Build a complete cost structure
Separate land and financing costs from design, permits, factory contract, foundation, utilities, transport, crane, site finishing, taxes and landscaping.
Include temporary works, surveys, testing, insurance, storage and owner-supplied items that are often missing from early estimates.
Use realistic allowances
Rock excavation, utility extensions and finish upgrades may begin as allowances. Record the quantity or assumption behind each one and how actual cost will be calculated.
A low allowance does not reduce the eventual cost; it only delays recognition.
Carry contingency by risk
Early-stage projects need a larger contingency because land and design information is incomplete. Reduce uncertainty through surveys, soil work and written quotes rather than simply cutting the percentage.
Track committed, invoiced and forecast costs separately so the owner sees overruns before cash is required.
Apply this guide to a real project
For calculating the total modular-home project cost, create a dated project note tied to the destination address and current drawing revision. Identify the authority, designer, factory or contractor responsible for each unresolved item. Attach the written evidence for ‘Does the budget include every site and logistics category?’ and ‘Which figures are fixed prices and which are allowances?’ rather than recording a verbal assurance.
Before a deposit, production release, shipment or final payment, convert every open question into a named action with an owner and deadline. Keep superseded drawings and decisions in the record so later inspectors, lenders, insurers and future owners can understand why the completed house differs from an early sales plan.
Questions to resolve before proceeding
- Does the budget include every site and logistics category?
- Which figures are fixed prices and which are allowances?
- What taxes, duties and finance costs apply?
- Is contingency matched to unresolved risks?
Primary references to check
- Destination building department, approved plans and project contracts