How to Choose a Retaining Wall Contractor

Written By Jonathon Plummer

Not all retaining wall contractors are created equal—some are reliable and skilled, while others may not meet your expectations. To avoid costly mistakes, use this 10-point checklist when gathering quotes for your retaining wall project:

10-Point Checklist

  1. Engineering – Any wall over 1m high or within 1.5m of a load-bearing structure must be designed by an engineer. Ensure your contractor understands and follows these regulations. Check out our engineering guide for more details.

  2. Deposit Requirements – According to QBCC regulations, any residential project over $3,300 requires a contract. Deposit rules are as follows:

    • Projects under $20,000: Maximum deposit of 10%

    • Projects over $20,000: Maximum deposit of 5%

  3. QBCC Insurance – QBCC Home Warranty Insurance is mandatory and based on the project’s value. The contractor collects the fee from you and arranges the policy on your behalf.

  4. Sleeper Materials – If a contractor suggests timber as an alternative to concrete, reconsider their expertise. Concrete sleepers offer superior durability and a lifespan of 30+ years. While timber may be suitable for small garden beds, concrete is the best choice for long-term stability.

  5. Drainage – A 100mm socked agg drainage pipe must be installed behind the wall to direct water to the nearest stormwater connection (if engineered). This prevents water from seeping through the wall. Ensure this is included in the quote.

  6. Geo-Fabric – This material prevents soil from washing onto the retaining wall, reducing staining and erosion. Confirm its inclusion in the project.

  7. Free-Draining Aggregate – A layer of 20-40mm drainage gravel should be placed behind the wall, reaching at least one sleeper height below the wall’s top and wrapped in geo-fabric. Proper drainage is critical to prevent structural failure due to water pressure.

  8. Rock and Ground Conditions – In-ground obstructions can impact costs. Ensure the contract specifies who is responsible for unforeseen obstacles and any associated costs.

  9. Reviews – Research the contractor’s online reviews. If they have few reviews or a rating below four stars, proceed with caution.

  10. Licensing – Request proof of the contractor’s license and verify it on the QBCC website to ensure they are qualified to perform the work.

Checking all 10 points before hiring a contractor can save you from expensive mistakes and structural issues down the line.

Don’t take chances—see an example of a collapsed wall below!

Here at Pro Trade Solutions, all of our walls are built to engineers specifications, and we have heaps of 5 star reviews! Ask your estimator for more information.

Don’t get it wrong! Go with the experts! Choose Pro Trade Solutions :) We look forward to working with you on your next project!

Jonathon Plummer