What happens at enquiry and survey stage?
An initial enquiry (often via our quote tool) is followed by a full survey to confirm head height, roof structure and staircase options for your specific property.
Our quote tool gives an early, honest read on suitability based on your roof and property type. A full survey follows to confirm exactly what's achievable — head height, roof structure, staircase position and any obvious constraints like water tanks or chimney breasts. This is the stage where a realistic project-specific programme starts to take shape.
What happens during design and quote?
Design finalises the layout, conversion type and specification, informing a firm quote before any planning or Building Regulations applications are submitted.
With the survey complete, design work settles the conversion type, room layout, staircase position and any add-ons like an en-suite. This feeds into a firm quote, so cost is understood before committing to the planning and Building Regulations stages that follow.
When is planning permission needed, and how long does it add?
Many conversions proceed under permitted development, but conservation areas, Article 4 Directions or a mansard-style design usually need a full application, adding weeks to months before construction can start.
See our planning permission guide for the specific rules. Where a full application is needed, this stage runs in parallel with finalising Building Regulations drawings, so it doesn't necessarily double the time added to the overall programme.
What happens with Building Regulations and the party wall process?
Building Regulations approval and, where a shared wall is affected, Party Wall Act notices are handled before or alongside the start of construction.
Building Regulations approval is separate from planning permission and applies to nearly every conversion — see our Building Regulations guide. Where the project affects a wall shared with a neighbour, formal Party Wall Act notice is served in good time before work starts, since neighbours are entitled to a response period before construction can proceed on a shared structure.
How long does the actual build take?
Build time ranges from around 4–6 weeks for a Velux conversion to 12–16 weeks for a mansard, covering structural work, the roof, insulation, staircase and first-fix services.
See our full build-time guide for a breakdown by conversion type. This is the most visible and disruptive stage, particularly during the roof-open period, but most homeowners stay in the house throughout.
What happens at fit-out and sign-off?
Fit-out covers flooring, decoration and fittings, and the project finishes with Building Control inspection and a completion certificate confirming the work meets all applicable regulations.
Once the structural and first-fix work is done, fit-out covers plastering, flooring, decoration and any bathroom or kitchen fittings. A final Building Control inspection checks the finished work against Building Regulations before issuing the completion certificate — the formal record that the conversion was done properly.