January 22, 2016

Planning and Estimating your Segmental Retaining Wall

Our backyard wall was going to be a big project for a small backyard.  We needed to have a staging plan for all the material, but before that we needed to estimate the project and figure our budget.  The first step in building a retaining wall is to make a plan.  A good plan will lead to a good project.    To start, figure out how much grade change you are working with.  In our case we had around 7 ft.  We decided to cover this height with two terraced walls.  But how tall should each wall be?  We decided the lower wall should be about 3 ft tall for easy access for planting and gardening and the upper wall should cover the rest of the grade change and be as close to the property line as possible. 

Now that we knew the rough wall height and wall length (property line length) we used the incredibly easy AB Estimating Tool that we downloaded from allanblock.com.  When using this great tool, I had to remember to add a little to the wall height for the buried block.  You can also use this estimate to calculate the amount of wall rock and infill soil you will need.  Don’t forget to consider equipment rental such as a skid steer, plate compactor, diamond saw and maybe even a wet saw for cutting caps at the end.  It all adds up and if you plan ahead you will limit the surprises to your budget during the process.

How about staging the material?  I think a lot of do-it-yourselfers like me, forget that with a project of this magnitude you need to store/stage a lot of material.  Our project had 23 pallets of Allan Block, 3 truckloads of washed wall rock and 1 truck load of sand, drain piping and geogrid.  We also had to have a place to store the spoil, or the earth that we removed during the excavation of the hillside.  This was a huge pile that was there from day one until the end of the project when it was used as topsoil backfill.  Because we had a good plan for all the materials, the neighbors were surprised we had space to actually build the wall!