Site Feasibility Study: What It Is, What It Costs, When to Commission It (2026 UK Guide)

A site feasibility study is the document that answers, for a specific site, what can be built, at what indicative cost, against what residual land value, and within what programme. It sits between the constraints check (is this site buildable at all) and the architect's design feasibility (how the scheme sits on the plot in 3D).

For most UK SME developers, a credible 2026 site feasibility study contains:

This guide is written for SME developers at pre-acquisition or option stage, architects briefing clients before RIBA Stage 1, and land buyers running multi-site investment committee papers.

Order a Site Appraisal → Site Appraisal for developers · See a sample report → see a sample Site Intelligence report

A site feasibility study is a distinct workstream from three adjacent documents people often confuse it with.

Constraints check / due diligence answers the prior question of whether the site is buildable at all. It identifies designations, fatal flaws and the abnormal cost triggers that would kill a scheme. That work is covered in the development land due diligence guide.

Architect's design feasibility answers how the scheme sits on the plot in 3D, including massing, daylight, overlooking and access. That is RIBA Stage 1 work, produced by an architect, not by a desktop site intelligence pack.

Full viability appraisal is formal RICS Red Book valuation work used in section 106 negotiation or financial reporting. A desktop pack does not provide that, and any provider claiming otherwise is misrepresenting scope.

A credible 2026 site feasibility study covers nine domains.

The PF & Co Feasibility Intelligence pack is the productised version of this scope and includes Developer, Architect and Technical Summaries plus a Client Decision Pack. The full breakdown is set out in what is included in our 48-hour desktop pack.

There are five buyer moments where commissioning a feasibility study typically saves more than it costs.

1. Pre-acquisition diligence. Before exchange, option signature, conditional contract or auction deadline, with the feasibility output going into the IC paper or the funder pack. SME developers running deposits, exclusivity fees and abortive professional fees against an option deadline use feasibility to test whether the asking price is supportable before non-refundable cash leaves the business. For a vendor asking price, the feasibility output is the evidence base for setting a maximum bid.

2. Pre-architect appointment. Before instructing concept design fees, the feasibility confirms there is a buildable scheme worth designing, and protects the architect's appointment scope and client brief from rework. Designing into a constraint stack the brief never tested is rework neither side gets paid for properly. RIBA Stage 0 (Strategic Definition) and Stage 1 (Preparation and Briefing) both call for feasibility-grade site information before concept design begins.

3. Multi-site portfolio review. Running ten sites through feasibility takes weeks at desktop pack speed and months at coordinated consultancy speed. Relative ranking is what matters for portfolio decisions, and ranking is only credible when every site has been assessed against the same methodology in the same window.

4. Lender or investor diligence. When a development loan or equity partner asks for evidence the scheme works, the feasibility output is the document that supports DSCR, LTC and LTV testing, the equity memo and the credit committee paper. A constraints check alone does not.

5. Pre-application preparation. Feasibility informs the pre-app submission and the case the LPA case officer responds to. Feasibility commissioned after pre-app is the most expensive iteration order. Feasibility commissioned before pre-app is the cheapest.

The pattern across all five moments is the same. Feasibility evidence is typically cheaper than the decision it informs, and the cost of skipping it is paid in unrecoverable fees, mispriced bids or planning routes that were never going to work. There are exceptions: some sites (heavily contaminated former industrial land, sites with active mining legacy, complex listed building curtilages) need early specialist input before a feasibility is meaningful, and the feasibility report should name those triggers up front.

The authoritative national datasets used at the desktop layer overlap heavily. The methodology difference is in integration, timing, liability and depth.

A desktop pack uses authoritative national datasets including Land Registry, Environment Agency, Defra MAGIC, Historic England, Coal Authority, BGS, Ordnance Survey, BCIS, the LPA's policies map, and comparable GDV evidence. A coordinated consultancy team typically draws on the same national datasets and may add paid local datasets, site visits, measured surveys, specialist judgement and proprietary evidence not available to a desktop provider.

Price and turnaround figures for consultancy feasibility are indicative ranges drawn from SME developer commissioning experience and vary materially by scope, region and lead consultant.

The desktop pack does not replace the chartered specialist work that follows where the scheme requires it.

Where the desktop feasibility flags risk, the report names the specialist study. Where the law or scheme complexity requires chartered specialist sign-off, those workstreams remain outside scope. The four-pack ladder, from Site Appraisal through Feasibility Intelligence, Pre-Application Pack and Planning Intelligence Pack, is built so each upgrade adds the next layer rather than duplicating the last.

Three named differences justify the upgrade from constraints check to feasibility study.

1. Scheme capacity. A constraints check tells you what designations apply to the site. A feasibility study tells you how many dwellings the developable area supports across density bands, after net-developable-area deductions for access, drainage, open space and constraint setbacks.

2. Indicative residual land value. A constraints check identifies abnormal cost triggers. A feasibility study estimates indicative cost ranges and tests whether the residual land value supports the price the vendor is asking. Buying a site at an asking price the residual land value cannot justify is a failure mode a feasibility catches and a constraints check does not.

3. Decision-grade IC paper output. A constraints check is a screen. A feasibility study is the document that goes to investment committee, board or funder. Different audience, different evidentiary bar.

An illustrative worked example. The figures below are illustrative only, based on a hypothetical 0.4-hectare urban-edge site with stated assumptions. Actual figures vary materially by location, market evidence, policy and constraint stack.

Assumptions: 0.4 ha site, urban-edge, Coal Authority CMRA trigger, Article 4 area, conservation area boundary 30 metres off the site, no fatal flaw identified at constraints stage.

The constraints screen output: amber, proceed with feasibility.

The feasibility study output, structured as a residual calculation:

Different document, different decision. The constraints screen tells you whether to keep going. The feasibility tells you what to bid.

For a closer look at how the constraints layer feeds into feasibility, see the site appraisal report (2026 UK guide).

1. Commissioning architect concept design before feasibility. Concept design fees against a scheme the policy or constraint stack does not support are unrecoverable cost. The architect cannot refund time spent designing into a brief that was never feasibility-tested. The fix is to commission feasibility first and hand the architect a constraint-led brief, not a blank sheet, which protects the architect's design-fee scope and the client brief.

2. Using a constraints check as a feasibility. The constraints check tells you whether the site is buildable. It does not tell you what the scheme is worth. Using a constraints output for a bid or a board paper is the planning equivalent of pricing a building from a structural engineer's reservation hold rather than a cost plan. Both documents are useful. They answer different questions.

3. Commissioning a feasibility after pre-application advice. Pre-app advice is most useful when the LPA case officer responds to a feasibility-tested scheme with worked indicative numbers and a clear access, drainage and density rationale. Without that, pre-app is a generalised conversation, and the response is generalised. The case officer cannot give scheme-specific advice on a scheme that has not been specified.

In most cases, the right order is feasibility before specialist commission, feasibility before architect concept design, feasibility before pre-app. The PF & Co four-pack ladder is structured to support that order: Site Appraisal as the constraints entry, Feasibility Intelligence as the feasibility upgrade, Pre-Application Pack once the feasibility supports a planning route, and Planning Intelligence Pack tailored once the architect has engaged.

For the wider report-cost benchmark across the sector, see the planning report cost benchmark for 2026.

Architects working at RIBA Stage 0 (Strategic Definition) and Stage 1 (Preparation and Briefing) need feasibility-grade evidence on planning, constraints and indicative cost before scheme design begins. Stage 0 establishes the business case, project risks and site appraisal. Stage 1 brings together the project brief, feasibility studies and site information to inform concept design.

The desktop site feasibility study is one input to the architect's design brief. The evidence required varies by project scale, procurement route and client. For pre-acquisition and small-developer briefs, a desktop pack covers the planning, policy and indicative cost evidence at a level that gives the architect a constraint-led starting point rather than a blank sheet. Larger or more complex projects may need additional inputs before Stage 1 begins.

This is not a substitute for the architect's own feasibility work. The desktop pack and the architect's design feasibility are two distinct workstreams that follow each other in the right order. The desktop pack establishes what the policy and constraint envelope allows. The architect's design feasibility establishes how the scheme sits within that envelope in 3D. Done in that order, the architect's fee buys design work, not constraint discovery, which protects appointment scope and reduces client brief liability.

For architects supporting clients on early-stage acquisition, the feasibility output also functions as the evidence pack the client needs for their IC, lender or option-fee decision. That part of the workflow is supported through the same pack referenced from Site Appraisal for developers.

The buying flow is straightforward.

Required inputs checklist. Postcode and full address, red-line boundary as a georeferenced file (GeoJSON, KML, shapefile or a clearly marked PDF / image with a scale and north arrow), intended use class, indicative dwelling count or floor area, vendor asking price or option strike if known, and any constraint information already obtained (search results, prior reports, agent particulars).

The deliverable covers the planning policy read, scheme options at density bands, indicative GDV, indicative build cost, indicative residual land value, the constraint-triggered specialist schedule, the risk register, and a decision-grade summary written for the IC or funder audience. The pack also includes the Developer, Architect, Technical and Risk summaries, plus the Client Decision Pack in plain English.

For wider context on how feasibility fits into the full planning evidence stack, see what reports you need for planning permission and the development land due diligence main page.

For most SME developers, land buyers and architect-led teams running pre-acquisition or pre-architect feasibility, the order is the same: confirm the constraint position first, then upgrade to the feasibility pack.

Step 1. Order a Site Appraisal from £199. The constraints entry point. Confirms whether the site is buildable, identifies designations, fatal flaws and abnormal cost triggers, and feeds directly into the feasibility upgrade.

Step 2. Upgrade to Feasibility Intelligence from £895. The full feasibility report covering policy, scheme options, indicative GDV, build cost and RLV, abnormal cost provisions, specialist schedule, risk register, and Developer, Architect, Technical and Risk summaries plus the Client Decision Pack. Delivered 48 hours from confirmed brief.

Step 3 onward. Pre-Application Pack once the feasibility supports a planning route, then Planning Intelligence Pack tailored once the architect has engaged.

Order a Site Appraisal → Site Appraisal for developers · See a sample report → see a sample Site Intelligence report

What this desktop report does not replace. The desktop feasibility study informs decision-making at pre-acquisition, pre-architect and pre-application stages. It is not a chartered RICS Red Book valuation, an MRTPI formal planning representation, a CMLI Landscape and Visual Impact Assessment, a chartered transport assessment with junction modelling, a chartered drainage engineer signed-off strategy, or an architect's design feasibility. Where the scheme requires any of those, the feasibility report names the specialist study, the indicative cost range and the typical timeline. Indicative GDV, build cost, abnormal cost and residual land value figures are ranges based on comparable evidence and BCIS data; they are not formal viability appraisal outputs and they are not warranties.