Waverton 2060 · North Sydney Council
Custom Home Builder in Waverton: Basements That Stay Dry
The garage goes under the house. The water will try to follow.
Street parking in Waverton is a daily contest, and many lots fall away toward Berry's Bay. So on a new custom home here, the garage often ends up in a basement cut into sandstone. Done well, it's the most useful room in the house. Done badly, it's a damp concrete box with a pump that fails during the one storm that matters.
Short answer
How do you keep a basement dry in a Waverton home?
Treat water as certain. Jointed sandstone weeps after rain, so walls get a drained cavity or tanking, subsoil drainage and a sump with two pumps, so one can fail safely. Driveways follow AS/NZS 2890.1 so cars don't scrape, with a grated drain at the bottom. Allow 13 to 18 weeks for a North Sydney DA; mid-spec homes run about $2,820 to $3,390 per m².
Written and reviewed by Oliver Alameri
Licensed builder, NSW Contractor Licence 487805C · Founder, Buildana
Fact-checked
How water gets into a basement
Sandstone looks solid. It isn't, quite. Water travels along its joints and bedding layers, so after heavy rain a basement wall cut into rock can weep for days, and runoff coming down the driveway adds a second source on top.
There are two broad ways to handle the walls. Tanking wraps the outside of the structure in a continuous waterproof membrane, so water never reaches the inside face. A drained cavity lets water reach an outer wall, then catches it in a cavity and drain behind an inner lining. Each suits different sites. The geotech report on rock and groundwater decides which.
What doesn't work is painting the inside of a concrete wall and hoping.
- Geotech report covering groundwater and rock joints
- Tanking or drained cavity, chosen for the site
- Membrane detailing at joints, corners and penetrations
- Subsoil drains behind retaining walls
Sandstone leaks along its joints. Design the basement as if it always will.
Pumps, and what happens when one fails
If water collected at the bottom of the driveway or behind the walls can't drain to the street by gravity, it has to be pumped. Which makes that pump one of the most important machines in the house.
So we design pump-out systems with two pumps that alternate and back each other up, a sump sized for a serious storm, and a high-water alarm. Council usually wants the design. A single cheap pump with no alarm is how basements flood.
Planning a basement in Waverton?
Share your survey plus a sketch of the house, however rough. I'll check the driveway levels, flag the waterproofing approach and give you a realistic excavation budget.
0476 300 300Driveways that don't scrape
The driveway into a basement has to drop steeply without the car's nose or tail hitting the concrete. AS/NZS 2890.1 sets limits on domestic driveway grades and requires gentler transitions at the top and bottom of steep sections.
The starting level is fixed by the council footpath at your boundary, and building a new vehicle crossing needs council approval. We check those levels in the survey before designing the basement floor height, because a basement 300mm too high or too low changes everything above it.
North Sydney's 1.28 loading on Rawlinsons puts mid-spec homes at about $2,820–$3,390/m². Excavation, waterproofing and pump systems are costed from the geotech, not guessed.
Basement garage checklist
Settle these before the basement level is drawn.
- 01
Geotech report on rock and groundwater
- 02
Choose tanking or drained cavity
- 03
Design dual pumps with an alarm
- 04
Confirm the footpath level at the boundary
- 05
Check driveway grades and transitions
- 06
Allow for council's vehicle crossing approval
Basements in Waverton
What's the difference between tanking and a drained cavity?
Tanking seals the outside of the structure with a waterproof membrane. A drained cavity collects water behind an inner lining and drains it away.
How steep can a residential driveway be?
AS/NZS 2890.1 sets maximum grades for domestic driveways with required transitions to stop cars scraping. The designer checks your specific levels.
Why does a basement need two pumps?
So one keeps working if the other fails. An alarm warns you before water rises into the garage.
Which council approves homes in Waverton?
North Sydney Council, postcode 2060. Heritage areas cover several pockets of the suburb.
Sources and references
Costs are from the Rawlinsons handbook with the local cost index applied; rules and timeframes are checked against the sources below.
A basement you'll never have to mop.
Custom homes in Waverton with basements designed around sandstone, groundwater and real driveway levels.