What do you recommend for retaining walls, pressure-treated lumber or mortarless block?
– A.B., Fairfax, VA
There are several factors to consider when installing a retaining wall. First, you need to know whether drainage is an issue
“Well made walls are backfilled with gravel for drainage and have slotted pipes covered with sleeves that drain most of the water away,” explains Bernard Kelly, owner of Australian Landscaping and Construction. “But still, every wall directs water toward its base, and put simply, water behind a wall makes wood rot and fail.”
Next you need to consider price. Wood is generally cheaper, so it’s still commonly used. “…although wood prices are rising and companies like Allen Block are developing cheaper types of block with simple and faster installation procedures,” Kelly notes.
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Another thing to consider is whether you’re planning to sell your home in the near future. If you are, you may be tempted to take the cheaper option, but Kelly explains that most home buyers are very mindful of the fact that wood rots, and make allowances that are sometimes out of proportion to the price difference between wood and block walls.
Building a retaining wall involves many different issues – soil type and water control are critical, with wall failures often being attributed to contractors with little or no experience. “State regulations restrict the building of large critical retaining walls to contractors with a Class A license, so the first thing to do if you’re considering a retaining wall is to make sure the contractor has a Class A license,” Kelly advises, adding that Australian Landscaping and Construction is fully licensed and insured.
Whichever type of wall you choose, make sure the installers are experienced with that type of wall. “I insist on the experienced wood installers installing wood walls and the experienced block installers installing block walls, and not mixing my teams,” adds Kelly, who specializes in difficult drainage sites and almost always recommends mortarless block walls.
“Remember, the pyramids were built with mortarless block,” Kelly concludes.
