Wandsworth Loft Conversions: Planning, Costs and Contractor Checks

A Wandsworth postcode does not determine whether a loft conversion is permitted or practical. The exact property type, roof, planning history and local controls must be checked before a layout or price is treated as reliable.

Start with the building

Measure the existing head height and inspect the roof structure. Then test where the new staircase can arrive without making the floor below awkward. A rear dormer can create useful full-height space, while a rooflight scheme may suit a roof that already has enough height. An L-shaped dormer or mansard changes more of the roof and needs a more detailed planning review.

If the property is a flat or maisonette, normal householder permitted-development rights do not apply in the same way. Freeholder consent and the lease can be as important as planning permission.

Check current Wandsworth guidance

Wandsworth Council explains that permitted development can be restricted for conservation areas and listed buildings, and that it does not apply to flats in the same way as houses. Article 4 directions may remove additional rights. Use the council's current planning-permission guidance and check the exact property rather than relying on a nearby conversion.

Even where planning permission is not required, building regulations still apply. Party Wall Act requirements, scaffolding licences and other site permissions may also be relevant.

Current budget guide

Bluebird's published loft ranges are:

• rooflight or Velux: £55,000–£75,000 ex VAT;
• rear dormer: £75,000–£110,000 ex VAT;
• L-shaped dormer: £90,000–£140,000 ex VAT;
• mansard: £100,000–£160,000+ ex VAT.

These figures are early guides. Professional and statutory fees, VAT, surveys and client-supplied items should be shown separately unless a written quote explicitly includes them. Try the cost calculator, then ask for a property-specific proposal.

Compare relevant completed projects

The Southfields loft conversion is the closest completed loft example currently published by Bluebird in SW18. Also review the Wandsworth side-return extension, Wandsworth new build and Earlsfield extension for local project delivery evidence. Each page states the recorded scope and programme; do not assume a different property will follow the same sequence.

Questions to ask before appointing a contractor

1. Which survey and drawings does the price use?
2. Is VAT included or excluded?
3. Are scaffolding, structural steel, insulation, windows and staircase included?
4. Who coordinates structural engineering and building control?
5. What planning, freeholder or party-wall assumptions are being made?
6. Which bathroom, heating, electrical and decorating allowances are included?
7. What is the payment schedule and how are variations approved?
8. Which completed project is genuinely comparable?

Bluebird is a Federation of Master Builders member and uses itemised quotes, no deposit upfront and weekly payments for completed work. See the full Wandsworth area guide or the Wandsworth loft-conversion service before requesting a callback or site visit.