Specify the finished room
Start with a room plan showing existing and proposed fixtures, door swing, drainage and service points. State whether the layout is retained or changed, what is removed and which fittings are supplied by the owner. A vanity price does not include every connection, and a tiling rate does not necessarily include removal, levelling or waterproofing.
This teaching project is a 2 m by 2.5 m bathroom in a detached Sydney house. It retains the main fixture positions and excludes structural changes, asbestos work and repairs outside the room. Those exclusions require investigation if suspected; they are not permission to ignore damage discovered during strip-out. An apartment needs a separate strata and building-class check before the same scope is ordered.
Measure finishes and whole boxes
For the quantity exercise, the selected design tiles all four walls to 2.4 m. Subtract one 0.8 m by 2 m door and assume no other openings. These are chosen finish dimensions, not mandatory Australian waterproofing heights. Recesses, niches, reveals and feature patterns must be measured separately in a real room.
| Measurement | Result |
|---|---|
| Net wall area: 9 m perimeter ×2.4 m −1.6 m² door | 20 |
| Floor area, m² | 5 |
| Finish area before purchase allowance, m² | 25 |
| With assumed 12% cutting/spare allowance, m² | 28 |
| Coverage per box, m² | 1.44 |
| Whole boxes required | 20 |
| Purchased area, m² | 28.80 |
| Assumed price per m² excluding GST, AUD | 55 |
| Tile supply excluding GST, AUD | 1 584 |
Twenty boxes provide 28.80 m²; buying only 28 m² is not possible under that packaging assumption. Confirm box coverage, batch, layout and returns before ordering. A spare-tile allowance is different from the membrane manufacturer’s coverage, the actual waterproofing extent and a project contingency.
Identify the concealed-work hold points
Ask the contractor to identify substrate repairs, floor falls and drainage, junctions, penetrations and the selected waterproofing system. Confirm who checks each stage before it is covered, and what photographs, test records and certificates the project requires. Check the contractor’s authorised scope using the NSW waterproofing category and trade-licensing information; an unrelated licence or a training certificate alone is not the complete contracting check.
The current Australian ARDEX WPM 002 technical sheet illustrates why substrate preparation, component compatibility, curing and testing depend on the actual system and site conditions. It is a product-specific source, not a recommendation to use that product. Have the relevant professional specify the applicable NCC, standards and manufacturer requirements. This article does not reproduce the paid AS 3740 standard, set universal coat thicknesses or prescribe a flood-test time.
Reconcile the complete quote
| Line | Amount |
|---|---|
| Strip-out and ordinary removal labour, excluding skip | 1 800 |
| Plumbing and fixture connections | 4 200 |
| Electrical work | 1 800 |
| Substrate and falls preparation | 2 500 |
| Waterproofing system and installation | 1 800 |
| Tiling labour | 3 500 |
| Tiles from quantity exercise | 1 584 |
| Sanitary fittings and vanity supply | 3 600 |
| Shower screen supply and fitting | 1 400 |
| Ventilation equipment and fitting | 600 |
| Skip and lawful ordinary-waste disposal | 800 |
| Commissioning and agreed records | 450 |
| Supplier subtotal excluding GST | 24 034 |
| Assumed10% GST | 2 403.40 |
| Supplier total including GST | 26 437.40 |
| Independent design/checking fee, final | 900 |
| Contingency: 10% of supplier total | 2 643.74 |
| Funding provision | 29 981.14 |
Assume all supplier lines above are taxable at 10%; the separate checking fee is already final. All installation and product boundaries are assigned once. The supplier’s commissioning record and the independent check are different tasks. The budget is invented, not a Sydney market quotation or a promise that hidden repairs fit inside the contingency.
Test a selection change before ordering
If the tile price rises by AUD 15 per purchased square metre excluding GST, the supply increase is 28.80×15= AUD 432 net, or AUD 475.20 including assumed GST. Keeping the contingency unchanged increases the provision to AUD 30,456.34. Price any different adhesive, extra cutting or laying labour separately before approving the new selection.
Ask for evidence that the revised product and installation remain suitable. Choosing a more expensive tile does not establish waterproofing quality. Record who accepts deliveries and checks damage; discovering a short batch after trades have been booked can add a return visit and delay the room’s availability.
Accept the room with evidence
- Check the agreed fixture models, operability and visible finish.
- Have drainage, ventilation and relevant services checked by the right trades.
- Collect concealed-work records before they disappear behind finishes.
- Record defects with locations, photographs and responsible parties.
- Confirm when the room can be used under the actual system instructions.
Keep the final account beside the scope, not just beside a completion photograph. A clean room does not prove the concealed work is correct. Record purchases, variations and payments in Reno Pro while retaining the contractor’s technical documents and any independent report.
Sources, date and scope
- Building Commission NSW — Waterproofing work
- ARDEX Australia — WPM 002 — Australian technical data sheet, June 2026
- Building Commission NSW — Categories and classes of building and trade work
Checked on 19 October 2026. Worked projects are in Sydney, NSW, unless stated otherwise. NSW rules are not national rules. All dollar amounts are Australian dollars (AUD); worked costs, quantities, margins and contingency percentages are invented teaching assumptions, not market prices, quotations or prescribed reserves. Each article describes a separate project. GST treatment is stated for the example; final amounts already include any applicable tax. Check the property, current approvals, insurance and contract with the appropriate professionals.