Disclaimer
Extension costs vary by project, property, and local conditions.
This page explains the limits of the calculator and guide content on Extension Cost Calculator UK.
General information only
The content on this site is general information for UK homeowners researching house extensions and related costs. It is not tailored advice for your specific property, budget, planning position, or construction contract.
Calculator outputs are early budget ranges only. They should not be treated as formal quotations, guaranteed build prices, or professional cost assessments.
No professional substitute
Nothing on this site replaces advice from qualified architects, structural engineers, planning consultants, solicitors, financial advisers, or contractors. You should consult suitable professionals before making decisions about design, planning applications, building regulations, structural work, party wall matters, finance, insurance, or contractor appointments.
Always obtain detailed written quotes and confirm exactly what is included before committing to any project scope or contract.
Limitation of liability
To the fullest extent permitted by applicable law, Extension Cost Calculator UK accepts no responsibility or liability for any loss, damage, or expense — direct, indirect, or consequential — arising from use of or reliance on the content, calculator outputs, or guidance on this site.
This includes but is not limited to losses relating to construction costs, planning decisions, contractor selection, financial commitments, or project outcomes.
Accuracy and changes
We make reasonable efforts to keep content and cost data up to date, but construction costs, planning fees, and regulations can change. We cannot guarantee that information on the site reflects current market conditions at the time you read it.
We reserve the right to update or remove any content at any time without notice. For full terms of use, see our Terms and Conditions.