Every service, one contract, in London.

It means one team designs your home and then builds it.

At NU that is architecture, interiors, cost and construction under one contract. The people who draw the home also price it and build it. Buildability, cost and design are decided together, not argued about later.

You get one point of accountability. If something needs sorting, there is one number to call.

A full renovation is priced after a free visit. The calculator splits every range by specification.

Floor area, scope and specification move the number most. Structural changes, access, services, kitchens, bathrooms and joinery all shift the total.

Use the build cost calculator for a first indication. Then send us the address. We will build a cost plan for your property.

As a whole project, a rear kitchen extension is typically £160,000 to £250,000. A side return is typically £140,000 to £220,000.

Size, foundations, structural openings, glazing, drainage and the kitchen itself drive the budget. Reworking the existing ground floor often costs as much attention as the new part. We price the new area and the existing rooms separately.

A new excavation is typically £500,000 to £900,000 as a whole project. Converting an existing lower ground floor is typically £180,000 to £300,000.

Excavation is only part of it. Engineering, temporary works, access, waterproofing, drainage and neighbour interfaces all need pricing. So does the fit-out that makes it a room.

We give you separate allowances for shell, services and finished accommodation.

A main dormer loft is typically £90,000 to £140,000 as a whole project. A mansard is typically £140,000 to £220,000.

Roof structure, stairs, headroom, roof form and bathrooms set the budget. Work to the floors below is part of the job.

The visible loft room is only part of the scope. Our cost plan includes the stair and the upgrades underneath it.

Allow for surveys, design, consultants, applications, construction, services, finishes and furniture. VAT and contingency sit on top of the build cost.

Professional fees and contingency sit outside the build cost. Our quantity surveyor prices both against your scope, not a fixed rule. VAT is 20 per cent and is treated separately.

Temporary accommodation, storage, removals, utilities and borrowing costs sit outside a contractor price. We give you one budget that shows what is in and what is out.

Because they are rarely pricing the same job.

Quotes assume different drawings, quantities, access, finishes, programme lengths and responsibilities. A lower total often hides missing work or a larger allowance.

Compare every tender against the same scope and the same exclusion schedule. We name our provisional sums, so you can see what is an allowance.

When the surveys, coordinated drawings, specification and responsibilities are settled.

We price twice. First a budget estimate from your brief and the property. Then a detailed cost plan, built line by line from the drawings.

That second price is the one you hold when you sign. Any remaining unknowns are named and allocated, never described as fixed.

Enough to cover what the survey cannot see until work starts.

The right figure depends on survey quality, building condition and scope. It also depends on how far the design has gone. A basement or a full strip-out carries different risk from a light refurbishment.

Our quantity surveyor sets it per project and explains what it is for. One percentage does not suit every home.

The contract sets out how work is valued and when you pay.

We value the work done, provide the evidence and issue a payment certificate. You get the payment schedule and a sample valuation before you sign.

A cash flow forecast helps you plan funding. It does not replace the agreed valuation process.

Ask for the actual documents, not a headline duration.

Product warranties, our defects obligations and insurance backed cover are three different protections. We tell you who issues each one, what it covers and what it excludes.

After handover the same team stays through the defects period, then aftercare.

It depends on the property, the proposed work and any existing restrictions.

Some work is permitted development. Eligibility has to be checked for your actual building. Conservation areas and listed buildings change the answer.

We review the address, the planning history and the drawings, then handle the application. Planning and building control are our job, not yours.

Work to shared walls or boundaries can engage the Party Wall etc. Act. So can certain excavations near a neighbouring building.

We review the scope against the adjoining structures before anything starts. Notices, Thames Water build over agreements and disputes are handled for you.

The surveyor needs the drawings and the adjoining owner details early. Leaving it late is what delays a start on site.

By engineering, temporary works, sequencing and monitoring, together.

We agree a monitoring plan with the engineer before excavation. Trigger levels are set, and each one has an action attached.

No responsible proposal promises zero movement because monitoring is installed. We have built London basements since 2010 and we say what the risk is.

Yes, and we do it often.

Send us the existing appointments and drawings. We need clear design responsibility, information standards, approval routes and coordination with construction.

Then we tell you what is still to be designed. We also tell you what we will price. Introduce us to the consultants early and it goes smoothly.

Yes, on request. We will sign an NDA before the first visit if you wish.

Nothing from your project is photographed for publication or shared without your written consent. Names and addresses are never disclosed. Many of our clients never appear anywhere.

Family office staff and advisers can brief us on the owner’s behalf. More on how we work in confidence is on our private clients page.