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Home extension and addition cost estimator

Last update: 2023

How we built this tool?

We referenced more than 200 products and services to create the Billdr home extension and addition renovation cost estimator tool.

Our estimate pricing includes:

  • The material cost
  • The labor cost
  • General contractor’s profit (30%)
  • Project management fees (20%)


It is recommended to provide a budget contingency of around 10% to cover unknowns or additional requests during the work.


Your project cost may vary +/-20% from this estimate depending on many factors such as the room dimensions, contractor’s profit, number of subcontractors, location, schedule, project duration, materials selected and the current condition of the space (e.g. electrical, plumbing, etc.).

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