Timber Retaining Wall Repairs and Replacement
Timber Retaining Wall Repairs and Replacement
About Timber Retaining Walls Needing Repair or Replacement
We all know that timber retaining walls don't last forever. As you drive around Brisbane and Gold Coast especially the suburbs that were built in the 60s to the 80s you will see leaning fences and retaining walls.
Timber retaining walls rot, lean, crack, or fail over time - often without warning, and often after some rainfall.
We specialise in replacing timber retaining walls with concrete sleeper retaining walls.
These retaining walls can be repaired, but it's generally costly to do so, and you are just masking the underlying problem, as the wall will then fail somewhere else.
What We Do
We undertake a full wall removal and rebuild, which includes removing the old wall, removing the backfill behind the wall, and replacing with a new concrete sleeper retaining wall. A lot of the older timber retaining walls are built without adequate drainage, so this we ensure the new retaining wall has proper ag-pipe, gravel backfill, and Geofabric to ensure long lasting drainage.
Why Do Timber Retaining Walls Fail?
Timber rectangles don't last forever. Overtime in the Queensland whether the timber will rot, lean, crack or fail completely. If you look closely at the base of the timber post, you will likely notice that it is either beginning to rot or severely rotted. This rotting compromises the stability and strength of the post which slowly starts to lean and eventually fails.
Furthermore, upon inspection of a lot of the retaining walls that we repair we noticed two other major issues;
- The footings are not deep enough,
- The drainage installed is not adequate - either the drainage pipe is too small, the drainage gravel is not sufficient, or there was no geographic installed to separate the soil from the drainage gravel.
Engineering Advice for Timber Retaining Walls
Most of the time, it's extremely obvious that the timber retaining wall is failing. This can be seen by;
- Wall is leaning
- Timber is rotting or crumbling
- Water pooling behind the wall
- Cracks or movement between posts
- Fence above is starting to tilt
Do you need engineering advice for your timber retaining wall? We can offer engineering (see here) for retaining walls, including assessments of current timber retaining walls, though most of the time this money can be better spent on the wall itself.
How Long Do Timber Retaining Walls Last
You can expect around 10-20 years for timber retaining walls, depending on a variety of factors. Some solid hardwood retaining walls can last 25-30 years, and some larger timber retaining walls can last up to 50 years, but this is uncommon and often will experience leaning well before that.
Can You Repair My Timber Wall Instead of Replacing It
Yes - but. Most of the time when we discuss the options with the owner, they opt for replacement. If it's obvious that the rest of the retaining wall is likely to fail soon after, then it's not worth spending money on repairs. If there is just one or two posts that might need repairing, but the rest of the wall has plenty of life left, then perhaps it's a good option. These options can be discussed during an enquiry or phone call.
For general retaining wall regulations, see QLD Building Guidelines.