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.
Large drainage job on a hillside property in Tweed Heads. Groundwater was rotting out the timber support posts under the main house. Used vacuum excavation to cut drainage channels under the property where the mechanical excavator could not reach, plus a mechanical crew on the external work. Waterproofed the back wall of the house, ran drainage down the side of the property to a second dwelling (garage), waterproofed that too, discharged everything to the street.
What the customer called us for
Owner called us out for serious drainage issues at a hillside property in Tweed Heads. Groundwater was coming through the ground against the back wall of the house and rotting the timber posts holding up the foundations.
What we found when we got there
Two-dwelling hillside property. Main house at the top had groundwater pressure against the back wall, with no existing drainage. Timber support posts were visibly rotting. Access underneath the house was too tight for a mechanical excavator, so we needed vacuum excavation to cut the drainage channels under the structure.
Why we did it this way
Groundwater against a back wall on a slope is a pressure problem, not a surface problem. A French drain against the wall, at the right depth, takes the pressure off the foundations and gives the water a planned path away. Waterproofing the wall adds a second line of defence. Vacuum excavation lets us work in tight spaces under structures without risking the footings, which is exactly what a hillside build needs.
What we did on site
- Set up on site with both mechanical excavation and vacuum excavation crews.
- Used vacuum excavation to cut drainage channels under the main house.
- Diverted groundwater around the structure to stop the timber-post rot.
- Waterproofed the back wall of the main house.
- Installed drainage against the newly waterproofed wall.
- Ran drainage down the side of the property to the second dwelling (garage).
- Waterproofed the garage wall.
- Installed new drainage against the garage wall.
- Discharged the full system to the street at the front of the property.
- Backfilled and tidied up on completion.
The result
Groundwater now diverted around both structures. Back wall of the main house and the garage wall both waterproofed and drained. No more pressure against the foundations. Everything discharges to the street.
If you have the same issue
If you own a hillside property on the Northern Rivers or the Gold Coast and water is coming through walls, pooling under the house, or rotting timber posts, that is not a leaking roof problem. That is a groundwater drainage problem. Treat it from the outside with a proper wall drain and waterproof system. 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
What is vacuum excavation?
A truck-mounted vacuum system that uses high-pressure water or air to break up the ground and then sucks the spoil out through a hose. It lets us dig in tight spaces, around existing services, and under structures without the risk of a mechanical excavator hitting something.
Why waterproof the wall AND run drainage?
Belt and braces. Drainage takes the bulk water pressure off the wall so it is not sitting in groundwater all the time. Waterproofing stops the residual moisture that still sits against the wall from wicking through. One without the other eventually fails.
Can this be done without digging up the yard?
On a flat site, sometimes. On a hillside with groundwater pressure, no. The water is in the ground, so the fix is in the ground. Vacuum excavation keeps the surface disturbance to a minimum but the drainage still has to go where the water is.
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