How to Build Retaining Walls
Decide what type of wall you want to build based on budget and style preference. Consider site requirements and size requirements. If the wall is more of a garden wall (more decorative than structural) you have more choices. A dry stack stone retaining wall and pressure treated timber walls will be the easiest retaining walls to build. Garden walls built from segmental block retaining wall systems will be maintenance free and last longer than wood. A masonry wall with blocks, mortar, and stacked stone or flagstone veneer will be the most time consuming. Stone masonry work is a skilled artisan talent. I do not recommend this kind of project for a do-it-yourself-er. Read more on wall types on our Retaining walls page.
If the wall will be over 3’ tall, you should check local ordinances with your local building department. Retaining walls larger than 2’ should have drainage gravel installed for the first 6-12” behind the wall until the top 6”. The top should receive back fill soil that will restrict water flow through the soil. For most segmental retaining walls over 3-4’ tall, there should be geo-textile re-enforcement fabric every 2 courses running as far back into the back-fill soil as the wall is tall. Engineering suggestions should be followed with or without local ordinance requirements. Drainage measures should be taken for pressure treated timber retaining walls or segmental block retaining wall systems. The engineering has already been done on the segmental systems. Always follow the manufacturers product specific engineering requirements for foundation, drainage, height, back fill compaction, and geo-grid placement to build a safe, long lasting retaining wall.
How to Build a Retaining Wall
Placement, Footing, & Excavation
Building a retaining wall starts with determining the height, length, and location of the wall. Place one end of a long 12’+ board up hill from your intended wall location. Now drive a stake at the starting elevation. Drive a tall stake in the ground where you think you want the center of the wall to be. Place a level on the board and raise the board until level, then clamp it to the stake. Now measure from the bottom of the board to the ground at the lower stake. This will be the height of your wall.
If you are happy with this profile, you need to determine how far into the hill you want to dig to place the base of the wall. Ideally you want to dig out the same amount it will take to fill the back side of the wall. Dig a hole at the location you decide on as a marker for all the other excavation. Now dig back to that marker and begin leveling the base as you go. Drive short stakes in the ground at either end of the wall to pull a leveling string between. Hang a line level on the tight string and level the string by raising or lowering the string. Excavate until you are within a ½” of level for the entire footing area. You can cheat by using more sand to raise the lowest end but be careful. More sand or over-excavating means more compacting. You never want the bottom of the base course of blocks or timbers sitting out of the ground. Try not to build up the sand taller than you are willing to back fill with soil or better yet, dig your footing into the soil deep enough to create a slight trench. After the above steps, wood vs. block steps are different. Skip down the page for block step by step.
How to build Retaining Walls
|Block Walls||Natural Stone Walls||Timber Walls|