How to Build a 7 Foot Tall Pressure Treated Wood Retaining Wall

Pressure treated lumber is an ideal medium for building a retaining wall. It is easy to cut to size and stacks tighter than other materials, such as field stone. No mortar or additional adhesives are required for a sound wooden retaining wall as long as a few building principals are adhered to. Most retaining walls are generally 3 to 4 feet in height. For areas where that is an insufficient amount of retention, it is advisable to build several, shorter, terraced walls for steep or sever slopes. A wooden retaining wall constructed to a height of 7 feet is possible, but the same effect is more easily and effectively achieved with multiple walls.

Shovel or backhoe
Crushed gravel
Tamper
Perforated drain pipe
Washed gravel
Re-bar
Spikes
Sledgehammer
Reciprocating or hacksaw
Drill with boring bit for re-bar and spikes
Tape measure
Level
Safety glasses
Gloves

Instructions

Preparing the Site
- 1
  
  For large walls, mechanical equipment will be needed.
  
  Excavate the area to receive the wall. Dig a trench deep enough to accommodate 4 to 6 inches of compacted gravel and two full courses of treated timbers. Dig the trench at least 1 foot wider than the width of the treated wood and at least 1 foot longer on each side of the wall.
- 2
  
  Ensure that the trenches are measured for proper locations.
  
  Dig trenches parallel to the trench for the base for "dead men" and perpendicular to it for the headers. Plan to install headers and dead men at approximately every third course for maximum stability.
- 3
  
  Limestone is a common material for crushed stone.
  
  Fill the base trench with approximately 2 inches of crushed gravel. Tamp firmly and add another 2 inches of gravel. If applying 6 inches of gravel, repeat. Ensure that when the top layer has been compacted and that the service is level for the first layer of wood.
Building the Wall
- 4
  
  Re-bar is available in many sizes and can be cut to desired length.
  
  Lay the bottom course of the wall atop the level gravel base. Every2 to 3 feet along the wall, drill a hole from the top-down into the gravel for the re-bar.
- 5
  
  Warn others in the area when using a sledgehammer.
  
  Cut the re-bar to the desired length with a reciprocating or hack saw. For maximum stability, it needs to be long enough to go into the gravel and ground at least 18 inches, and more if possible. Drive re-bar pieces into the bottom course of wall with a sledgehammer and wear safety glasses while doing so.
- 6
  
  It is critical for stability that the bottom courses are level.
  
  Lay the second course of wall atop the first course. Ensure that the seams overlap and that the wall is still level.
- 7
  
  Ensure that your drill bit is sharp.
  
  Drill holes in the second layer, just as was done in the first, ensuring that holes do not line up with the re-bar in the bottom course. With the sledgehammer, drive spikes into the holes, connecting the second layer to the first.
- 8
  
  Use flexible drain pipe.
  
  Lay the perforated drainage pipe behind the wall. It needs to extend beyond the length of the wall on both ends to carry water away from it. The weep holes need to be facing up.
- 9
  
  Pea gravel is most often used for drainage.
  
  Fill the trench over top of the pipe with round, washed gravel. This can be filled up to the top of the second course of wall.
- 10
  
  Spikes come in lengths up to 12 inches long.
  
  Lay the headers at the wall's ends into the slope. These must be level. Use re-bar to attach it into the ground as with the wall base course. Use spikes to connect the end into the wall.
- 11
  
  Dead men and headers are constructed of the same treated lumber as the wall.
  
  Lay the dead men at the other ends of the header, parallel to the wall, ensuring they are level. Drive re-bar as before into the ground and spikes into the ends to connect to the headers.
- 12
  
  Keep the excavated soil nearby for easy access when back-filling.
  
  Back-fill with the excavated soil the front of the trench and over top of the first headers and dead men. Compact with tamper if necessary.
- 13
  
  Continue ensuring that the seams of the wood overlap.
  
  Continue laying wall courses just as the first two were laid. Continue checking for levelness and connect each successive layer to the one below it with spikes. Cease at the desired 7-foot height.
- 14
  
  Ensure the headers and dead men are securely fastened before back-filling.
  
  Continue laying the headers and dead men as you continue to build the wall. These add considerable stability and strength to it.
- 15
  
  A sufficient amount of gravel will pull the water down into the drain pipe.
  
  Add the round, washed gravel over the drain pipe as you go. This can be done until approximately 1 foot from the top. Use the excavated soil as back-fill the remainder of the way.

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How to Build a 7 Foot Tall Pressure Treated Wood Retaining Wall

Instructions

Preparing the Site

Building the Wall