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How To Build a Cinder Block Retaining Wall

How To Build a Cinder Block Retaining Wall

Retaining walls are the structure that holds back soil from eroding from your yard. It also supports leveling a patio section and adding a planting bed in your garden.

Compared to concrete, cinder blocks are lightweight and easy to install. As a result, constructing a retaining wall is not difficult. You should be able to finish it in a few days.

Since retaining walls are critical, be aware of their failure while building them. The important aspect while building a retaining wall is to have a compact base. The rest of the directions are unchallenging if you follow a few step-by-step instructions.

Things To Remember

There are certain things you should consider you start digging your yard.

  • It would be best if you had a building permit for retaining walls taller than three feet. It is important to check whether the location has underground pipes and wires.
  • Inform local utilities a few days before starting the construction.
  • Ask for manufacturers’ instructions if the wall is above 4ft.
  • Get help from friends or families to assist, as the construction requires minimal heavy lifting. 

Materials Required

  • Spray paint or strings
  • Hand tamper
  • Shovel
  • Constructive adhesive
  • Broom
  • Gravel
  • Cinder blocks
  • Sledgehammer
  • Wheelbarrow
  • Chisel
  • Safety glasses and gloves

Steps To Build a Cinder Block Retaining Wall

Here are important steps to follow to build a cinder block retaining wall.

Determine The Base And Footing 

It is very important to have a compacted base to make the wall solid and straight. Ensure the base is twice the width of the blocks you are installing. Use a measuring tape to measure the position of the retaining wall.

Mark The Location

After footing the area, mark the location using stakes. Tie strings on each end to make the excavation easier. You can also spray paint to draw the area you plan to excavate in a curved retaining wall.

Dig a Trench

Start digging the marked area. The depth must be at least 4-6 inches deep and 24-28 inches wide for a 4ft wall. It must be buried 1 inch deep for every 8 inches of the wall height. You should measure it according to the wall height. Leave 12 inches behind the wall to add gravel. Keep the base flat with the help of a tamper. You can rent it if you do not have access to it. 

If you are working in a sloped area, you should excavate a stepped trench. It will make the blocks level properly. 

Add Paver Base

Add Paver Base

Now you can start spreading the crushed rock base onto the trench. The gravel base must be six-inch deep to make it strong. Spread it thoroughly using a rake. Tamper the gravel to make it flat as possible. Keep compacting until it is 1 inch below the top.

In the case of a sloped yard, you should lay the gravel one block to another block. Spread the paver base, install the first row blocks, and repeat the same process.

Start Installing One Block At a Time

Start Installing One Block At a Time

Place the first block carefully. If the first Base is weak, the whole foundation will be fragile. Using a chisel and a sledgehammer, break off uneven flanges so the blocks will sit even. For straight retaining walls, use a string line to ensure the blocks are exactly placed. Place the row leveled from front to back and side to side. Remember to leave a 12-inch gap behind to backfill it with crushed rocks to support the wall. 

Add Gravel Behind The First Row of Blocks

Add Gravel Behind The First Row of Blocks

The majority of retaining wall failures are the moisturized soil behind the wall. To prevent this failure, you should add gravel to the cavities of the block. It will prevent moisture damage on the blocks. It will also filter mud and water when it rains. Use ¾ inch sharp-edged gravel for excellent compaction. Also, backfill the area with crushed rocks; it will help stop soil erosion and ensure proper drainage. You can add drainage pipes for better drainage in the rainy season. 

Sweep the Blocks With a Broom

Using a broom, brush off dust and debris from the top of the blocks for the next step. Adding the blocks without brushing dirt can cause uneven management.

Level Rest of The Blocks

Level Rest of The Blocks

It is easy to level the rest of the blocks. Make sure all of the blocks line up according to the location. Keep adding the gravel while adding the blocks. Add construction adhesive to top blocks. It will help the wall to hold better.

Add Top Wall Cap

You can add a top wall cap if you want. Glue the top block with the help of adhesive. Keep brushing the dirt off the blocks before adding the adhesive. 

Cover The Wall With Topsoil

Finally, cover the wall with topsoil and add plants to complete the process. Also, backfill behind the wall with soil instead of gravel. 

Avoiding Retaining Walls Fails

Some common mistakes can lead to failing retaining walls. You can notice signs like leaking and crumbling on concrete or cinder block walls. Consider the following things to avoid it on cinder block retaining walls.

  • Choosing the right size of cinder blocks: The size of the cinder blocks varies according to the size of the walls you plan to build. If you want your wall to be 3 ft high, you should purchase 12″ long x 4″ high. If the wall is above three ft., consider building it with a standard size of 16″ long x 8″ thick.
  • Proper drainage: Ground is a big enemy to remaining walls. If you fail to address small details of the drainage system, the surface water can damage the whole foundation. The accumulated water behind the walls can make it weak and probably break down in no time. 
  • Maintaining the wall: You must inspect it from time to time to ensure it needs some weeds to pluck out. Also, ensure the back of the wall is filled for drainage. 
  • Level the blocks: The blocks need to be properly balanced to make the wall sturdy. Consider the wall a failure if the first row of blocks is not leveled. 
  • Weak Base: To have a strong retaining wall, you must first have a strong base. The Base must be deep enough to resist the weight of the whole wall.
  • Use safety measures: You can be injured while constructing a retaining wall without proper safety gloves and masks. 
  • Height of the wall: Without professionals’ help, you can build walls up to 3-4 feet high. Height above 4 feet should be engineered by experts only. You have to check the quality of the soil and blocks before making a long wall.