Between HGTV and YouTube tutorials, everyone wants to be a DIY-er these days. And with a project like retaining walls, using manufactured interlocking blocks, doing-it-yourself can seem like child’s play.
Of course, you will want to make sure you have the necessary tools on hand—or know which handy neighbor to borrow them from! You will need a shovel, rake, broom and wheelbarrow… plus a tape measure, hand tamper, rubber mallet and caulk gun. And in addition to the block itself (stacking and capstones), you will need gravel, drainage pipe, fabric, extra soil and adhesive. As far as the time it will take, one estimate is that it takes 20 man hours for every 10–15 feet of a low wall.
NOTE: Always check local ordinances before tackling a retaining wall project because the height rules vary by locale.
Preparation is key
As with so many things in life, when building retaining walls great care must be taken in preparing the base. After you mark off where the wall will go, dig out the area to several inches below grade and then fill the trench about halfway with gravel. It is critical at this point to rake the gravel smooth and then thoroughly tamp it down. Once it is compacted and level, you may continue adding gravel as necessary until the desired height is reached. And please, always call 811 before you dig.
Precision is as precision does
As you lay the block, check the level and alignment as you go. Use your rubber mallet for making adjustments. Fill the block cores with crushed gravel, and use the broom to sweep the surfaces clean. Be sure to install the drainage pipe behind the first level of blocks. You do not want water collecting at the base of your wall. Cover the end of the pipe with drainage fabric so it does not clog.
With the next courses of block, just continue the process of filling with gravel, making sure they are level and aligned, and sweeping off the debris. You will want to cover the drainage pipe with gravel and top with soil.
Your final course will be the capstone block, which should be secured using adhesive and a caulk gun.
If you’re an experienced and intrepid DIY-er—as long as your retaining wall is not more than 48” high and you have the proper tools—you should be able to tackle this project.
When to consult with the pros
If you are planning a wall higher than four feet, be sure to check your local building codes and see if a permit is required.
If you find that you want a more creative design, perhaps incorporating curves, steps or columns… or if you simply prefer professional installation… there are many qualified installers available.
And whether you DIY or call a pro, you should absolutely consider “retaining” the services of an engineer for wall heights over four feet. Always check local ordinances before tackling a retaining wall project.