how much sand below first course of stone blocks for a retaining wall

by Desmond Wunsch 6 min read

Bedding sand
After compacting, spread a 1-inch layer of coarse sand or ¼-inch minus gravel. This layer is used for bedding the first row of wall blocks.
Jun 1, 2018

Full Answer

Can I use sand instead of gravel to level retaining wall blocks?

One piece of gravel can throw the blocks off. Can I use sand instead of gravel to level the blocks? -Kevin To keep the blocks on your retaining wall level and structurally sound, you need a base layer of several inches of well compacted, sharp gravel.

How deep should retaining wall blocks be buried?

To keep the bottom row of blocks from pushing outward, bury the lowest section of a retaining wall. The general rule of thumb is to bury about one-eighth of the height of the wall. For example, if your wall will be three feet (36 inches) tall, the first course of blocks should start five inches below soil level.

What size stone do I need for a retaining wall?

Stone Needs. 1. Measure the length in feet of the desired wall. Determine the desired height in feet and add .5 to this measurement. The .5 accounts for the 6 inches of stone footers that sit underground after retaining wall installation.

How do you measure stone blocks for a retaining wall?

Measure the average length and width of the stone blocks in inches. Multiply these two numbers to determine the average measurement of each block in square inches. Divide the square inch measurement of the wall by the square inch measurement of the average block, instructs Lowe's.

How much leveling sand do I need for a retaining wall?

1/2″ to 1”Some block manufacturers recommend spreading a 1/2″ to 1” layer of sand on top of the gravel layer, to help with leveling. Be sure to use coarse builder's sand, and tamp it down firmly to keep the sand from shifting and settling after the wall is built.

Should I use sand under retaining wall?

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.

How do you prepare the ground for a retaining wall block?

0:372:58How To Build a Retaining Wall - YouTubeYouTubeStart of suggested clipEnd of suggested clipLevel tamp down the dirt with a hand tamper. And keep it. Level next fill the trench with aboutMoreLevel tamp down the dirt with a hand tamper. And keep it. Level next fill the trench with about three inches of paver base spread it with a rake.

How much base do I need for a retaining wall?

Dig out a trench that is a minimum of 6″ (155 mm) deep plus 1″ for every foot of wall height. Allow 6″–8″ (150–200 mm) of space behind the wall for 3⁄4″ clean crushed rock (this means your trench is a minimum of 12″ or 305 mm wide).

What do you put under retaining wall blocks?

Use crushed gravel to fill in the back and sides of your blocks. Backfill helps with water drainage. Compact the backfill before starting on the next row of blocks. You should clean and sweep the top of each row before placing the next one.

How do you level the first row of a retaining wall?

2:484:19Retaining Wall Base and Block Leveling Techniques Segment 3YouTubeStart of suggested clipEnd of suggested clipHaving a flat concrete surface makes it easy to snap a chalk line for help in aligning your firstMoreHaving a flat concrete surface makes it easy to snap a chalk line for help in aligning your first row of block.

Can you put sand behind a retaining wall?

The base of a retaining wall should be set below ground level. The taller a wall is, the further below ground level it should be set. Crucial for supporting the rest of the wall, a good base is made of compacted soil and at least a six inch layer of compacted sand and gravel.

Does a 2 foot retaining wall need drainage?

Every retaining wall should include drainage stone behind the wall. Though it is a good idea to install a drainage pipe on all walls, there are certain situations where a perforated drain pipe is absolutely necessary.

Why do retaining wall blocks have a Lip?

A lip on the back of each block creates a uniform setback as each course is added. This design causes the wall to angle slightly back into the slope, further improving its holding power.

How do you prepare a base for a retaining wall?

0:041:50How to Install a Retaining Wall Base Course - YouTubeYouTubeStart of suggested clipEnd of suggested clipPlace the blocks tight together checking each block for level and alignment from side to side andMorePlace the blocks tight together checking each block for level and alignment from side to side and front to back. Make minor adjustments by tapping the blocks with a dead blow hammer.

How much gravel do I need for my retaining wall?

Multiply the length of the wall by the desired height, then divide this number by 81 to determine the amount of backfill gravel needed. Add the backfill amount to the base amount to determine the total cubic yards of gravel necessary for completing the wall.

How deep should the footing be for a retaining wall?

The general rule of thumb is to bury about one-eighth of the height of the wall. For example, if your wall will be three feet (36 inches) tall, the first course of blocks should start five inches below soil level. The gravel base should start three inches below this.

How tall can a retaining wall be?

In most states, you can build a retaining wall up to 3′ tall without a permit. The wall featured in this tutorial is three feet high. Landscaping Blocks – Once you know how high your wall needs to be, then you can choose a block to use.

How to build a wall on a slope?

You want your blocks to be perfectly level. To accomplish this, you’ll add a paver base to the very bottom row only, then add the first row of blocks.

How to cut a block with a diamond blade?

If you have an angle grinder with a diamond blade on it, cutting the blocks will be even easier. Again, mark the block all the way around where you want to cut it. Then, grind a groove all the way around the block. Then , take a sledgehammer and a chisel, place the chisel in the groove, and give it a tap.

How to cut a block with a hammer?

Grab a masonry chisel and a mini sledge. Draw a straight line all the way around the block where you want to make your cut. Then, take your chisel and hammer and chisel a notch all the way around the block. Once you have a groove all the way around the block, place the chisel in the groove and hit it a bit harder with the hammer. The block should split pretty nicely.

Is it important to retain a wall?

Retaining wall construction is a labor intensive process. It’s not something you’ll want to do twice. So, planning your wall design and layout is an important step. Not only will it help you achieve a better final result, it will help save you time and effort.

Do you have to grade around retaining wall?

You must plan the grading around your retaining wall so the water drains off your property and away from your house. If you live in a suburban area, you also want to make sure the water isn’t draining into your neighbor’s yard. If you live in a rural area, you’ll want to pay attention to water rights.

What to use to reinforce retaining wall?

After each row is completed, you should use backfill to reinforce the retaining wall. Use crushed gravel to fill in the back and sides of your blocks. Backfill helps with water drainage. Compact the backfill before starting on the next row of blocks.

What are retaining walls made of?

While retaining walls are made out of many types of building materials, a block system is a popular choice due to the easy installation features. The blocks are made from cement and lightweight aggregate materials.

What is the purpose of retaining walls?

Proper installation of landscape retaining walls can make sloping lots usable while managing both soil and water runoff. In addition to serving a functional purpose, retaining walls also add aesthetic appeal to your landscaping. Use them in home gardens to highlight flower beds, patios, or yard features.

Why do you need to capping a retaining wall?

Capping helps to protect your retaining walls from weather and erosion. There are several options for capping material. For some types of retaining wall block systems, there are corresponding capping stones that are designed to match the design of the wall block.

How much soil pressure does a retaining wall need?

Soil is heavy, especially when soaking wet from a recent rainstorm, so a basic retaining wall (four feet tall and 15 feet long) potentially has to support up to 20 tons of soil pressure.

What materials are used to build retaining walls?

Retaining walls can be constructed using a variety of materials, from poured concrete and large timbers to natural stones, even bricks. For DIY purposes, opt for manufactured blocks that are designed specifically for building retaining walls; a locking flange along the bottom edge creates a secure attachment between rows.

What is the enemy of retaining walls?

Groundwater is the natural enemy of retaining walls. When it saturates clay-type soils, they swell and put excessive pressure on the backside of the wall. To avoid failure, make drainage provisions at the same time as you go about building the retaining wall.

How high should a retaining wall be?

Typically, residential retaining walls are built between 3 and 4 feet high.

How much backfill should I use for a wall?

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.

Why do we need retaining walls?

A retaining wall is intended to hold back soil when there is a drastic change in elevation. Often retaining walls are used to terrace yards that originally had a steep slope. Additionally, retaining walls can help create usable outdoor space as well as control erosion, (see Landscaping a Split-Level Home .) Low retaining walls are frequently used ...

What happens if water goes unaddressed behind a retaining wall?

When drainage goes unaddressed hydrostatic pressure will build up behind the wall and cause damage such as bulging or cracking. There are a number of ways to ensure proper drainage of water from behind a retaining wall. First, is to make sure your landscaping contractor backfills at least a foot of space behind the wall with gravel.

What is the best base for a wall?

The taller a wall is, the further below ground level it should be set. Crucial for supporting the rest of the wall, a good base is made of compacted soil and at least a six inch layer of compacted sand and gravel.

How much does a retaining wall cost?

A natural stone or brick retaining wall laid by a mason can cost upwards of $20 per square foot, and a poured concrete retaining wall will set you back $13 to $18 per square foot.

How high should I bury a brick wall?

The general rule of thumb is to bury about one-eighth of the height of the wall. For example, if your wall will be three feet (36 inches) tall, the first course of blocks should start five inches below soil level. The gravel base should start three inches below this.

What is buried footing?

A buried structural footing is usually required for larger retaining walls. To create this, a landscaper pours concrete below frost level (the depth to which the ground will freeze during the winter). Footings poured too shallow are prone to shifting and moving if moisture in the soil freezes and heaves.

What is gravity wall?

You could also add extra strength with a “gravity wall,” which is so wide that its weight serves as a buttress against the pressure of the soil behind it. This type of wall isn’t common, however, because it requires an extensive amount of stone or concrete for construction.

How to keep retaining wall from pushing outward?

They’re also widely available at most home centers. To keep the bottom row of blocks from pushing outward, bury the lowest section of a retaining wall. The general rule of thumb is to bury about one-eighth of the height of the wall.

What is a step back wall?

This design, known as “step-back construction,” creates a sturdy wall structure that pushes back against the lateral pressure of the soil behind it . Step-back walls can be built by anyone with a strong back and basic construction knowledge, as long as they have blocks designed for retaining wall assembly.

What is retaining wall?

Retaining walls have a wide variety of uses around the yard, all of which involve keeping earth from spilling off a steep slope. They’re indispensable in the creation of sunken patios, walkout basements, and any other hardscape with an abrupt separation of ground elevation. You’ll also find retaining walls in parks and public gardens, where they act as retainers for plants, statues, and decorative landscaping elements.

How thick is sand?

Sand is generally a non-compactable material and tends to move around. Two inches is too thick of a layer in any case. A half inch is on the thick side - just enough to smooth the top surface ofthe crushed gravel. The reason that many do not mention sand at all is usually when they are telling you to use larger gravel without any fines in it because it will eventually slip into the spaces between the stones and cause settling.

Why won't sand sift between gravel?

The sand will not sift between the gravel because the gravel you will want to use will be the same for a wall, i.e what was mentioned above by laag. It has fines in it, hence the name 0-3/4", as in 0" fines to 3/4" rock, and everything in between. These fines at the micro level are shaped like tiny triangles that bind together in ...