Loft Conversion Preparation Checklist

Most loft conversions fall under permitted development if they meet specific volume and design criteria. Confirm with your local authority before assuming.

In NW London, many properties are in conservation areas. Dormer windows and roof alterations may need full planning permission.

If any structural work affects a shared wall or is within 3m of a neighbour's foundation. Notices must be served 2 months before work starts.

Loft conversions always require Building Regulations approval. This should be submitted by the builder or architect before work starts.

Every loft conversion requires structural engineering calculations — for the new floor beams, roof modifications, and any internal steel work.

Everything out of the loft. The builders need clear access and all items will be damaged during the conversion. Do not leave anything valuable.

The new stair to the loft typically takes a bedroom cupboard or landing space. Confirm the position and the impact on the room below before work starts.

The new loft room needs heating and possibly hot water. Confirm with the heating engineer whether the existing system can extend and what is needed.

Lighting, sockets, TV aerial, data points. All wiring is easier to route during the build than afterwards.

Loft conversions are noisy and dusty. The roof will be open for days during dormer construction. Plan for dust protection of rooms below.

Typical sequence: scaffolding (1 day) → roof opening and dormer frame (1–2 weeks) → roofing and weathering (1 week) → first fix timber and structural work (1–2 weeks) → first fix M&E (1 week) → insulation and plasterboard (1–2 weeks) → second fix and decoration (2–3 weeks) → staircase (1–2 days) → snagging.

Inspections happen at key stages. Failing an inspection stops work. A good builder manages inspection timing — confirm they have submitted and booked.

Lofts frequently reveal unexpected structural conditions — oversized purlins, unusual configurations. A 15–20% cost and time contingency is prudent.