How To Backfill a Retaining Wall?

Backfill surrounds your retaining wall that provides adequate drainage and water rerouting which is made out of dirt and gravel.

Backfill is an essential part of retaining walls because it prevents drainage issues or water from building up behind your retaining wall.

One of the main causes of retaining walls failing is poor drainage or insufficient backfill.

This is why having enough backfill behind your retaining wall is crucial.

Best Way to Backfill a Retaining Wall?

You must guarantee that your retaining wall has enough backfill to construct a solid, drainage-optimized foundation.

The steps for correctly backfilling a retaining wall are listed below; if you have any issues, get in touch with our retaining wall specialists.

Considering Drainage:

You must first take the wall’s drainage system into account.

A footing drain is shown by your engineer, right?

Installing a perforated drain pipe behind the footing that drains into “daylight” further down the hill is always a good idea, even if they don’t.

This aids in keeping water from accumulating behind the wall.

Using filter cloth around the pipe is one method for preventing rapid clogging of your drain line.

Rolls of perforated tubing that have filter cloth wrapped around them are frequently available for purchase; these are simple to use.

Backfill Behind the Retaining Wall:

Backfill Behind the Retaining Wall

Backfilling behind the wall can begin once the drainage pipe, concrete wall or first course of the block wall has been installed.

Don’t backfill with the dirt you took out of the hillside.

This procedure stage is where you want to spend the additional cash.

For the backfill material that entails purchasing 3/4″ or 1 1/2″ crushed washed stone.

As a result, the dirt behind the wall will be able to drain to your drain pipe.

As opposed to keeping water in the soil directly behind your retaining wall, this is a far superior choice.

Sandpits, stone pits, and excavating companies all sell crushed stone.

Remember that the stone will be delivered by a sizable dump truck that they will be coming.

Make sure your site has a suitable location to dispose of it.

Make sure there is a way to transfer the stone from the place where it was dumped to the wall itself.

This is frequently a good justification for hiring a bobcat or a small excavator.

Backfill and Compact the Wall:

Backfill and Compact the Wall

Backfill the wall in lifts of 6 to 12 inches or as advised by your engineer.

To compact each lift, you can hire a leaping jack or plate compactor.

If you intend to construct a patio, walkway, or driveway on top of the retaining wall, you need to crush the backfill in lifts.

If the top of the retaining wall is left incomplete, the crushed stone placement has already reached 90% compaction, which is acceptable for a landscape.

For guidance on backfill techniques, always consult your engineer.

Ask the engineer for more information without hesitation.

Filter fabric layer and topsoil layer:

Filter fabric layer and topsoil layer

The wall is now almost completely backfilled.

You should place a layer of filter cloth before putting the top layer of dirt or the foundation on your patio or driveway.

This stops soil or base material from settling into the spaces between the crushed stone.

Once you’ve backfilled your retaining wall, you can add the last layer of material.

Best Backfill for Retaining Wall:

Base Material:

Base Material

The base material serves as the retaining wall’s frame.

Additionally, it offers a level surface on which to set your blocks.

Rock Wall:

How to Backfill a Retaining Wall

Only block walls can be built with Wall Rock.

This is referring to the substance inserted into hollow blocks.

This makes the retaining wall heavier while maintaining the block’s relative lightness.

Additionally, it helps to reduce friction between the blocks, this is a necessary part of hollow blocks.

Stone Drainage:

Stone Drainage

The drainage stone will be positioned 12 inches behind the retaining wall.

Water can freely flow through drainage stone to the drain pipe and out the face of the wall.

Retained Soil:

Retained Soil

In a perfect world, you would utilize the tools at your disposal.

Use only hard soil; do not use clay, organic material like mulch that has decomposed, garden soil, topsoil, or any other soft soil.

Look for processed fill, gravel, sand, or screens if you need to buy backfill.

Importance of Backfilling of Retaining Wall:

Water cannot enter through most retaining walls, thus adequate backfill is required to ensure that your retaining wall drains properly.

Poor drainage from insufficient backfill may cause a deformed retaining wall with ugly bulges or cracks and a build-up of hydrostatic pressure that may cause the retaining wall to break.

Invest the time and effort required to create a solid backfill to ensure that your retaining wall lasts.

Hire a retaining wall backfill firm to install if you don’t have time to produce a backfill on your own.

FAQ- How to Backfill a Retaining Wall:

Q1. What kind of material is ideal for retaining wall backfill?

It is best to grade the gravel before using it as the backfill for retaining walls.

Gravel’s low void ratio indicates that there won’t be much lateral load.

Weep holes should also be present to allow any leftover water to drain.

Q2. What type of rock is used as a backfill for retaining walls?

Crushed stone rather than naturally occurring gravel extracted from a pit is preferred by our specialists as the base material.

The cost of crushed stone is slightly higher.

However, it offers greater drainage that requires less compacting because of the stone’s sharper angles and stays that way once compacted.

Q3. What kind of soil is ideal for backfilling?

There is a small number of fine particles mixed in with the gravel and sand.

This is a top-notch backfill since it compacts easily and offers good foundation stability.


It’s a good idea to be aware of what’s happening in your backyard whether or not you hire a retaining wall professional.

The backfill of a retaining wall depends on the kind of wall you are building.

If you are constructing a wall out of poured concrete, you should postpone any backfill work until after the wall has been constructed.

And building a wall out of modular blocks, you should backfill as you go.

Hello and welcome to House Modify! I am Rahul and I am passionate about everything related to design, decoration and renovation. I am a serial renovator, currently working as a civil engineer. Take a look around, leave a comment and don't forget to subscribe to my emails so you don't miss out!

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