Interactive Tool
Adjust the inputs.
Change the fields below and the guidance will update instantly. This is a planning tool, so it is best used for early direction rather than final contract pricing.
Budget Planning
Extension Cost Estimator
Sense-check a realistic budget band for a rear, wraparound or double-storey extension before booking a site survey.
Build-rate
Build-rate guide
Specification
Specification uplift
Structural
Structural allowance
Human check
Use this output to sharpen a real survey request
Next Step
Turn the tool output into a real project conversation.
The calculator or checker gives you a clearer first position, but it cannot see access restrictions, underground conditions, drainage runs or final specification choices. Use the result to shape a better enquiry, then let the site visit handle the real-world detail.
- Take a few site photos and measurements before you call or send the enquiry.
- Include the output range or urgency level when you contact us so the brief is easier to review.
- If the issue involves drainage failure, structural movement or water ingress, escalate quickly rather than waiting on a perfect brief.