House Extension
in Windsor
Compare quotes from vetted Windsor extension builders for single-storey, double-storey and rear extensions. Transparent pricing from £19,500. Free, no-obligation quotes — results in 24 hours.
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How Much Do House Extension Cost in Windsor?
Real prices from completed projects in Windsor and the surrounding area. Costs vary by size, specification and access — use these as a starting guide, then get 3 free quotes for your specific project.
The most popular choice for UK terraces and semis. Adds a kitchen-diner or extra living space at ground level. Typically 3–5m deep, completed in 10–14 weeks.
Get quotes for this →Maximum space gain in a single build — adds a ground-floor room and a bedroom above. Strong ROI in most UK property markets. Requires full planning permission.
Get quotes for this →Ideal for terraced homes with a narrow side alley. Transforms a cramped kitchen into a full-width open-plan space. Often combined with a rear extension.
Get quotes for this →Costs depend on size, spec and access. The best way to know your exact price is to compare 3 quotes from vetted local specialists.
Get free quotes →Windsor pricing note: South East England prices run 15–25% above the national average, particularly in Surrey, Kent and areas within commuter distance of London. Strong demand and limited contractor availability in peak season push costs higher. Prices shown are indicative ranges for Windsor and South East. Always get at least 3 written quotes before committing to any builder.
House Extension Specialists Who Know Windsor
Windsor has a thriving home improvement market driven by a strong local economy and a mix of Victorian terraces, post-war housing and contemporary developments. Finding the right builder is key to any successful project.
Every builder in our Windsor network is thoroughly vetted before joining BestBuilders. We verify insurance cover, check trade memberships with bodies such as the FMB and CIOB, and require a minimum of five real customer reviews.
From a small bathroom refurbishment to a major double-storey extension, our vetted Windsor builders cover the full range of residential projects. Request your free quotes today and compare options before making any decisions.
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What Windsor Homeowners Say About Our House Extension Specialists
Full-width rear extension on our cottage in Windsor. 32m² extension with full-height glazing, underfloor heating throughout the new floor area. Total project £84000 across 15 weeks. Building control sign-off on the first inspection.
Compared four extension builders through BestBuilders for the Windsor job. Mid-tier quote of £61600 won on the proper cavity tray detail. Internal openings cut on a Saturday so the rest of the family was barely disturbed. £72000 fitted, 12-week site programme. Lived in throughout - dust kept to the construction zone, never the rest of the house.
Nine months in and the rooflight has not leaked a drop, even in heavy rain. Builder we found via BestBuilders in Windsor suggested moving the boiler to the new utility room - much quieter at night now. Total £75000. Estate agent valued the work at +£90k.
House Extension in Windsor — FAQs
Plan Your house extension Project in Windsor
Whether you're researching costs, checking planning rules, or comparing approaches before you commit, our editorial team has produced these guides to help Windsor homeowners make informed decisions about their house extension project.
House Extension Cost Guide
Detailed UK price ranges, regional adjustments and worked examples for house extension projects.
Read House Extension Cost Guide →All House Extension Specialists
Browse our nationwide network of vetted house extension contractors covering all 519 UK towns.
Browse House Extension Specialists →All Cost Guides
Compare prices across extensions, lofts, kitchens, bathrooms, roofing, driveways and solar projects.
View All Cost Guides →Planning your house extension project? Read these guides:
Planning Your House Extension in Windsor
Before you compare quotes, it's worth understanding the full UK price picture for house extension and how Windsor sits within it. The guides below cover average costs, what affects your quote, and how to choose a builder you can trust.
UK House Extension Cost Guide
Full price ranges, worked examples and the factors that move your quote — drawn from real project data across 519 UK towns.
Read the house extension cost guide →House Extension Across the UK
Browse house extension services nationwide, see what's typical in your region, and request quotes from any UK location.
Visit the UK house extension hub →Planning Permission for House Extension in Windsor
Find out whether your house extension needs planning permission in Windsor, what Permitted Development limits apply, and how rules differ in conservation areas, Article 4 zones, and listed-building settings.
Read the house extension planning rules →More homeowner resources: all UK building guides, cost guides, planning permission, comparisons, how-to guides and industry insights.