Best Builders in Westminster, London

Builders in Westminster carry out extensions, loft conversions, refurbishments, kitchens, bathrooms and general repairs. Below you will find our selection of 5 builders in Westminster, with address, phone number, website and opening hours for each one, followed by practical advice on choosing the right builder, typical prices and answers to common questions.

5listed
1with phone number
2with website

5 Builders in Westminster

3Peter John and co

Address
101 Bell Street, London
Directions

4Yorkshire Building Society

Address
203 Strand, London
Directions

How to choose a builder in Westminster

  • Check planning permission and Building Regulations requirements before work starts.
  • Get at least three detailed, itemised quotes.
  • Look for membership of the Federation of Master Builders (FMB) or TrustMark.
  • Agree a written contract with stage payments; never pay the full amount upfront.

Checks and regulation: Most structural work needs Building Regulations approval; work on shared walls may need a Party Wall agreement.

How much does a builder cost in Westminster?

Single-storey rear extensions in London typically cost £2,500–£3,500 per m²; loft conversions £50,000–£90,000. Prices vary by area, time of day and the complexity of the job or service, so always ask for a written quote or check the latest price list before you book.

Builders across Westminster

Westminster covers neighbourhoods such as Mayfair, Soho, Marylebone, Covent Garden, Pimlico, Belgravia, St James's, Paddington (postcodes W1, W2, W9, NW8, SW1, WC2). The builders listed on this page are located in or around W10. Getting around is easy thanks to almost every Tube line, the Elizabeth line, and mainline stations at Victoria, Paddington, Charing Cross and Marylebone.

Frequently asked questions

Do I need planning permission for an extension in Westminster?

Many rear extensions fall under permitted development, but conservation areas and flats have stricter rules. Check with Westminster council.

How long does an extension take?

A single-storey rear extension usually takes 10–16 weeks once work starts.

What is a Party Wall agreement?

If you build on or near a shared wall, you must give your neighbours notice under the Party Wall etc. Act 1996.

Listings are compiled from public business information and OpenStreetMap (© OpenStreetMap contributors, ODbL). Details can change, so please confirm opening hours and prices with the business before visiting. Businesses can request corrections via our contact page. Last reviewed: September 2026.