What does a feasibility study include? What it tells you, and what it doesn't

What is a feasibility study in architecture?

The RIBA Plan of Work 2020 puts feasibility studies at Stage 1, Preparation and Briefing. Its overview says Stage 1 "is about developing the detail of the brief", including "ensuring that the brief can be accommodated on the site". It describes feasibility studies like this:

"Feasibility studies are carried out as part of the briefing process to verify whether a site can accommodate the client's needs, or to test a particular aspect of the brief, allowing the brief to be honed as required."

Two points follow from that, and both are useful when you're commissioning one.

It's a test of the brief, not the start of the design. The RIBA is clear that the design of the building starts at Stage 2. A feasibility study can show several ways a site could work; it doesn't pick a final scheme or draw it in detail.

Its job is to change your mind if it needs to. A good study ends with a decision: go ahead, change the brief, or walk away. If you'd go ahead whatever it says, it isn't worth commissioning.

For a developer looking at a site, the brief is usually some version of "how many homes, of what kind, and how risky is it?" We cover the capacity side of that in How many homes can I build on my land?.

What does a feasibility study include?

Scope varies from practice to practice, so ask for it in writing. A site feasibility study for residential development usually covers six things.

1. The site and its constraints. A site visit and a map of what shapes the site: access, trees, levels, neighbours and their windows, flood risk, heritage designations, easements and services. This sets the land you can actually build on.

2. Planning policy and history. The local plan, any design code or conservation area appraisal, national policy, and the planning history of the site and its neighbours. Past refusals, appeals and approvals nearby often tell you more than policy wording does.

3. Capacity options as massing. Not one answer, but a few: for example, a lower, wider option and a taller, narrower one. Each is a 3D envelope you can see in its context, so you can compare height, bulk and impact on neighbours.

4. Unit mix and areas. For each option, how many homes fit, of what size, and how much floor area goes to stairs, corridors and stores. In England, we check homes against the nationally described space standard (NDSS), which applies where the local plan adopts it.

5. Planning risk, issue by issue. A view of where each option is likely to meet resistance, and why: height, density, design, heritage, neighbours, affordable housing, parking or something specific to the site. The RIBA says feasible options shouldn't be narrowed down at Stage 1, so a rating of each option's risk is more useful than a single recommendation.

6. What to check or commission next. The surveys, specialist reports and advice the options depend on, and in what order. This is often the most practical page in the report.

What a feasibility study doesn't include

Most disappointment with feasibility studies comes from expecting them to answer questions they were never meant to answer. Here's what's outside the scope, and who covers it.

Planning permission. Only the local planning authority can grant it, through a planning application. A feasibility study is a professional view of the risk, not a prediction of the decision. Pre-application advice doesn't settle it either: Planning Practice Guidance says pre-application advice "cannot pre-empt the democratic decision making process or a particular outcome", although it could be a material consideration.

A valuation or viability assessment. A feasibility study by an architect isn't a RICS valuation, and it doesn't replace a formal viability assessment for planning. For those, you'll need a valuer or viability consultant.

Building Regulations approval. A feasibility study should flag the rules that shape the building at this early stage, such as fire safety and staircases, but approval comes later, from building control.

Surveys. Topographical surveys, ground investigations, tree surveys, ecology surveys, flood risk assessments and drainage studies are specialist work. A study tells you which ones you need.

Legal advice. Title, rights of way, restrictive covenants and rights of light are legal questions. A feasibility study can flag a likely rights of light issue; it can't tell you what it means legally. Ask your solicitor.

A daylight and sunlight report. Daylight considerations in a massing study are high level. A formal daylight and sunlight assessment is a separate specialist report.

Detailed design. Floor plans you could build from, elevations, materials and specifications come at RIBA Stages 2 and 3 and beyond. Feasibility massing shows what could fit, not what the building will look like.

None of this makes the study less useful. It's the cheapest point in a project to find out that a site doesn't work, and the study tells you which of those specialist questions you need to answer next.

Feasibility, pre-app and planning: the order of things

It helps to see where a feasibility study sits in the wider process. The RIBA Plan of Work 2020 sets out the planning steps it calls core statutory processes:

• Stage 1: "Source pre-application Planning Advice".
• Stage 2: "Obtain pre-application Planning Advice".
• Stage 3: "Prepare and submit Planning Application". The RIBA notes that planning applications "are generally submitted at the end of Stage 3".

What pre-application advice is

Pre-application advice is the council's informal view of a proposal before you apply. Most councils run a paid service with a written response, and often a meeting.

• It isn't always required, but it's expected for bigger schemes. Under the National Planning Policy Framework (August 2026), policy DM1, applicants for major development are expected to engage early, including through pre-application engagement. For housing, major development means 10 or more homes or a site of 0.5 hectares or more (NPPF glossary).
• Councils may charge for it. Planning Practice Guidance says councils can charge under section 93 of the Local Government Act 2003, and charges must not exceed the cost of providing the service. Check your council's fee schedule.
• It isn't binding, as above. But NPPF policy DM3 asks councils to take account of planning matters raised during any pre-application engagement when they decide applications.

Why feasibility comes first

Pre-application advice is far more useful when you go in with a tested idea. A feasibility study gives you the options, the constraints and the questions to ask: "Would you support five storeys here?" is a better pre-app question than "What can I build?". It also means you go to the council only with options the site can take.

How to read the results

When the report arrives, look for three things.

A range, with reasons. Capacity should come as a range across the options, each with its assumptions stated. A single number with no reasoning is a red flag.

The risks that would change the answer. Which issues could cut the number of homes, or stop the scheme? Which surveys or reports would settle them, and how quickly?

The decision it points to. Go ahead (perhaps to pre-application advice), change the brief (fewer homes, a different mix, a different height), or walk away. A study that leads you to walk away from the wrong site has done its job.

When to commission one, and what to bring

The best time is before you commit: before you exchange on a site, agree a price based on a number of homes, or appoint a full design team. A study can also help if you already own land and want to know whether to apply, or if a scheme has been refused and you want to test a different approach.

It helps to bring:

• the site address and a plan of the boundary;
• any sales particulars, title plan or survey you already have;
• the planning history you know about, including any pre-application advice;
• your brief: what you'd like to build, and anything you won't compromise on;
• your timescale and any deadlines, such as an exchange date.

What a Feasibility Sprint includes

Our Feasibility Sprint is a fixed-scope feasibility study for one site in England, with a fixed fee quoted per site after a free intro call. It includes:

• a site visit;
• a planning policy and history review;
• a constraints map;
• three massing options, tested computationally against the site's constraints;
• a unit mix and area schedule for each option, checked against the NDSS, with net-to-gross;
• a planning risk rating (red, amber or green) for each option, with our reasoning;
• a written PDF report (about 15–25 pages), the 3D massing model and a 1-hour review call.

The target delivery is 10 working days from the Start Date. It isn't a valuation, a viability assessment, a daylight report, a planning application or a design appointment.

Frequently asked questions

Testing a specific site?

If you're weighing up a site, the Feasibility Sprint tests it before you commit to it: three options, the planning risks, and what to check next. It covers sites in England.

Book a free intro call or see the Feasibility Sprint.