Child yield: calculating play space requirements

Child yield calculation planning work converts a unit mix into an expected number of resident children, then converts that number into a play space area requirement by age band. It is a two-step arithmetic exercise with local policy at both ends, and it is the figure that decides whether a scheme provides a doorstep play area, a full equipped playground, or a payment in lieu. Get the yield wrong at design stage and the layout has to change, because play space is a land take you cannot squeeze in afterwards.

The method is most developed in London, where the London Plan and Greater London Authority guidance set out a population yield approach and a provision benchmark per child. Outside London the principle is the same but the figures come from the local plan or an open space supplementary planning document.

What child yield estimates

Child yield is the expected number of children living in a development once occupied, broken down by age. It is a prediction, not a count, and the prediction rests on occupancy assumptions.

Two variables drive it. The size of the homes, measured by bedroom count, because larger homes house more children. And tenure, because social rented and affordable housing has consistently higher child occupancy than market housing of the same size.

That second point is where applicants and officers most often disagree. A scheme with a high proportion of three-bedroom affordable homes yields far more children than the same number of market one-beds, and the play space requirement follows. Which also means that reducing affordable provision reduces the play space requirement, a relationship nobody enjoys explaining at committee.

The yield figure also feeds other calculations: school place contributions, health infrastructure, open space and sometimes the Social Infrastructure Assessment on larger schemes.

Deriving it from unit mix and tenure

The calculation follows a fixed sequence, and the inputs have to come from a stated source.

1. Set out the unit mix as a schedule of accommodation, by bedroom count and tenure.
2. Apply the child occupancy rate for each unit size and tenure combination, from the policy source that applies locally.
3. Sum to give a total child yield for the scheme.
4. Split the total into the age bands the local policy uses.
5. Multiply each age band by the provision benchmark per child.
6. Sum to give the total play space area requirement in m².

The occupancy rates themselves are published. In London they come from the Greater London Authority's population yield calculator, which is the tool officers will use to check your figure. Outside London, check the open space or play space supplementary planning document, and where none exists, ask the authority which source it applies before you calculate anything.

A worked illustration. Take a scheme of 60 flats: 20 one-bed market, 20 two-bed market, 10 two-bed affordable rent and 10 three-bed affordable rent. Applying occupancy rates that rise with bedroom count and are higher for the affordable rented units, the three-bedroom affordable homes contribute a disproportionate share of the child yield despite being a sixth of the scheme. This example is illustrative and uses no specific published rates, because those rates differ by authority and are revised.

Age bands and the provision each needs

Play policy splits children by age because what they need differs completely.

The under-fives requirement is the one that shapes the layout, because it has to be within sight of the homes it serves. That rules out tucking it behind a bin store or on the far side of a car park. Overlooking from kitchen windows is a design requirement rather than a nicety.

Youth provision for the over-twelves is where off-site contributions are most often accepted, because a small infill scheme cannot sensibly provide a kickabout area and teenagers travel further anyway.

Converting yield into an area requirement

The conversion is a multiplication, but the benchmark differs by authority and sometimes by age band.

The London Plan approach uses a benchmark of 10m² of playable space per child, applied to the yield, with the expectation that under-fives provision is made on site. Outside London, authorities set their own figures in the local plan or a supplementary planning document, and some use a provision standard per thousand population rather than per child, which gives a different answer for the same scheme.

Three points that recur in negotiation:

Playable space is not the same as amenity space or landscaping. Space that counts has to be usable for play, which means it cannot be a steep bank, a drainage swale with standing water, or a strip of shrub planting.

Communal gardens can count where they are properly accessible to the children they serve and designed for play, but a podium garden with no play value will be challenged.

Double counting is the common error. An area cannot serve as the under-five doorstep space, the amenity space for the flats above and the biodiversity net gain habitat all at once, and an officer will ask which it is.

On site, off site and commuted sums

Where on-site provision falls short, the shortfall is usually resolved by a financial contribution secured through a section 106 agreement. The tests in the Community Infrastructure Levy Regulations 2010 apply, so the contribution has to be necessary to make the development acceptable, directly related to the development, and fairly and reasonably related in scale and kind.

In practice that means the authority has to identify the project the money will be spent on. A general contribution to a play budget with no identified scheme is vulnerable.

Where a Community Infrastructure Levy charging schedule is in place, the authority cannot normally seek a section 106 contribution for the same infrastructure item that the levy funds, so check whether play space is on the authority's levy infrastructure list before agreeing a contribution. That interaction is frequently missed and sometimes results in a developer paying twice.

The sequencing point: agree the yield figure before you negotiate the contribution, because the contribution is calculated from it. An argument about £40,000 of play contribution is really an argument about occupancy rates for four affordable three-bed homes.

Design standards for equipment and surfacing

Once the area is settled, the detail is governed by product standards rather than planning policy.

Play equipment is designed and installed to BS EN 1176, and impact-absorbing surfacing to BS EN 1177, with the critical fall height of each item determining the surfacing specification beneath it. Those are the standards a council's play officer will cite, and getting the surfacing specification right is a cost item worth pricing early because wet-pour surfacing is expensive per square metre.

Other design points that come up in conditions:

• Inclusive design, so that equipment and surfacing are usable by disabled children, which connects to the public sector equality duty under the Equality Act 2010.
• Natural play features, logs, boulders and planting as an alternative to catalogue equipment, which many authorities now prefer.
• Shade and seating for supervising adults.
• Fencing and gating where the space adjoins a road or a watercourse.
• Surface water drainage, so the space is usable after rain.
• Lighting, balanced against the amenity of adjoining homes and obtrusive light guidance.

Management and maintenance obligations

Play space carries a long-term liability, and the planning obligation will say who holds it.

The three routes are adoption by the local authority, usually with a commuted maintenance sum; management by a management company funded through an estate charge on residents; or retention by a registered provider where the space sits within affordable housing. Each has consequences for the service charge and for the sales position, so decide early.

Inspection regimes follow the equipment standards, with routine visual, operational and annual main inspections, and the records are what a claim turns on. A management plan secured by condition or obligation should name the inspection frequency, the responsible party and the replacement provision for equipment at end of life.

Fix the yield, fix the area, then fix the maintenance route. In that order, because each depends on the one before. The report index shows which open space and social infrastructure documents accompany a residential application, and the play space assessment page sets out what that document covers.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance rather than legal advice. Occupancy rates and provision benchmarks are set locally and revised, so check the current adopted figures with your local planning authority before relying on any calculation.