By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.
Full waterproofing-and-drainage rebuild on the upper garage side wall at a Terranora property. Removed the concrete pathway and skipped it. Excavated below the footings and trenched down to the front of the property. Pressure cleaned the wall, patched defects with rapid-set, applied two coats of waterproofing, installed tunnel core protection, laid twin 100mm socked aggie pipes on geofabric, backfilled with 20mm blue metal drainage gravel, wrapped the geofabric back over to seal the drainage sock. Shaped the garden bed away from the property. Tied the drainage into the existing stormwater after CCTV check. Pressure cleaned site on completion.
What the customer called us for
Owner called us out to waterproof the right-hand side upper garage wall. Water was coming through the wall and they wanted the full stack done properly – excavation, waterproof, drainage, tie-in.
What we found when we got there
Standard side-wall water ingress problem. On a Terranora property with that kind of slope, groundwater pressure against a garage wall will find any defect in the wall and come through. The fix has to be the full stack: strip back to the wall, patch defects, waterproof, protect the waterproofing, drain the base of the wall, tie into the stormwater system. Skip any step and the fix fails.
Why we did it this way
Waterproofing alone fails because the waterproof membrane gets pressed against the wall by groundwater and eventually gets a pinhole, and then the leak returns. Drainage alone fails because some residual moisture always sits against the wall. The pair together is the standard. Three coats of waterproofing is the spec for anything below ground with water pressure. Tunnel core is the physical protection layer that keeps the gravel from damaging the membrane during backfill and over time. Twin aggie gives redundancy. Blue metal rather than recycled gravel keeps the drainage sock free of concrete dust.
What we did on site
- Removed the concrete pathway and skipped the material.
- Excavated below the footings and trenched down to the front of the property.
- Pressure cleaned the wall back to clean substrate.
- Patched defects and holes with rapid-set concrete.
- Applied two coats of waterproofing over two to three days depending on weather.
- Installed tunnel core protection against the wall.
- Laid geofabric along the trench and installed twin 100mm socked aggie pipes on the bottom of the trench.
- Backfilled with 20mm blue metal drainage gravel to the top of the trench.
- Ran the drainage down the hill to the existing stormwater.
- CCTV’d the existing stormwater to confirm it was in free-flowing condition before connecting.
- Wrapped the geofabric back over the top of the gravel to seal the drainage sock.
- Shaped the garden bed away from the property, ready for stone and pavers.
- Pressure cleaned the site and the driveway on completion.
The result
Garage side wall is now protected by three systems working together: waterproofing on the wall, tunnel core protection on the waterproofing, and a twin-aggie French drain at the base of the wall discharging into a verified stormwater line.
If you have the same issue
If you have a garage, basement, or any below-grade wall on a hillside Tweed coast or Gold Coast property and water is coming through, do not accept a waterproofing-only fix. The full stack is waterproofing plus drainage plus tie-in. Done once properly, it does not return. Done cheaply, it comes back worse. Call Matty on 0447 188 394 or request a quote.
Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).
Frequently asked
Why do you need tunnel core protection on the waterproofing?
The waterproofing membrane is a thin coating. When you backfill with gravel, sharp edges can scratch or puncture the membrane during compaction and over time. Tunnel core is a thick plastic dimpled sheet that sits against the waterproofing, protects it mechanically, and also creates a small air gap that lets residual moisture drain downward instead of pressing against the wall.
Why three coats of waterproofing not just one?
Each coat builds up thickness and covers any pinholes in the previous coat. Manufacturer spec for below-ground applications with hydrostatic pressure is three coats. One or two coats will fail at pinholes within a few years and you are back to square one.
Why CCTV the existing stormwater before connecting the new drainage?
If the receiving stormwater is compromised (silted, root-impacted, or broken) and you add a new drainage line to it, the first big rain will overload the compromised line. The new drainage then has nowhere to go and the water ends up against your wall again. CCTV first, fix any issues, then connect. Non-negotiable step on any full-stack job.
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