How to fix a timber retaining wall?

NicoleDIY

I have a timber retaining wall along the side of my house on a steep block. The backyard has been levelled, and the retaining wall supports that cut. The timber posts have started to lean forward, which is now causing the fence to lean as well. I’m looking for advice on the best way to repair or rebuild the wall so it’s properly supported long-term. I was considering replacing it with Galintel steel posts and timber

   

sleepers, but I’m open to any recommendations that will future-proof the structure.

MitchellMc

Hi @NicoleDIY,

You’re essentially on the right track. With the leaning posts, the current wall will need to be disassembled and rebuilt using suitably sized posts at the correct spacing, with appropriately sized footings to safely retain the soil. Because this is quite a high retaining wall, it’s important to check with your local council about regulations and whether the wall needs to be engineered. Typically, retaining walls over 1 metre require certification and engineering to ensure they can safely hold back the soil.

Steel posts, such as Galintel, are an excellent option as they are much more durable than timber and won’t deteriorate over time. Timber sleepers can still work well, provided they are H4 treated for ground contact. Other options, like concrete, are also worth considering depending on the aesthetic and budget. 

Regardless of the materials chosen, the wall needs to be properly engineered to handle the load it is supporting. It’s likely the previous wall either didn’t have large enough footings or the posts weren’t adequate for the height and weight of the soil. Because removing and rebuilding a wall of this size carries a real risk of collapse, I would strongly recommend using a professional to repair or rebuild it. This will ensure it is safe and long-lasting. 

Please let me know if you have any questions.

Mitchell