How to repair a Sandstone retaining wall?

[toni3]

Our 2-layered 20 mtr sandstone front retaining wall was badly constructed years ago but never had enough money to have it fixed. Money is still scarce but it now desperately needs repair because the top stones are falling one by one.

I have no idea what to do or who can fix it. Please help me 🥺

[MitchellMc]

Welcome to the Bunnings Workshop community @toni3. It's amazing to have you join us, and many thanks for your question about repairing a retaining wall.

It would be helpful if we could start with some images of the wall which show the issues you'd like to address. These will give our members a better understanding of the problems and help them provide useful solutions.

If you want to repair the capping stones, a D.I.Y. solution would be to use Selleys 415g Liquid Nails Landscape Stone Concrete Adhesive. Just clean the surfaces with a stiff bristle brush before applying glue to the underside of the capping stone. Put the stone back into position and push it down firmly to bed it in place.

I'll be looking forward to seeing some images and providing further assistance. Please let me know if you have questions.

Mitchell

[TheHandySqirrel]

Hi @toni3,

retaining walls can fail for various reasons, and photos would help sort out the main cause. Most fails I've seen (online) were due to lack of drainage or poor construction.

All retaining walls need to be constructed for the worst case: retaining water-soaked soil. Water adds a significant amount of weight. Also, you want to check if the existing wall has drainage – visible either via weep holes at the bottom or a small pipe coming out at the end (or also in the middle if the wall is long). If you don't find signs of drainage, that might be your main problem and you'd need to take down the wall, add drainage and rebuild.

Taller walls need to lean towards the hillside as well so that they improve their retaining capacity.

I'd contract a professional landscaper to have a look and give a quote. That might be at no cost to you and give you an indication of both the cost to fix and if you can do it yourself. Check with your local council from which height you need to consult a professional engineer for a compliant wall.