Affordable housing on custom and self-build schemes

Most self-build and custom housebuilding schemes never reach the affordable housing threshold, so the question of a contribution does not arise. National policy provides that affordable housing should not be sought from developments of ten dwellings or fewer with a gross floorspace of no more than 1,000m², with a lower threshold of five units available to authorities in designated rural areas. A serviced plot development of four or six houses sits below that, and the self-build affordable housing exemption people search for is usually this threshold rather than a policy written for self-build at all.

Above the threshold the position changes, and the arguments are different from those on a speculative scheme. Where a larger development includes self-build plots, the plots themselves become the subject of the agreement rather than a thing the agreement exempts.

What national policy says about self and custom build

Two statutory duties sit behind the policy. The Self-build and Custom Housebuilding Act 2015 requires authorities to keep a register of individuals and associations seeking serviced plots in their area. The Housing and Planning Act 2016 then added a duty to give suitable development permissions to meet the demand on that register, measured over base periods.

Planning practice guidance expands on both, and the practical consequence for an applicant is that the register is evidence. An authority with unmet demand recorded on its own register is in a weaker position when it resists a serviced plot scheme on policy grounds, and in a stronger position when it asks a large developer to provide plots.

What national policy does not do is exempt self-build from affordable housing policy. There is no national exemption. Any relief comes from the threshold, from a local plan policy, or from a negotiated position on the particular scheme.

Whether contributions are sought at all

Four situations cover almost every case.

The third row is where most argument happens. A scheme of fourteen serviced plots sold to individuals has a cost structure a volume housebuilder would not recognise, since the developer sells land rather than completed homes and the sales values are not under their control. That belongs in the viability discussion with evidence rather than in an assertion that self-build is different.

An Affordable Housing Statement should set out the threshold position first, then the policy position, then any viability case, in that order. Officers reverse that order often enough that the argument gets muddled.

Serviced plots and plot passports

The 2015 Act defines a serviced plot by reference to access and services. A plot qualifies where it has access to a public highway and connections for electricity, water and wastewater, or where the authority expects those to be provided within a specified period.

That definition matters in the drafting of an obligation. A plot sold with an unmade track and no utility connections is not a serviced plot, and an obligation to provide "self-build plots" without the servicing standard spelled out produces exactly that outcome.

A plot passport is the other half of the arrangement. It is a short document issued with each plot setting out the developable footprint, the height limits, the materials palette, the parking provision and anything the permission or a design code requires. It is not a statutory instrument, and its usefulness depends on it being tied to the permission, usually through a design code approved by condition.

Buyers benefit from a passport more than developers do. It tells an individual what they can build before they commit, which shortens the reserved matters or householder application that follows.

Securing plots in a planning agreement

Where an authority wants plots delivered on a larger site, the obligation normally requires a stated number or proportion of plots to be laid out, serviced and marketed as self-build or custom build plots for a defined marketing period, with a fallback to open market sale if they do not sell.

Five drafting points decide whether the obligation works.

1. The servicing standard, stated by reference to the 2015 Act definition and to the specific connections.
2. The marketing period, long enough to be meaningful and short enough to be commercially survivable. Twelve months from practical completion of the services is a common landing point.
3. The marketing method, including where the plots must be advertised and whether the authority's register must be notified.
4. The fallback, drafted so it operates automatically on evidence rather than requiring a further approval.
5. Phasing, so plots are not all released in the final phase when the scheme is already built out.

Without a fallback, a developer carries open-ended risk on land it cannot sell, and authorities generally accept that point when it is put with the marketing evidence attached.

The levy exemption and how it interacts

The Community Infrastructure Levy Regulations 2010 provide an exemption for self-build housing, together with exemptions for residential annexes and extensions. The exemption is claimed by the individual who will occupy the dwelling, has to be claimed and granted before development begins, and is withdrawn if the claimant does not occupy the dwelling as their sole or main residence for the required period or disposes of it within that period.

Three things trip people up. The claim is sequential, with a second stage after completion supported by documentary evidence, and missing a deadline voids the relief. The exemption belongs to the self-builder, not to the developer who sold the plot, so a plot sale needs to tell the buyer what they must do and when. And the exemption does not touch affordable housing obligations, which are secured by agreement rather than by the levy.

Where plots are sold to individuals, a short note handed over at completion explaining the claim sequence prevents the commonest and most expensive mistake on a self-build scheme.

Evidence of demand from the local register

The register is the applicant's best evidence and it is underused. Authorities publish the number of entries, usually by base period, and some publish plot size and location preferences.

Use it directly. State the number of entries at the most recent base period, the number of permissions the authority has granted that it counts towards the duty, and the gap between them. Where the authority has not demonstrated that it is meeting demand, that is a material consideration in favour of the scheme and it should be in the planning statement rather than in a covering letter.

Also check whether the authority applies a local connection or financial solvency test to its register, because those tests reduce the recorded demand and an authority relying on a low figure should be asked whether its own eligibility rules produced it.

Where authorities treat the scheme as ordinary housing

This is the risk that costs the most. A custom build scheme assessed as if it were speculative housing attracts the full policy package: affordable housing calculated on completed values, space standards applied to plots where the buyer has not yet designed anything, and a section 106 drafted for a single developer building out in one programme.

Head it off with three things in the submission. A clear description of the delivery model, including who builds what and in what sequence. A design code that answers the design control question the authority would otherwise answer through conditions on each plot. And an appraisal reflecting land sales rather than housing sales, with the inputs evidenced.

Where space standards or accessible housing requirements are applied, their effect on a plot-sale model is different from their effect on a conventional appraisal, and we set that out in space standards and accessible housing as appraisal inputs. If viability is the route you are taking, the submission format matters as much as the arithmetic, which we cover in viability appraisal outputs and what to submit, and a Viability Assessment for a plot-sale scheme should state its land value basis on the first page. Councils normally expect that work from a suitably qualified author, and professional review of any draft is strongly advised.

And keep the register evidence current. A figure two base periods old is the easiest thing for an officer to set aside.

Enter your postcode on PlanScope to see which reports a serviced plot scheme is likely to need.

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.