Additional details for the site, such as a geotechnical (geotech) report and land survey are typically required to determine a more accurate build cost.
Additionally, due to the shortage of skilled, licensed builders and the ever increasing costs of materials, build costs are slowly rising.
So, for a ground floor, small single level extension, the indicative build cost at the lowest end of these estimates ($2,500/m2) for a 36m2 extension would be roughly $90,000 ex GST. This is your starting point and dose not include a bathroom, kitchen, architect and engineers fee, contingency fund and council fees.
However, you will also need to add the following costs:
- Professional fees. For example,
- Architect fees for preliminary and building consent drawings. For a simple home extension (up to 100m2) project the fee would be in the region of $8,500. This fee is typically dictated by the complexity of the project.
- Geotech fee; budget for $1000.
- Survey fee; for a topographical survey budget for $3,500.
- Plan a contingency fund. Renovations have a habit of revealing hidden surprises. Allow at least 15% of your project value, for overruns, unforeseen costs or changes to the plan.
- Council building consent fees. This fee is calculated on the project value. Use this link to check them out.
- Add GST to your final build cost.
Until the plans are completed by the architect, you will not know the exact cost of the home extension. When plans are completed, a more accurate quote can be presented to the homeowner.
TIP: When you receive a build cost quote, check if the following is included:
- Building warranty cost. This may be part of the preliminary and general (P&G) costs.
- Council costs.