Granny Flat Site Costs, Soil & Slope Calculator
Explore fixed allowances for slope, soil, service distance and access. These illustrative scenarios do not establish prices, select foundations or assess site risk.
Estimate Hidden Site Variables
Use your geotechnical report and site information to explore the presets. Amounts are illustrative assumptions, not quotes or an engineering design.
Understanding Granny Flat Site Costs
What is the difference between a provisional sum and a fixed price?
A provisional sum is an allowance for work whose final cost is not yet fixed. Read how the contract adjusts it and ask which investigations could reduce uncertainty. Obtain advice on the contract terms rather than assuming every extra cost can be passed on without conditions.
Can I build on a sloping block without expensive concrete retaining walls?
Have the engineer compare suitable foundation options using the actual ground and site information. A suspended floor may be an option, but this tool cannot select it or predict a percentage saving over a slab.
What happens if our sewer connection requires an electrical macerator pump?
Ask the hydraulic practitioner and relevant authority to determine the approved drainage arrangement. If pumping is needed, obtain a quote covering equipment, installation, power, maintenance and approval requirements. We do not have a verified universal pump-installation price.
