What is rough cost of a 3m dormer window and bathroom?

Hi Rod For a 3m dormer with a bathroom addition in an existing attic conversion especially within a conservation area £15,000 is likely too low, even as a ballpark. Key breakdown Structural dormer build (3m) £10K New bathroom installation £3-4K Design, drawings & building regs £1.5 - £2K Planning application (conservation area) £300–£1,000 Key Cost Drivers: Conservation area = likely bespoke materials, stricter planning compliance, and more oversight. Plumbing complexity (especially if drainage needs adapting). Structural modifications to accommodate dormer. Interior finishes (tiles, sanitaryware, flooring) – these can swing the cost a lot. You’d struggle to do it all in for £15k. You can lower the above cost estimate if bathroom is very basic and near existing plumbing and the dormer is prefab and requires minimal alteration. If your budget ceiling is £15k, it’s better to pause before applying for planning, as even a stripped-back version would likely overshoot. Happy to help, Charisma, Director at Nirmaya Estates Limited