a retaining wall, there are several things to consider, from what materials will be used to what function the structure will serve. Proper drainage is needed for any retaining wall to function correctly and stay standing for years to come.

    How To Drain Water From A Retaining Wall

    Diy French drain and retaining wall

    The first method of draining water from a retaining wall involves installing drains at the base of the wall to collect excess water.

    These drains are usually placed near the top of the wall to ensure theyre located below the level of the surrounding land.

    Once the water collects in these drains, it can then be pumped up to higher areas.

    In order to install drains at the base of a retaining wall, youll need to dig trenches in the soil. You should make sure to leave about 6 inches between each trench.

    Next, youll need to cut holes in the side of the trench. Make sure to drill straight down into the center of the hole. Then, youll need to insert a pipe into the hole.

    Finally, youll need to fill the hole back in.

    Another option for draining water from a retaining wall is to install perforated pipe along the length of the wall. Perforated pipe has small holes drilled throughout its length.

    The purpose of this pipe is to help water pass through the wall while still allowing air to circulate.

    Youll want to install a perforated drainpipe at least every 20 feet along the length of the retaining wall. This will help prevent water from pooling in one spot and building up pressure.

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    Dont Skimp On Gravel Amount

    Add an angular aggregate clean, crushed stone or gravel between 1/2- and 3/4-in. as a base under the retaining wall and as back fill behind it. Convention says to add at least 12 inches of gravel backfill, but Christoforas motto here: The more the better. Depending on the size and scope of the project, the minimal increase in cost of installing 24 inches of gravel behind the wall will provide increased drainage and maximize the structural integrity, he says.

    For existing walls, you may want to excavate to see if the gravel is at that 12-inch minimum. If needed, you could dig down far enough to see if there is the necessary footing drain and gravel under the wall as well. Just be careful not to undermine the wall.

    Dont Skip The Footing Drain

    Nearly every retaining wall should have a footing drain at its foundation. These have a pipe leading out, AKA daylighted, so water can flow out. Given the cost of materials and the effort required to build any retaining wall, the increased cost of the footing drain is small compared to assuring the wall will perform over the long run, Chirstofora says.

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    Drainage Systems For Retaining Walls

    Drainage behind a retaining wall requires both proper backfill and drainage pipe. Backfill consists of a 3/4 angular crushed clear stone at a minimum 12 behind the wall and continuing vertically up that wall. It is a clear stone meaning that it is a washed aggregate that is clear of fines. This allows for the water that enters the system to permeate through the backfill down to the base of the retaining wall.

    Once the water gets to the base of the retaining wall, it needs to be collected and exited out of the system. Some of the water may permeate through the subsoil, though heavier clay that your region may have will cause water build up.

    Pipe needs to be installed behind a retaining wall to collect that water build up at the base. This drainage pipe should be perforated, allowing the water to enter and exit the pipe on its way out of the system. The pipe should have a slope towards the lowest area or where water will be exited at a minimum slope of 1/8 per foot. Additionally, every 50 feet of retaining wall should have an exit point through the face of the wall.

    This is accomplished with a T in the drainage pipe with a pipe or other attachment to extend past the face of the wall at a distance that allows water to flow away from the face of the wall. The slope of the pavement or ground at the face of the wall also needs to slope away from the wall itself so that water does not flow back towards the retaining wall causing more issues.

    & nbps

    Positive Gravity Flow Through The Drain Tile

    French Drain along a foundation.

    STEP 1: Compact the soil and build the base course of blocks for the wall.

    STEP 2: The water circulating into the back cut and the compaction zone needs to enter a pipe with an appropriate pitch to allow proper drainage. The pipe needs to be set at the right height across the entire length of the wall. In this case, we need to add a crusher run material behind the wall and compact it. The crusher run is used to build up an impermeable backfill layer to establish the correct elevation for the pipe to be able to capture the water and direct it out of the SRW system.

    We have about 6 inches of pitch over 50 feet. The national concrete and masonry association requires that the pipe for drainage behind the wall should be exposed to daylight at least every 50 feet. The perforated pipe should have a 4 diameter.

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    Ensure Theres Enough Slope

    Even with lots of correctly installed drainage around your retaining wall, if the soil on the other side doesnt slope away sufficiently, that water wont go anywhere. Any amount of slope will do, provided it doesnt reverse a short distance away.

    Keep in mind where the water will end up. You dont want the excess water draining onto someone elses land or into a pond, lake or river. Other options, if youre in a pinch: Build a French drain or a dry well, where water can flow into a gravel trench or pit and then be absorbed into the ground, Christofora says. Theyre both fairly involved projects, but can be grassed over or turned into attractive landscape features.

    Flat Yard Drainage Alternatives

    If you have a flat yard and draining to daylight isnt possible, a dry well might be a good solution. A dry well is usually built using a precast concrete or plastic container filled with large rocks. You then pipe your drainage water to the dry well. This creates a place for the water to pool and slowly percolate into the ground. Depending on your soil type this may be a good solution.

    If you have a low spot on your property but its far away from where you are building the wall you will want to pipe the water to the low spot. To do this you can connect a pipe to the perforated pipe in the trench and run it to the low spot on the property.

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