Appraising a site before you pay for any planning reports
Most sites that fail do so because of something visible on a free public map. Here is the order to check them in, and the findings that should stop a purchase outright.
Half a day of free desk research will tell you more about whether a site is worth pursuing than the first £3,000 of consultant fees. Most sites that fail do so because of something visible on a public map: a functional floodplain, no lawful access, a Tree Preservation Order across the only buildable corner, a Green Belt boundary that runs through the garden. A site appraisal before planning spend exists to find those things while the only thing at risk is your afternoon.
The order matters. Check the constraints that can end the project first, then the ones that change the cost, then the ones that only change the design. Do not commission anything until the first group is clear.
Free public data worth checking first
Four sources cover most of what a desk appraisal needs, and none of them charges:
- The government planning data platform, which carries national datasets for conservation areas, listed buildings, scheduled monuments, Article 4 directions, Green Belt, National Landscapes, National Parks, sites of special scientific interest, flood risk zones and, for many authorities, Tree Preservation Orders and local plan boundaries.
- The Environment Agency's Flood Map for Planning, which gives the flood zone used in planning decisions, and the separate long-term flood risk service, which covers surface water and flooding from reservoirs.
- The MAGIC mapping service run by Defra, for ecological designations, priority habitat inventory, ancient woodland and provisional agricultural land classification.
- The council's own policies map and adopted plan, which show allocations, settlement boundaries and local designations that the national datasets do not hold.
Add the National Heritage List for England for listing details and the British Geological Survey viewer for geology and made ground. Water company asset plans are usually free on request and will show a public sewer crossing the plot, which is the sort of thing that quietly removes a third of a garden.
Record what you checked and when, with a screenshot of each result. That record becomes the first section of your scoping note and saves repeating the work in three months.
Flood zone, designations and protected trees
Flood zone is the fastest pass or fail. A site in Flood Zone 1 with no surface water hotspot needs very little flood work. Flood Zone 2 brings a site-specific flood risk assessment into the budget. Flood Zone 3a brings the sequential test, and Flood Zone 3b, the functional floodplain, rules out new homes in most circumstances. That single check can stop a purchase.
Heritage designations change the evidence base rather than preventing development. A listed building on or beside the site, a conservation area boundary, a registered park or a scheduled monument each pull in specialist work and lengthen the programme.
Trees need two checks. The council's TPO map or register, and the aerial photograph. A tree does not need an Order to constrain a layout, because a mature tree with a wide root protection area will shape the footprint either way, and any tree in a conservation area carries the same six-week notice requirement as a protected tree. Where trees are close to the developable area, assume a BS 5837 survey will be needed.
Ecology is harder to read from a desk. What you can establish is whether the site sits in a priority habitat, next to ancient woodland, which carries a standing buffer expectation, or inside a catchment where nutrient neutrality or recreational disturbance mitigation applies. Those catchment constraints can add cost and delay out of all proportion to the size of the scheme.
Adopted plan allocation and the settlement boundary
Look up the site in the adopted local plan before anything else that involves a judgement. Three answers are possible and each sets a different strategy.
Allocated for development: the principle is established and the work is about layout, access and the detailed policies.
Inside the settlement boundary but unallocated: a conventional development management case, judged against the plan's design, amenity and infrastructure policies.
Outside the settlement boundary: expect a policy objection in principle, and expect to need a specific policy hook such as infill, rural exception, conversion of an existing building or the reuse of previously developed land. Check also whether a neighbourhood plan covers the site, because a made neighbourhood plan forms part of the development plan and often carries its own boundary and site allocations.
While you are in the plan, note the plan's adoption date. An older plan with an out-of-date housing position changes the balance in a way that is worth understanding before you spend anything.
Access, ownership and third party land
More schemes die on access than on policy. Three questions settle it.
Does the site have a lawful vehicular access onto the public highway, and can that access achieve the visibility splays the highway authority expects for the road's speed? The adopted highway extent is on the highway authority's records, and the verge between a plot and the carriageway is often highway land rather than yours.
Is there land in another ownership between the site and the highway, or a shared private drive with rights that do not extend to new dwellings? A ransom strip discovered after exchange is expensive.
Does a public right of way cross the site, and does an easement for a sewer, a water main, a gas main or an overhead line restrict where you can build? Diverting a right of way or a service is possible, but it has its own procedure and its own timetable, and both run in parallel with planning rather than afterwards.
Utilities and the obvious deal breakers
Get indicative positions from the network operators before committing. Electricity capacity, a point of connection for water, foul drainage where there is no mains sewer, and the cost of diverting anything that crosses the site. These answers arrive in weeks and cost nothing to ask for, and they can move a budget by five figures, as they do whenever utility connections and diversions have to be priced into a scheme.
The list of findings that should stop a purchase outright is short: Flood Zone 3b, no achievable access, a designation that makes the proposed use unacceptable in principle, ground conditions that make the scheme uneconomic, or a restrictive covenant preventing development. Everything else is a cost, and costs can be priced.
What a half day of desk work can rule out
By the end of an afternoon you should be able to state, in writing, the flood zone, every designation touching the red line, whether the site is allocated, whether a neighbourhood plan applies, whether access is achievable, what crosses the site, and which protected trees constrain the layout.
That is enough to decide whether to walk away, to negotiate the price, or to move to the next stage. It is not enough to design anything, and it is not a substitute for a site visit. Walk the site and photograph the boundaries, because a desk appraisal will not show you the neighbour's window three metres from your boundary or the fact that the access is on a blind bend.
When to stop and when to spend
Spend money in this order, and only when the previous answer is positive. A topographical survey comes first on anything other than a flat plot, because every other consultant works from it. Then the appraisals that test the constraints you already know about. Then design. Then the reports that depend on a fixed layout.
Pre-application advice is usually worth buying once you have a sketch layout and a clear question, not before. Published fee bands vary between authorities, so check the council's current charges, and send a note that asks specific questions rather than inviting a general comment.
Turn the appraisal into a two-page scoping note: constraints found with their source and date, the reports each constraint triggers, the surveys with seasonal windows, and the decisions still outstanding. That note is what you give to a planning consultant or an architect, and it stops you paying twice for the same desk study. It also prevents the most expensive mistake in this field, which is a consent carrying a pre-commencement condition you cannot discharge.
A first draft of the supporting statements can be prepared once the layout settles; PlanScope pricing covers one free report, £50 per report, or Professional for unlimited reports if you are running several sites.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Which free sources should I check first on a new site?
Start with the planning data platform for designations, the Environment Agency Flood Map for Planning for the flood zone, the MAGIC service for ecology and agricultural land, and the council's own policies map for allocations and settlement boundaries. Add the National Heritage List for listing detail and the water company for asset plans.
What findings should stop me buying a site?
Flood Zone 3b functional floodplain for new homes, no achievable vehicular access or visibility, a designation that makes the proposed use unacceptable in principle, ground conditions that make the scheme uneconomic, and a restrictive covenant preventing development. Most other constraints are costs, and costs can be priced into the offer.
Do I need a topographical survey before anything else?
On anything other than a small flat plot, yes. Architects, drainage engineers, arboriculturists and transport consultants all work from the same levelled base, and commissioning them without one produces drawings that have to be redone. It is usually the first survey worth paying for.
When is pre-application advice worth buying?
Once you have a sketch layout and specific questions, not before. Authorities publish their own fee bands and these change, so check the current schedule. A note that asks targeted questions about policy compliance, access and the evidence expected will get a more useful answer than a request for general comments.
Can a desk appraisal replace a site visit?
No. Mapping will not show you a neighbour's window three metres from the boundary, an access on a blind bend, or the condition of a building. Walk the site, photograph every boundary and look at the relationship with surrounding properties before deciding whether the appraisal findings are workable.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.