Last updated: 2026
All cost figures produced by this calculator are preliminary budget guidelines. They do not constitute a legally binding quotation, fixed-price offer, or formal contract.
Final construction pricing depends on formal architectural site surveys, structural engineering requirements, ground inspections, local authority planning permission, and current material market prices.
© 2026 Home Extension & Loft Conversion Estimator. All content, design elements, and calculation code are protected intellectual property.