From £52,400
Starfish Properties is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote...
From £52,088
Dominic Payte - Design & Build is an established extension buildering business in W1. We come highly recommended and provide competitive quotes for...
From £51,944
Hestia Contractors Ltd are here to help customers who need an Extension Builder in W1. We offer a competitive rate to complete all your extension b...
From £52,040
Independent construction company we have wide range of experience, including newconstruction, renovation, design build and retail stores. We provid...
From £52,232
We are specialised in: demolition services, foundation services, property extension, general bricklaying, internal renovation and configuration, ca...
From £52,432
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £52,064
Experienced extension builder ready to quote for your work. Cornerstone is the best extension builder in W1. No obligation free quotes and many hap...
From £51,984
JK Doors is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote for extens...
From £52,288
Grand Phase Ltd is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote for...
From £52,312
Teammax LTD are here to help customers who need an Extension Builder in W1. We offer a competitive rate to complete all your extension buildering j...

Mansard loft conversions range from the cheapest installation of £51,944 (Hestia Contractors Ltd based in W1B) to the dearest of around £52,432 (Sehem Design based in W1F).
While these estimates give you a good idea how much you'll pay for a mansard loft conversion, the only way to get an accurate price is to get real quotes from real builders.
Get quotes to install a mansard loft conversion in W1 by posting a job with HaMuch and we'll send it to extension builders in W1.
Whether you’re looking to extend your kitchen with a side return extension or you want to convert your basement into a liveable space, read our cost guides to get an idea of how much each project costs before getting a more accurate quote from our database of reliable tradespeople.

Underpin a building - £17,678

Two storey extension - £88,268

Build a timber frame extension - £26,178

Build a swimming pool - £81,178

Single storey extension - £58,568

Side return extension - £43,507

Install an RSJ - £2,378

Outbuilding - £10,178

Build a Mansard loft conversion - £52,178

Loft conversion - £35,423

Build a kitchen extension - £42,178

Hip to gable loft conversion - £42,178

Granny annexe - £87,178

Garden office - £10,178

Convert a Garage - £16,178

Garage - £18,678

Build a flat roof extension - £22,178

Build a dormer loft conversion - £42,178

Concrete foundations - £6,428

Convert a bungalow loft - £29,178

Convert a basement - £39,507