An architectural feasibility study in the UK typically costs between 0.75% and 1.5% of the total project cost. For a smaller scheme, that can mean £2,000 to £4,000 in practice, while larger developments can run into tens of thousands of pounds as the level of risk, detail, and consultant input rises.
That is the right way to think about it if you've got a site, a house, or a development idea and you're asking one question first, can this really work? A feasibility study is the early spend that helps you avoid committing far more money to the wrong site, the wrong layout, or the wrong planning approach.
Your Project's First Step The Feasibility Study
You might be looking at a vacant plot, an attic conversion, or a mixed-use site and trying to work out whether it's worth pushing ahead. That's exactly when an architectural feasibility study earns its keep, because it tests the idea before you commit to full design fees, surveys, and planning submissions.
In the UK, the RIBA Plan of Work places feasibility right at the start, in Stage 0 Strategic Definition and Stage 1 Preparation and Brief. That formalises the study as a pre-design gate for testing viability before bigger design and planning costs arrive, rather than treating it as an optional desktop exercise (RIBA Plan of Work context).
Practical rule: if the site, brief, or planning position feels uncertain, spend early to buy clarity. That's far cheaper than discovering a fatal constraint after the design team has already gone deep.
For a client, the point isn't to pay for drawings. The point is to buy a clear answer on constraints, options, and likely route to delivery. If you're reviewing a project pipeline, the work shown on FP Architects' project portfolio is a useful reminder that feasibility sits behind every serious scheme, even when the final building looks effortless.
What a Feasibility Study Actually Includes
A proper feasibility study is more than a sketch and a quick opinion. It should give you enough information to decide whether to proceed, pause, or change direction before the project starts consuming real time and money.
The core pieces you should expect
A robust study usually covers:
- Site and context analysis. This looks at the plot, access, surrounding buildings, orientation, and obvious physical constraints.
- Planning and policy review. The architect checks whether the local planning position supports the idea, or whether there are red flags that need attention.
- Early massing or layout options. You should see at least one realistic way the building could sit on the site, even if it's only at outline level.
- Constraints mapping. Existing structures, neighbouring rights, access issues, and other pinch points need to be identified early.
- High-level delivery thinking. A good study doesn't stop at form. It links the idea to a practical path to construction, approvals, and next-stage design.
What doesn't help is a vague mood board with no decision value. If the output can't inform a yes or no, it's too thin to be called feasibility work.
A useful way to judge quality is to ask whether the study gives you options, not just a preferred answer. A single concept can be useful, but in most residential and mixed-use cases, decision-making improves when the architect shows where the idea can flex, where it can't, and what would make it more viable.
If the output doesn't help you compare alternatives, it's probably not a feasibility study. It's an early concept sketch wearing a more serious label.
The best studies also capture uncertainty transparently. They should tell you what is known, what still needs survey input, and what assumptions are being made. That transparency matters because hidden assumptions are what later blow up budgets and programme expectations.
Typical Feasibility Study Costs in the UK
A feasibility study is often the first real spend on a project, and its cost should be read against the risk it removes. Industry guidance commonly places feasibility study fees at 0.75% to 1.5% of the total project budget, and some sources say feasibility work is rarely more than 1% of the budget (feasibility study cost guidance).
For a £500,000 project, that usually puts the feasibility allowance at roughly £3,750 to £7,500 before specialist surveys are added. That is a sensible range for a refurbishment or small new-build, where the study needs to be detailed enough to surface planning risk, structural issues, and access constraints before the design team commits to a direction.
Percentage fee or fixed fee
Both pricing models have a place. A percentage fee suits a brief that is still open, a site with unknown constraints, or a project where the amount of testing may grow once the first round of checks is done. A fixed fee works better when the scope is clearly defined and the deliverables can be agreed from the outset.
For smaller projects, many clients prefer a set fee because it gives a clean decision point. For more complex projects, a percentage-based approach can be fairer because the amount of work needed to reach a reliable answer is harder to predict on day one.
| Project Type | Typical Construction Budget | Estimated Feasibility Study Cost |
|---|---|---|
| London house extension | Lower to mid six figures | Often around the £2,000 to £4,000 level, depending on detail and options |
| Detached new-build home | Mid six figures to low seven figures | Usually sits above the basic extension level because of greater site and planning testing |
| Small residential development, 3 to 5 units | Higher six figures to multi-million pounds | Commonly moves into a broader early-stage budget because more consultant coordination is needed |
A London scheme is a useful benchmark. For a typical housing scheme in London, feasibility can cost £2,000 to £4,000, with the final price shaped by the level of detail, site complexity, and the number of design options required (London feasibility benchmark).
For a completed project, the early outlay is usually modest against the cost of choosing the wrong route. A careful study can stop a scheme from drifting into an option that looks efficient on paper but fails once planning, structure, or buildability are properly tested.
Key Factors That Drive Your Feasibility Costs
Cost rarely comes down to page count. It comes down to how much thinking, testing, and consultant coordination the site demands before anyone can make a confident decision.
Risk multiplies the work
A key driver is regulatory risk. Two projects with the same floor area can end up with very different feasibility costs if one needs a flood risk assessment, a heritage impact statement, or transport consultant input, which turns a simple study into a multi-consultant exercise (regulatory risk and feasibility).
That's the part many generic cost guides miss. The architect's time matters, but the bigger cost jump often comes from everything the architect has to coordinate around the brief. If a site sits in a sensitive planning area, the study has to work harder before a single line of technical design can be trusted.
Site complexity changes the amount of testing
A flat, straightforward plot is one thing. A constrained urban site, awkward access, tight neighbours, or an existing building with uncertain condition is another. Each of those factors can push the study from a quick review into repeated option testing.
The same applies to the brief itself. A single-use home extension is usually simpler than a mixed-use or development scheme because there are fewer competing requirements to balance. Once you start testing multiple layouts, servicing routes, access arrangements, and planning responses, the study grows in scope.
More options mean more time
The number of design options is a direct cost driver. One well-considered option may be enough for a go or no-go decision, but if the client wants a choice between several massing directions, the architect has to assess each one for fit, planning logic, and practicality.
The cheapest study is not always the best value. If it leaves the big risks unresolved, you may pay for the same thinking again later.
London projects often feel this most sharply because planning conditions, neighbouring constraints, and local sensitivity can all shift the amount of early work needed. A good feasibility study is priced around the actual risk profile of the site, not just the drawing time.
Sample Budgets for Common UK Project Types
A useful way to judge value is to compare like with like. A small extension, a new home, and a small development all need feasibility work, but they do not need the same depth of testing.
| Project Type | Typical Construction Budget | Estimated Feasibility Study Cost |
|---|---|---|
| Single-house extension in London | Lower six figures to mid six figures | About £2,000 to £4,000 for many straightforward schemes |
| New-build detached home in the home counties | Mid six figures to low seven figures | Often above the simple extension level because the site, servicing, and planning response need more testing |
| Small residential development, 3 to 5 units | Higher six figures to multi-million pounds | Usually requires broader early-stage input because the brief, access, and planning implications are more complex |
For a homeowner, the extension case is usually about whether the scheme is buildable, whether it fits the existing house, and whether it is likely to receive a sensible planning response. For a developer, the same fee has to do more work. It needs to support acquisition, risk appraisal, and exit planning before the project is committed to.
London and the wider UK market add another layer. A quote for a feasibility study can rise quickly once heritage rules, conservation area controls, flood risk checks, overlooking concerns, or difficult local planning policy start to shape the design response. Those pressures often cost more than the architect's drawing time, because they may require extra testing, planning strategy, and input from other specialists.
A better way to think about it is this. The feasibility fee should scale with how much uncertainty the study has to remove before you can make the next financial decision. A small project with awkward constraints can cost more than a larger but cleaner one, especially where the site sits in a sensitive part of London or needs careful planning justification.
If you are working from a wider acquisition and delivery model, the property investment blueprint gives a practical frame for separating design cost from return, timing, and risk allocation. The same logic applies whether you are assessing a house, a block of flats, or a mixed-use site.
A real example is an attic conversion with planning sensitivity, where the layout may be simple but the planning response and neighbour impact still need proper checking. A scheme like this attic conversion project in Wisteria Road shows why a modest project can still need careful early-stage work. The cost is rarely just about drawings. It is about reducing the risk of taking the wrong next step.
The most important point is that feasibility is still a small line item compared with the total build. If the study stops you from buying the wrong site, overdesigning the brief, or pursuing an impossible planning route, it has already done its job.
How to Scope and Procure a Study to Control Costs
The easiest way to overspend is to ask for too little detail at the start and then keep adding extras mid-stream. A clear brief gives the architect a better chance of pricing accurately and gives you a better chance of getting something decision-ready.
Start with the questions you need answered
Before you ask for a fee, write down the decision you need to make. Are you testing whether the site is worth buying, whether the planning route looks realistic, or whether the current building can be reworked within a sensible budget?
Then ask the architect to state clearly what's included and what isn't. Survey fees, planning pre-application fees, specialist consultant costs, and third-party reports should be separated where possible so you can see which parts are part of the architect's effort and which parts are project-wide costs.
A key question for UK developers and homeowners is not just the total cost, but how that cost is allocated and whether some elements, like detailed surveys, would be needed later anyway (allocation of feasibility costs). That distinction matters because some items are true sunk costs, while others are early spend you'd likely need in any case.
Treat the brief as a cost-control tool
A tight brief doesn't mean a smaller ambition. It means a clearer one. If the team understands the site constraints, your delivery target, and the level of risk you're prepared to carry, the fee proposal will usually be easier to interpret.
The most useful fee conversations are simple:
- Ask what the study will prove. If the answer is vague, the output probably will be too.
- Ask how many options are included. More testing means more time, so make the choice deliberate.
- Ask what happens if a major constraint appears. That tells you whether the study can adapt without derailing the budget.
- Ask which parts are recoverable later. Some early spend is duplicated if the project progresses, some isn't.
If you want a wider view of how practitioners talk about early-stage project setup, the FP Architects blog is a practical place to compare how feasibility thinking shows up across different project types.
Frequently Asked Questions
Is the feasibility fee deducted from later architectural fees?
Sometimes, but not always. It depends on the appointment structure and the practice's terms. Some firms credit part of the early work if the project proceeds, while others keep feasibility separate because it is a distinct piece of advisory work.
How long does a feasibility study take?
It depends on the site, the amount of testing needed, and how quickly information comes back from the client and consultants. A simple residential review can move quickly, while a more complex London site with planning sensitivity, heritage issues, or flood risk takes longer because more inputs have to be checked.
What if the study says the project shouldn't proceed?
That's still useful work. A good study can save you from a weak purchase, an unrealistic brief, or a planning strategy that would have become expensive later. If the answer is no, you still walk away with a clearer basis for the next decision.
If you're weighing up a site, an extension, or a mixed-use opportunity, speak to FP Architects early and ask for a feasibility scope that separates risk, surveys, and design effort clearly. That conversation is the fastest way to turn a vague idea into a sensible, costed next step.