You've got a house, an idea, and no idea what the professional fees come to. Straight answer: on a domestic project our fee is a percentage of the construction cost, and that percentage sits between 5.5% and 7%.
The larger the project, the lower the percentage. A modest extension sits near the top of that range. A whole-house renovation or a new build sits near the bottom. That's the short answer, and it's at the top of the page because it's what you came for.
what the percentage is a percentage of _
This is where most people get caught out. The percentage is applied to the construction cost, meaning the money that goes to the builder to build the work. Not what your house is worth. Not your total project budget.
It also sits outside VAT, statutory application fees and the fees of any other consultants. So if a builder's price for your extension is £60,000, the fee is calculated on £60,000, whether the house it's attached to is worth £300,000 or £900,000.
So the fee scales with the thing being built, not with your postcode.
why nobody can quote you off a phone call _
We can give you a range on the phone. We can't give you a fee. The number depends almost entirely on things that only become legible when you're standing on the site.
How the ground slopes. Where the light comes from at four on a November afternoon. How close the neighbours sit, and which of their windows look at you. Whether the house is listed or sits in a conservation area, and how much of the existing fabric has to be worked with rather than cut into. Whether there's planning history on the site that shapes what the council expects to see.
Two extensions of identical floor area, a mile apart, can carry very different amounts of work. So we visit the site before we quote. It costs you nothing, and it's the only way the fee becomes a real number rather than a guess with a decimal point in it.
riba work stages, explained like a human _
Architects talk in RIBA work stages. It's useful shorthand between professionals and opaque to everyone else, so here's what actually happens and roughly where the fee sits. Our process page walks through the same journey in more detail.
stages 1–2 · brief, surveys and concept design · about 30%
We work out what you actually want, which is rarely what you first said. The house gets measured. The site gets read for orientation, levels and neighbours. Then we draw options: plans, sections, sketches you can argue with. You end up with a scheme you recognise as yours.
stage 3 · developed design and planning · about 20%
The chosen scheme gets resolved properly, with the massing settled, the fenestration set and the materials chosen, then prepared for the planning application with the drawings and supporting information the council needs. This is where the design stops being a good idea and becomes a proposal someone has to decide on.
stage 4 · technical design and building control · about 39%
The biggest share, which surprises people who assume the creative work at the start is where the money goes. Stage 4 is where the drawings that actually get built get made: junctions, thresholds, insulation lines, waterproofing, ironmongery, the structural engineer's work coordinated into ours, everything a building inspector needs, and everything a builder needs in order to price the same project as every other builder.
A thin set of drawings isn't cheaper. It just moves the cost. Decisions left off the page get made on site, fast, by someone else, and they get invoiced.
stages 5–6 · construction and handover · about 11%
Site visits, answering the questions a build throws up, checking that what's going up is what was drawn, and closing the project out. Where we're administering the building contract, it's also where changes get costed and agreed before they happen rather than discovered later.
percentage or fixed fee _
Both are normal and we do both, and which one fits only becomes obvious once we've seen the site and understood the brief.
A fixed fee suits a project with a clear, settled scope. Everyone can see what's being priced, and the number doesn't move.
A percentage suits a project still finding its shape. The fee moves with the project instead of being renegotiated every time the brief develops, which on an evolving job is the calmer arrangement for both sides.
Neither is cheaper by nature. Anyone who says otherwise is describing their own preference, not your project.
what pushes a fee up _
- Listed status. More scrutiny, more evidence, more careful detailing against existing fabric.
- Conservation areas. Materiality, proportion and impact on the street all have to be argued, not assumed.
- Sloping or tight sites. Levels, retaining, access and overlooking all add design and coordination work.
- Party wall situations. Building up to or off a shared wall brings process as well as design.
- Planning history on the site. A previous refusal changes how an application has to be made.
- Wanting several options explored. Legitimate, and often worth paying for, but it's more drawing.
what brings a fee down _
- A clear brief. Knowing what you want the house to do, even loosely, removes whole rounds of drawing.
- A straightforward site. Level ground, room to work, no designations.
- Deciding things once. The most expensive habit in a domestic project is reopening a decision after the drawings have moved past it.
what is not in an architect's fee _
Real costs, all of them, and they sit alongside our fee rather than inside it.
- Planning application and building regulations fees, which are paid to the council.
- A structural engineer, on almost any project that removes a wall or spans an opening.
- A quantity surveyor, on larger projects where the budget needs its own specialist.
- A planning consultant, where a site or a policy makes one worthwhile.
- A party wall surveyor, where the work engages a shared wall.
- The build itself, which is by a wide margin the largest number in the project.
We'll tell you which ones your project is likely to need before you commit to anything, not halfway through.
a worked example _
Round numbers, and illustrative only. Take a single-storey extension of roughly 30 square metres. Architect-designed work of this kind is currently landing at somewhere between £2,200 and £2,800 per square metre of construction cost, excluding VAT. Call it £2,500 for the sake of the example, and the build is in the region of £75,000.
At the middle of our fee range, the architectural fee on that project lands somewhere around £4,500 to £4,900, covering the work from brief through to construction.
Two things about that rate. It excludes VAT, which is charged at 20% on domestic work and often gets left out of headline figures, and it moves with specification. Structural glazing, a complicated roof and a high-end kitchen push it up quickly. A simple flat-roofed box with standard windows sits below it.
So it's a guide, not a quote. The rate moves with what you're building, the fee moves with the site and the brief. But it gives you the shape of the thing, which is usually what's missing at the start.
frequently asked questions _
how much does an architect cost for a house extension?
On a domestic project our fee is typically a percentage of the construction cost, between 5.5% and 7%, and the percentage comes down as the project gets bigger. It's charged on the cost of building the work, not the value of the house, and it excludes VAT, statutory fees and other consultants. Every figure stays indicative until we've seen the site.
what is the architect's percentage a percentage of?
The construction cost. That means the money that goes to the builder to build the work. Not what your house is worth. It also excludes VAT, planning and building regulations application fees, and the fees of other consultants such as a structural engineer.
which riba work stage costs the most?
Stage 4, technical design, is the largest single share, around 39% in our fee structure. It's where the drawings that actually get built are made, coordinated with the structural engineer and submitted for building control. Stages 1–2 are around 30%, stage 3 around 20%, and stages 5–6 around 11%.
is a fixed fee cheaper than a percentage fee?
Not automatically. Neither is cheaper by nature. A project with a clear, settled scope suits a fixed fee, because both sides can see what's being priced. A project still finding its shape suits a percentage, because the fee moves with the project instead of being renegotiated every time the brief develops. We do both, and decide case by case.
Where the honest answer is "it depends", we'd rather say so and then tell you what it depends on. For a figure against your own project, the architect fee calculator takes a couple of minutes and is honest about being indicative. When you want to talk about the project itself, start a project and we'll come and stand on the site with you. That's where the real number comes from.
we are _ is an architecture studio in Morley, Leeds, led by a registered architect and run by its two directors, Andrew Clapham and Jack Davey. We work across West Yorkshire, North Yorkshire and Lincolnshire.