Extensions and loft conversions
Rear, side-return and loft schemes designed and built by one team, from the first survey to the final snag.
EnquireDesign and build, central London
From a loft extension in Park Royal to a 17 unit scheme in Knightsbridge.
Design and construction under one contract.
What we do
Every stage of the build, under one contract
Full refurbishment
Whole-house refurbishment with services renewed throughout and no scarring to the existing fabric.
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Basement excavation
New lower-ground levels formed beneath the existing footprint, with underpinning and structural work carried out in-house.
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Listed and heritage work
Grade II townhouses and conservation areas, with listed building consent secured and administered by us.
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Structural alterations
Steel-framed openings, removals and reconfiguration, priced and engineered before a wall is touched.
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Multi-unit developments
Multi-unit and mixed-use schemes delivered to a fixed price from RIBA Stage 2.
EnquireReady for a fixed price from Stage 2?
Get a quoteWho we build for
The same standard at every scale
Private residences
One team from the first survey to the final snag, so there is nobody left to blame and nothing left to coordinate.
- Extensions and loft conversions
- Full refurbishment
- Basement excavation
- Structural alterations
- Planning and building regulations
- Party wall coordination
Listed and heritage
Grade II townhouses, conservation areas and facade retention. The work that needs a conservation officer on side and a contractor who has done it before.
- Listed building consent and liaison
- Facade retention and restoration
- Structural work to period fabric
- Specialist joinery and stonework
- Services integrated without scarring
- Lime, lath and traditional finishes
Developments
Multi-unit schemes delivered to a fixed price from RIBA Stage 2, with a programme that holds from contract to handover.
- Multi-unit residential
- Mixed-use schemes
- Programme and cost management
- Phased handover and aftercare
- Framework agreements
How it works
Four stages, one contract, one team
01
Survey
Before any drawing begins, we walk the building with our structural engineer and our quantity surveyor. What we find determines what we promise.
02
Drawings
Design and technical drawings are produced in-house, reviewed against budget at each RIBA stage. Nothing is drawn that cannot be built at the agreed price.
03
Fixed price
We issue a single fixed-price contract at RIBA Stage 2. No provisional sums, no designer risk. The number you sign is the number you pay.
04
Build
Our site team is employed directly, not subcontracted for each job. The same people who priced the work build it. That is the point.
Belgravia SW1, completed 2025
Recent work
Recently completed projects
Prime residence, Belgravia
Chester Square
A whole-house refurbishment behind the retained facade of a stucco-fronted Grade II townhouse, with a new lower-ground level formed beneath the existing footprint.
Design and construction were held under a single fixed-price contract from RIBA Stage 2, with a conservation officer engaged from the first survey through to completion.
Area
520 m²
Programme
82 weeks
Architect
Malux Design
Completed
2025
Testimonials
What our clients say
They priced what they drew and held it. The number we signed at the start was the number we paid at the end.
SW11 / Rear extension
One team from survey to handover meant there was never anyone to chase. The listed consent was handled entirely by them.
W8 / Listed refurbishment
The programme held to the week. We had a confirmed budget before planning was even granted.
N1 / Loft conversion
About Malux
Design and construction, held under one roof
One contract, one programme, one cost plan, one team accountable from survey to handover. Design and build removes the gap between what an architect draws and what a contractor prices. That gap is where most projects lose their ambition.
Under a traditional contract the architect draws, the contractor prices, and the difference between the two becomes a variation. Variations become claims, and claims are what turn a nine month programme into fourteen.
We price what we draw. When a detail changes the cost moves with it that week, in the same document. There is nobody to argue with, because there is nobody else.
Practice
41 people
Founded
2009
Listed work
RIBA Stage 2 onwards
Common questions
The questions we are asked on every job
Yes. We prepare and submit both planning applications and building regulations packages in-house, and manage them through to approval. You deal with one team throughout, not a chain of separate consultants.
Most single-storey extensions run between sixteen and twenty-four weeks on site, depending on ground conditions and specification. We confirm a programme with your fixed price, so the end date is agreed before we start.
We issue a single fixed-price contract at RIBA Stage 2, once the design is resolved and costed. There are no provisional sums and no designer risk carried into the build.
Yes. Design and technical drawings are produced by our own team and reviewed against budget at each stage. Nothing is drawn that cannot be built at the agreed price.
Payments are made against a schedule of monthly valuations tied to work completed on site. Each valuation is measured and agreed before it is invoiced.
Yes. We coordinate party wall notices and liaise with adjoining owners and their surveyors as part of the programme, so the process runs alongside the works rather than delaying them.
All work is covered by a defects period after completion, with structural elements backed by the relevant warranties. We remain the single point of contact for any aftercare.
We work across central and greater London, from single residences to multi-unit schemes. If you are unsure whether your project falls within our area, send us the postcode and we will confirm.
Ready to start your project?
Send us the drawings, or just the postcode and a sentence about the project.
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