A retaining wall holds back saturated ground, so without waterproofing it slowly transmits that moisture straight through to the dry side. Goliath Coatings provides retaining wall waterproofing across Auckland, sealing the retained face and managing drainage so walls stay dry, sound and free of efflorescence.
What retaining wall waterproofing involves
Retaining wall waterproofing seals the soil-retaining face against constant ground moisture and applies a drainage layer that relieves water pressure behind the wall. Done at construction, it protects the concrete and any finishes on the inside face; done as remediation, it stops the damp, staining and salt deposits that appear once an untreated wall has been backfilled and loaded.
Systems and drainage
We apply liquid or sheet membranes to the retained face, add a dimpled drainage board and filter to carry water down to a drainage coil, and detail the base and any penetrations. Relieving the hydrostatic pressure is as important as the membrane itself — a sealed wall with nowhere for the water to go will still find a weakness eventually.
New walls and existing problems
We waterproof new retaining walls before backfill and remediate existing walls showing damp on the dry side. Where we cannot reach the retained face we treat the visible side with a negative-side system and improve drainage where access allows, matching the fix to what the site actually permits.
The products and systems we use
A retaining wall holds back saturated soil, so the priority is to waterproof the positive (earth-retaining) face and give water somewhere to go before pressure builds behind the wall. Before backfill we apply self-adhesive sheet and torch-on membranes — Bituthene 3000 and Preprufe, Sealco BondSEAL, and torch-on systems such as Sealco FlameSEAL, Allco Casali, Nuralite Nuraply 3PM or Viking Bituclad — then protect the membrane with a drainage cell or cavity drainage layer that relieves hydrostatic pressure and carries water to a subsoil drain. For existing walls we treat from the available face with cementitious tanking such as Mapei Mapelastic Foundation or crystalline Xypex.
Why choose Goliath Coatings
Retaining wall and below-ground waterproofing are a specialty. We waterproof the earth-retaining face and build in drainage so water is taken away before it can load up behind the wall — the detail that decides whether a wall stays dry or weeps for years. Free on-site assessment, one-business-day response, and the backing of 5-star Auckland reviews.
Retaining wall waterproofing FAQs
Q: My retaining wall is damp on the inside — can you fix it?
A: Yes — where the retained face is buried we apply a negative-side system to the visible face and improve drainage to relieve the water pressure behind it.
Q: Why does a retaining wall need drainage as well as membrane?
A: Drainage relieves the water pressure behind the wall so the membrane is not fighting constant hydrostatic load — together they keep the wall dry.
Q: Best time to waterproof a retaining wall?
A: At construction, before backfill, when the retained face is accessible — but we also remediate existing walls effectively.
Q: How do you stop a retaining wall from leaking?
A: By waterproofing the soil-side face before backfill and adding a drainage layer to relieve water pressure — typically a torch-on or self-adhesive membrane (Bituthene, Sealco, Nuraply) plus a drainage cell to a subsoil drain.
Q: What determines the cost?
A: The extent of the water ingress, whether the fix is internal or external tanking, and whether drainage needs upgrading. We diagnose the source on site — free — then quote the right system, not the most expensive one.
Q: Is the work guaranteed?
A: Yes — our workmanship is guaranteed and we install proven systems from leading suppliers. Goliath Coatings is fully insured, Tōtika accredited and Site Safe certified.