Victorian Rear Extension, London

A homeowner in South London approached First4Estimating to provide a detailed cost estimate for a two-storey rear extension to their Victorian mid-terrace property. The project aimed to create a large open-plan kitchen-diner on the ground floor with an additional bedroom and en-suite bathroom above.

The client had architectural drawings prepared and wanted an independent estimate before approaching builders for quotes. They needed a clear understanding of likely costs to set a realistic budget and ensure they were not overpaying when comparing contractor tenders.

Victorian terraced properties present unique estimating challenges. The existing rear wall required significant structural steelwork to create the open-plan living space, and the party wall agreement added both cost and complexity to the programme.

The project also included underfloor heating throughout the ground floor, a full kitchen fit-out with bespoke joinery, and the need to match existing period features such as coving and skirting profiles. London labour rates and restricted site access typical of terraced streets further influenced the overall cost.

• Detailed cost estimate with full elemental breakdown covering substructure, superstructure, internal finishes, M&E services and external works
• Separate pricing for the structural steelwork package, enabling the client to obtain specialist quotes independently
• Provisional sums for the kitchen fit-out and underfloor heating, with allowances based on the client’s preferred specification level
• A clear cost summary document suitable for mortgage lender review and budget sign-off
• Guidance on which elements could be value-engineered to reduce costs without compromising quality

Armed with our detailed estimate, the client was able to confidently assess three builder quotes and identify that one contractor had significantly under-priced the steelwork element — a potential risk during the build. They appointed a mid-range contractor whose quote aligned closely with our estimate and completed the project within 2% of the original budget.