Rear Extension Structural Design £500.00 + VAT Loft Conversion Structural Design £650.00 + VAT Loft Conversion With outrigger structural design £770.00 + VAT Loft conversion and rear extension structural design £1,250.00 + VAT New basement reinforced concrete design £1,950.00 + VAT underpinned basement design£2,600.00 + VAT