Extension cost guide
How much does a house extension cost?
Published 20, 30 and 50 m² planning examples, the main budget drivers, and what to prepare before requesting a quote.
Practical advice from Ensign
Building guides for planning your project
Clear, evidence-backed help for planning an extension, renovation, new build or commercial project before you ask for a quote.
Start with your project
Choose the service pathway that matches your plans.
These links go directly to Ensign's building services and their matching project journeys.
Service pathway · Home extensions
Plan a home extension
Explore Ensign's extension service, completed work and the practical details that help shape a clear brief.
View home extensionsService pathway · Renovations
Prepare for a renovation
See how Ensign approaches refurbishment, layout changes and renovation projects with extension overlap.
View renovationsService pathway · New builds
Develop a new-build brief
Understand the service route for one-off homes, from early scope and drawings to build readiness.
View new buildsService pathway · Commercial building
Discuss commercial work
Review Ensign's commercial capability for property owners, landlords and project teams.
View commercial buildingHow Ensign guidance is checked
Useful information with a clear basis.
Reviewed by Ensign
Guidance is checked against Ensign's practical building experience before publication.
Evidence where it matters
Sources and the basis for factual claims are shown where they help you make a decision.
A visible review date
Every published guide shows when its information was last reviewed.
Need project-specific advice?