What Will My Project Really Cost?

If you’re planning a renovation or new build in areas like Wimbledon, Putney or Southfields, one of the hardest questions to answer is:
What’s the real cost of a project like this?

Most people start by thinking about the construction cost — what the builder will charge — but that’s only part of the picture. A successful project has many parts: design, approvals, surveys, VAT, finishes and a contingency. Here's how we help our clients break it down early on.

There are a lot of variables!

Even with a clear brief, no two projects cost the same. A lot comes down to the decisions made along the way.

Take something simple like a light switch. You could choose a £10 standard white plastic fitting, or a £100 bespoke bronze toggle. Apply that same range of choice across every element, from doors and taps to glazing and joinery and the variation in cost can be enormous.

That’s why we try to establish early on what matters most to you. Where do you want to invest? What are you happy to keep simple? Your priorities will shape the overall budget just as much as the square footage.

What Do We Mean by "Project Budget"?

Terminology around money in construction can get confusing. Here’s how we define the main terms we use:

• Project Budget
  The total amount you have available or are willing to spend on the entire project. This includes everything. Construction, design, VAT, fittings, surveys, and contingency.

• Contract Sum
  The value of the building works agreed with your main contractor. This covers what the builder will deliver under the construction contract, including labour, materials and preliminaries.

• Professional Fees
  Payments to your team of consultants. That might include architect, structural engineer, services engineer, party wall surveyor, planning or heritage consultant, and so on.

• Surveys & Planning Costs
  These include measured building surveys, drainage surveys, planning applications, lawful development certificates, and building control fees.

• Fixtures, Fittings & Equipment (FFE)
  These are the items you supply separately. Things like kitchens, appliances, sanitaryware, wardrobes, lighting, even curtain tracks. These are often excluded from the builder’s contract but essential to the finished project.

• Contingency
  An allowance for unexpected costs or changes during construction. Usually 5 to 10 percent of the contract sum, depending on the complexity and level of detail in the drawings.

• VAT
  Often overlooked, but usually 20 percent of most of the above unless the project is a VAT-exempt new build or charity use.

Example 1: Total Project Budget £500,000

We have chosen this figure as it reflects a common ‘mean’ figure which we’re given when we’re first approached by prospective clients.

Estimated breakdown:

• Main Construction Contract: £325,000 to £375,000

• Professional Fees (architecture, structural, M&E etc): £50,000 to £65,000

• Surveys & Consultants: £5,000 to £10,000

• Planning Fees & Building Control: £1,500 to £3,000

• Fixtures, Fittings & Equipment: £30,000 to £50,000

• Contingency: £25,000 to £40,000

• VAT: £80,000 to £90,000

Estimated main contractor sum: £325k to £375k

Example 2: Total Project Budget £250,000

A smaller extension or internal reconfiguration project.

• Main Construction Contract: £160,000 to £180,000

• Professional Fees: £25,000 to £30,000

• Other costs (surveys, planning, FFE, contingency, VAT): £40,000 to £60,000

Estimated contract sum: £160k to £180k

Example 3: Total Project Budget £1,000,000

Typically a full-house renovation or new-build with high-end finishes and bespoke detailing.

• Main Construction Contract: £650,000 to £750,000

• Professional Fees: £90,000 to £120,000

• Surveys, Consultants, Planning & Contingency: £150,000 to £180,000

Estimated contract sum: £650k to £750k

Why This Matters

Many clients come to us with a construction number in mind, but without a sense of the total project cost. By breaking it down early, we help you plan realistically, avoid stress, and get the most out of your budget.

We don’t inflate figures. But we do believe in building in proper allowances for everything that matters.

Need Help Planning Your Project Budget?

We’re always happy to offer early-stage advice, even before you’ve settled on a design.

Contact us for a short consultation or to discuss how we work or see our FAQs page for more information.