Are you in desperate need of a new retaining wall but not sure which type is right for you?

As retaining wall builders, we’ve made it our goal to educate consumers on the differences between different retaining wall options. This way you have all of the information you need to choose the best option for your home. 

In this article, we’re going to give you an overview of the key differences between two popular retaining wall options. These are timber and block retaining walls. By the end you should have a basic understanding on retaining wall installation, cost, and maintenance requirements. 

Timber Retaining Wall Vs Block Retaining Wall Construction 

One of the biggest factors that differentiates retaining wall types is how they are built. 

Timelines for a retaining wall project can vary dramatically depending on the unique conditions of your property. A small wall could be built in as little as one day and a large wall that wraps around your property could take several weeks to complete. 

There are some similarities between the two retaining wall methods mostly in the excavation and base preparation phases. 

Timber Retaining Wall Construction

Timber retaining walls are typically excavated to a depth of 15-18 inches. It's time for compaction with a heavy duty 10,000 lb force rated plate compactor once excavation is complete. A woven geotextile fabric must be installed to separate the subsoil and bridge any minor voids so that your new retaining wall doesn't shift. Between 6-10 inches of crushed gravel is installed atop the fabric and compacted in 4 inch lifts to ensure proper compaction. Before laying the first tier of Timbers a 1 inch layer of bedding material is spread evenly across the area.

The bedding layer should be high performance bedding (HPB). Once the first tier is installed completely, ½ inch holes are drilled through the Timbers and ½ inch rebar stakes are driven into the ground to prevent movement. Next the remaining tiers are built up ensuring that all joints are staggered. 10 inch structural lag screws are used to connect each new tier to the one below.

On larger walls deadmen’s or tie backs must be installed. These are t shaped supports which tie into the wall and are also anchored into the earth behind the wall to prevent the wall from shifting forward over time. Another key element is a drainage pipe which is installed behind the first course of the wall and outlets through the face of the wall. The pipes job is to relieve any hydrostatic pressure and protect the wall. 

Block Retaining Wall Construction 

Generally the excavation and preparation phases for both retaining wall types are identical. With a block wall, once the bedding layer is installed the first course of blocks will be installed taking precaution to ensure that each individual block is level on its own and with the blocks on either side of it. Remaining courses of block can be built up and usually the manufacturers have a built in key system which interlocks the blocks together as courses are built up. 

On larger walls geogrid will be needed to strengthen the wall and prevent movement over time. With block walks once the courses are all installed a layer of coping will be adhered to the blocks with concrete adhesive for a finished appearance. Lastly, both wall types follow the same principles for backfill behind the wall. The first 12 inches behind the wall should be filled with compacted ¾ clear stone to aid drainage. 

How Much Does a Wall Cost to Build?

Retaining Wall Cost 

As important as all of the other factors we will cover in this article are, most people are primarily concerned with one thing: How much will my new retaining wall cost? Let’s explore! 

For the purposes of this article we will use a wall that is 40 feet in length by 3.5 feet tall as our example for pricing.

Timber Retaining Wall Cost 

Timber retaining walls typically fall on the lower end of the spectrum with an average 140 square foot wall ranging from $14,000 - $16,000. 

Block Retaining Wall Cost 

Block retaining walls are typically slightly more expensive than timber walls. You can expect to pay between $25,000 - $32,000 for a similar sized wall.

Retaining Wall Durability 

Timber Retaining Wall 

Timber retaining walls are a durable retaining wall that can last upwards of 40+ years. That being said since they are made of wood they are prone to discolouration & rot over time. Some extra precautions which can be taken to slow down the aging process of a timber retaining wall would be applying a clear coat seal or stain every few years to preserve the wood. 

Block Retaining Wall 

Block retaining walls on the other hand are made of concrete so there is never a risk of rot or deterioration. Over time the sun may cause slight discolouration after multiple decades. Another benefit of block walls is since they are modular systems, minor repairs can be carried our seamlessly when needed. 

Conclusion 

In conclusion, if you are ready to have a new retaining wall built, both types discussed today are great options. Ultimately what is important is that you, the consumer, are making an informed decision that will best suit your needs. We hope that this article aids you in your decision.