Worked example. The instructive part is that two routes open at once, and they open for different reasons. Filling a gap between houses stands on its own facts. Unmet need is a separate door, and because this site is outside the Green Belt an unmet self-build register duty counts towards it. Move the same site into the Green Belt and that second door shuts, because the wording there is narrower.

Policy sandbox

7 of 10 answeredShow policy detail

Change anything and the assessment on the right updates immediately. Nothing is saved, and the address bar holds your scenario so you can send it to someone.

Start from an example

Edge-of-village paddock Redundant farm yard Field near a well-served station

Where does the site sit?

Green Belt takes precedence over everything else. The glossary excludes villages lying within and defined as part of the Green Belt from the meaning of settlement, so such a village is not a settlement for S4 purposes. A settlement also includes land already allocated or permitted that will form part of the built-up area once complete.

Wholly within a settlementPredominantly built-up area, including land allocated or permitted that will form part of it.Outside any settlementStraddles a settlement boundaryWithin the Green BeltVillage lying within the Green BeltExcluded from the meaning of settlement, so the S4 default yes is unavailable however built-up the frontage appears.Local Green Space

Land and buildings

Each tick opens a different limb. Claim every one the facts support: they are alternatives, not a hierarchy.

Previously developed landLawfully developed land with a permanent structure or substantial fixed hardstanding. Excludes gardens, parks, allotments and land last used by agricultural or forestry buildings.An existing lawful building of permanent and substantial constructionAllocated for housing in the development planReads as infilling within a group of housesNeither limited nor group of houses is defined, and both are read tightly at appeal.Isolated: outside any settlement or group of housesS5(3) removes isolated homes from the S5 list altogether, leaving HO11 as the only route. A significant answer: tick it only if the site is genuinely on its own.Residential garden, park or allotmentLast used by agricultural or forestry buildingsA redundant or disused building to be reusedWould substantially harm an allocation or safeguarding for another useS4(2)(a)(i). Distinct from being allocated for housing, which is a positive at S5(1)(i). Does not apply where there is no reasonable prospect of the allocated use coming forward.

What kind of housing is proposed?

Open market housingSelf-build or custom build plotsA single self-build dwellingAffordable-led, or a rural exception siteCommunity-led developmentOlder persons or specialist accommodationMixed use including residentialUnder a Community Right to Build Order or Neighbourhood Development Order

Scale of development

Major for housing is 10 or more homes, or a site of 0.5 hectares or more. Either limb is sufficient. Strategic is a defined term: phased, masterplanned, significant infrastructure.

Minor: under 10 homes and under 0.5 hectaresMajor: 10 or more homes, or 0.5 hectares or moreStrategic: phased, masterplanned, with significant infrastructure

Evidenced unmet need

S5(1)(j) is open wording: any evidenced unmet need can qualify. GB7(1)(g)(ii), through footnote 41, is closed: for housing it means only a five year supply shortfall including any buffer, or a Housing Delivery Test result below 75%. The same phrase, two different reaches.

No five year supply of deliverable housing sitesHousing Delivery Test result below 75%Evidenced unmet affordable housing needOther evidenced unmet need: older persons, specialist, rural or self-buildNeed is met on every measure

Relationship to the settlement

Physically well-related has no test and no distance attached to it. It is the main battleground for edge-of-settlement sites. Footnote 28 covers only land beyond an undeveloped allocation.

Physically well-related to the settlement or the stationOf a scale existing or proposed infrastructure can accommodateExisting or proposed lets you rely on infrastructure that does not yet exist. How firm the proposal must be is untested.Adjoins the settlement edgeSits beyond the far edge of an undeveloped allocationFootnote 28: consider whether the location would still be suitable if the allocated development does not proceed.

Is the site within reasonable walking distance of a station?

Reasonable walking distance is around 800 metres, or around 10 minutes' walk time where topography, route availability and quality, or physical barriers would prevent or discourage walking from up to 800 metres. Where only part of the site is within that distance, the station limbs and the density floor apply only to that part.

No station within reasonable walking distanceYes, the whole site is within 800 metresYes, but only part of the siteWithin a 10 minute walk, with barriers applying

Self-build and custom build

The Framework has no self-build decision-making policy. Weight is assembled from HO1(2)(i) and HO7, and, outside the Green Belt only, the open unmet need limb at S5(1)(j).

Plots would count against the authority's self-build registerThe authority is behind its permissions duty under the 2015 ActA statutory duty, not a Framework policy. Outside the Green Belt this is an evidenced unmet need on the open wording of S5(1)(j). Inside it, footnote 41 shuts it out.Self-build need is assessed in the plan evidence under HO1(2)(i)The plan identifies no self-build plotsServiced plots, sold to individualsWilling to accept a self-build occupancy condition or a s106

Design quality

DP3 attaches weight to design quality generally, and is not confined to isolated sites. Separate from the HO11(1)(e) route.

Outstanding or innovative design, or high sustainability standardsWould improve the energy efficiency of an existing building, or draw on district heat, renewable or low carbon sources

Scheme quantum

Fills the major threshold and the density calculation. Net developable area excludes spine roads, attenuation and open space.

HomesSite area (ha)Net developable (ha)

Into the enhanced balance. 2 routes in play, 1 awaiting answers.

Falling within any S5(1) limb means approval unless the benefits are substantially outweighed. Claim every limb the facts support: they are alternatives, not a hierarchy.

012 questions still to answer

Within reasonable walking distance of a well-connected station, being around 800 metres or a 10 minute walk where barriers applyLivedinS5(1)(h)
Well-connected: within a top 80 Travel to Work Area by Gross Value Added, and served throughout the weekday daytime by at least 4 services per hour overall or 2 in any one directionLivedinS5(1)(h)

03Principle of development

Every limb tested in parallel. They are alternatives, not a hierarchy.

S5(1)(j)

Development addressing an evidenced unmet need

Open

An evidenced unmet need. The wording is "including, but not limited to" a five year supply failure or a Housing Delivery Test result below 75%, so it is not confined to those twoS5(1)(j)Met
An unmet self-build register duty is an evidenced unmet need on this open wording, which is the crucial difference from GB7(1)(g)(ii)S5(1)(j)Met
Physically well-related to an existing settlement, unless the nature of the development makes that inappropriateS5(1)(j)(i)Met
Of a scale which can be accommodated taking into account the existing or proposed availability of infrastructureS5(1)(j)(i)Met

S5(1)(e)

Limited infilling within groups of houses

Arguable

Reads as infilling within an existing group of housesS5(1)(e)Met
Limited on the facts. Neither limited nor group of houses is defined, and both are read tightly at appealS5(1)(e)Judgement
Self-build plots on an infill frontage are a well-trodden version of this limbMet

S5(1)(h)

Residential or mixed-use development around a well-connected station

Unresolved

Within reasonable walking distance of a well-connected station, being around 800 metres or a 10 minute walk where barriers applyS5(1)(h)(i)Not answered
Well-connected: within a top 80 Travel to Work Area by Gross Value Added, and served throughout the weekday daytime by at least 4 services per hour overall or 2 in any one directionAnnex BNot answered
Residential or mixed-use developmentMet
Physically well-related to the station, or to the settlement within which the station is locatedMet
Of a scale which can be accommodated taking into account the existing or proposed availability of infrastructureMet
Would not prejudice any proposals for long-term comprehensive development in the same locationMet
The L3 density floor runs alongside this limb. It is not one of its requirements, but a failure mandates refusal under L3(4)L3(2)(c)N/A

S5(1)(c)

Reuse, extension, alteration or replacement of an existing building

Not made out

An existing building of permanent and substantial construction, lawful in planning termsS5(1)(c)Fails
No disproportionate increase in size compared to the building as it stood on 17 August 2026S5(1)(c)Fails
If a replacement: for the same use, and not disproportionately larger than the building it replacesS5(1)(c)Fails

S5(1)(d)

Redevelopment of previously developed land

Not made out

Meets the definition of previously developed land: lawfully developed, with a permanent structure or substantial fixed hardstandingS5(1)(d)Fails
Not excluded as a residential garden, park or allotment, nor as land last used by agricultural or forestry buildingsAnnex BFails
The remains of any permanent structure have not blended into the landscapeAnnex BFails

S5(1)(f)

An exception site under HO10, or development under a Community Right to Build Order or Neighbourhood Development Order

Not made out

An exception site as provided for in HO10, or development brought forward under a Community Right to Build Order or Neighbourhood Development OrderS5(1)(f)Fails
Adjoins or is physically well-related to a settlementHO10Met
Includes affordable housing, with market homes only where essential to deliver it without grantHO10Fails

S5(1)(g)

Evidenced unmet need for gypsy, traveller or travelling showpeople accommodation

Not made out

Not assessed by this tool. This limb turns on HO12, on a five year supply of deliverable traveller sites rather than of housing sites, and on a locational test that treats sites not well-related to settlements as potentially appropriate. Take advice.

S5(1)(i)

Development of land allocated for that purpose in the development plan

Not made out

Allocated for housing in the development planS5(1)(i)Fails

04Constraint screen

None engaged. Re-run once technical work is in: density and transport catch schemes late.

05Weight ledger

Only weights the Framework directs, at the strength the answers support.

Consideration	Policy	Weight
Homes contributing to evidenced accommodation needsHO7(1) directs substantial weight to the benefits of providing homes contributing towards evidenced accommodation needs, as identified through the authority's needs assessments and other relevant evidence.	HO7(1)	Substantial
Self-build as an assessed need groupcheckThis reaches HO7 only where the plan evidence assesses self-build need. Where it does not, that gap is itself the argument rather than the weight.	HO1(2)(i)	Not established
Authority behind its permissions dutyA statutory duty rather than a Framework policy, so the Framework directs no particular weight to it and the quantum is for the decision-maker. Outside the Green Belt it also supports the open unmet need limb at S5(1)(j).	Self-build and Custom Housebuilding Act 2015	Undirected
Any development plan policy materially inconsistent with this FrameworkcheckA prompt rather than a finding. Identify the specific policies and the specific inconsistency: the tool cannot read your development plan. Most restrictive rural housing policies now sit here.	Introduction / Annex A	Very limited

06Interpretation register

Undefined language this case would turn on.

“substantially outweighed”S4, S5, GB7: Undefined, and the whole balance turns on it. Materially higher than the old significantly and demonstrably formulation, with nothing in the Framework saying how much higher.
“settlement”Annex B: Points at development plan definitions, but where boundaries are undefined the extent is argued from predominantly built-up area. Includes land allocated or permitted that will form part of the built-up area once complete. Villages within and defined as part of the Green Belt are carved out entirely.
“evidenced unmet need”S5(1)(j) against GB7(1)(g)(ii): The most important asymmetry in the document for small and self-build sites. S5(1)(j) says including, but not limited to, a five year supply failure, which is open. Footnote 41 to GB7(1)(g)(ii) says that for housing it means a five year supply shortfall including any buffer, or a Housing Delivery Test result below 75%, which is closed. The same phrase, two different reaches.
“people wishing to commission or build their own homes”HO1(2)(i): The route by which self-build demand becomes an assessed need and so reaches the substantial weight at HO7. Where the plan evidence does not assess it, that gap is itself the argument.
“physically well-related”S5(1)(h)(ii), S5(1)(j)(i), GB7(1)(h)(ii): No test, no distance. Footnote 28 covers only land beyond an undeveloped allocation. The main battleground for edge-of-settlement sites.
“a scale which can be accommodated”S5(1)(h)(iii), S5(1)(j)(i), GB7(1)(h)(iii): Existing or proposed lets you rely on infrastructure that does not yet exist. How firm the proposal must be is untested.
“limited infilling”S5(1)(e), GB7(1)(c): Neither limited nor group of houses is defined, and both are read tightly at appeal. The pinch point for multi-plot self-build frontages.
“very limited weight”Introduction / Annex A: What a materially inconsistent development plan policy now gets. Not zero, and the quantum is for the decision-maker case by case, which is where most restrictive rural housing policies now sit.

Assessed against the National Planning Policy Framework (2026), published 17 August 2026, using ruleset 1.0.0 and interpretation revision 2026-08-18.

This is a sandbox, not an assessment

Everything above comes from the answers on the left. It has not looked at a map, a local plan, or the planning history of any particular site. If you have a real piece of land, the assessment starts from its boundary instead, and fills in what it can from the data.

Assess an actual site