1. We underestimated electrical
Electrical rough-in came in over budget by roughly $5,000 once the upstairs upgrade scope was confirmed mid-build. The original quote covered the ground floor only and assumed the upstairs board was adequate. It wasn't. If we ran this again we'd have the upstairs board and tail-end load assessed before quoting the ground floor work.
2. We left window selection too late
Window lead times in Brisbane move. By the time we'd locked in glazing specs the prices had moved and the lead time pushed our weatherproofing target. Locking in a written window quote before slab is ready is a small piece of admin that prevents a multi-week delay.
3. We didn't pre-stage the engineering variations
A slab variation for deeper shale in one corner cost roughly $2,200 and added engineering time. We knew the geotech indicated variability. We should have priced a variation envelope into the original concrete quote rather than discovering it on pour day.
4. Sequencing: insulation before fit-off
On a build-under, insulation and plaster need to be signed off before the electrician and plumber come back for fit-off. We brought the trades in a day early and they sat. A better understanding of the inspection hold-point sequence would have saved that day.
5. The decision we wish we'd made differently
We chose polished concrete for the lower-level floor. It performs. But the slab finishing process required a longer cure window than we'd allowed, and it pushed downstream trades. See What we'd do differently for the longer list.
Where the figures came from
All of the figures referenced above are from the 2018-2020 Coorparoo project. Use them as a directional sense-check alongside your own current quotes. See the full breakdown.
