Infill side-return extensions on Victorian and Edwardian terraces — opening up the kitchen and adding 8–15 m² of usable floor space.
Side return extensions in Southampton typically cost between £20,843 and £31,793 depending on size, specification and site conditions. A mid-range 12 m² project averages around £26,306.
Most side return extensions take between 6 and 16 weeks on site, depending on scope, structural complexity and planning requirements in South East England.
Many side return extensions fall under permitted development, but conservation areas, listed buildings and larger projects in Southampton can require a full planning application. Use the cost checker to see what applies to your address.
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Disclaimer: This is an industry-informed estimate for guidance only — not a fixed quote, valuation, survey or legal advice. Figures are based on UK regional averages and the details you provided. Site-specific factors (access, ground conditions, structural surprises, planning constraints) can materially change the cost. Always confirm with a site inspection, written quotes from qualified UK tradespeople, and supplier pricing before committing to work. Build Price IQ accepts no liability for decisions made on the basis of these estimates.