Nationally Described Space Standard: what the figures mean

The nationally described space standard sets minimum internal floor areas for new homes in England, expressed as gross internal area against the number of bedrooms, the number of bedspaces and the number of storeys. A one bedroom one person home starts at 39 square metres, or 37 where a shower room replaces a bathroom. A one bedroom two person home is 50 square metres. From there the table climbs by bedspace and by storey, because stairs consume area that a flat does not lose.

It was published as a technical housing standard in March 2015 and it is deliberately short. What causes the arguments is not the table but how it applies: whether your council has adopted it, whether your scheme is caught, and how the area was measured on the drawings you submitted.

What the standard actually sets

Three requirements sit inside the document.

The first is the gross internal area by dwelling type. The table runs from one bedroom one person homes through to four bedroom eight person homes, with separate figures for one, two and three storey dwellings. The step between one and two storeys for the same bedspace count is substantial, and it catches designers who assume a house and a flat with the same schedule of rooms are the same size.

The second is minimum bedroom sizes. A double or twin bedroom must be at least 11.5 square metres, with at least one double at a minimum width of 2.75 metres and other doubles or twins at 2.55 metres. A single bedroom must be at least 7.5 square metres and at least 2.15 metres wide. A room that fails those figures cannot be counted as a bedroom, which changes the bedspace count and therefore the required area for the whole dwelling.

The third is built-in storage, which is included within the gross internal area rather than added to it, with the required amount rising as the number of bedspaces rises. Take the figures from the table rather than from memory, because this is the part most often got wrong.

There is also a height expectation: a floor to ceiling height of at least 2.3 metres over at least 75 per cent of the area.

Gross internal area, measured properly

Gross internal area is measured to the inside face of the external walls and includes internal partitions, circulation space, stairs, and built-in storage. It is not the sum of the room areas.

Two rules cause most of the errors. Areas with a headroom below 1.5 metres are excluded unless they are used for storage, which bites hard on rooms in the roof and on flats under a mansard. And the area includes the walls between rooms, so a plan with many small rooms and thick partitions delivers less usable space for the same compliant figure.

Put a schedule of areas on the drawings, unit by unit, with the bedroom areas and widths alongside the total. Case officers check this, and a schedule that they can read against the standard removes an entire round of correspondence. Where the scheme is large enough to need a Design and Access Statement, repeat the schedule there.

How a council makes it apply

The standard is an optional technical standard. A council adopts it by including a policy in its local plan, and national guidance expects that adoption to be supported by evidence of need, evidence that it will not undermine viability, and a reasonable transition period before it takes effect.

So the first question on any site is whether the standard is in the adopted plan and in what form. Some authorities apply it in full. Some apply it to particular development types. Some have a superseded policy setting different figures which continues to apply until the plan is reviewed. London boroughs apply the London Plan's own residential space standards alongside it.

Where the plan has adopted the standard, it is a policy requirement and a scheme falling short needs a justification the officer can carry through a report.

Where the plan has not adopted it, the standard still turns up in officer reports as a reference point for whether a unit provides acceptable living conditions. That is a weaker footing than policy, and an applicant can argue it. But a flat at 32 square metres is going to attract comment in any authority in the country, adopted policy or not.

Transition arrangements matter on sites with a long history. A scheme granted outline permission before adoption, coming forward at reserved matters afterwards, sits in an awkward position that the local plan's own transitional wording should resolve. Read it rather than assuming the position.

Where the figures come from

The standard was published as a technical housing standard in March 2015, following a review that consolidated a patchwork of local space standards into one national set. The figures were drawn from furniture layouts and activity space rather than invented, which is why the bedroom minimums correspond to a bed of a given size with circulation around it.

That origin is useful in argument. A room failing the single bedroom area is failing because a bed, a wardrobe and space to dress do not fit, and saying so is more persuasive than quoting the number back at a client.

Where the standard bites on conversions

Since April 2021 the standard has applied to new dwellings created through permitted development rights, without any need for local adoption. That is the rule that reshaped office to residential conversions, because it removed the possibility of very small units in deep plan buildings.

Conversions of houses into flats under full planning permission face the same discipline wherever the local plan has adopted the standard. Victorian and Edwardian houses divide awkwardly: the ground floor rear room becomes a bedroom of 10 square metres, the box room fails the single bedroom test, and the unit count drops by one.

Houses in multiple occupation sit outside the standard, since it applies to self-contained dwellings. Room sizes in licensed houses in multiple occupation are governed by separate licensing standards, and confusing the two regimes is a common error in feasibility work.

Practical consequences worth planning for

Three points repeat across schemes.

A room that is 11.2 square metres is not a double bedroom for the purposes of the standard, however it is labelled on the plan. Marketing language does not change the classification, and an officer will reclassify it.

Compliance is assessed on the approved drawings, so a design change during construction that shaves a bedroom below the threshold is a departure from the permission. Where the change is needed, a section 73 application to vary the approved plans condition is the orderly route rather than hoping the difference goes unnoticed at building control.

And bedspace counts drive the area, so adding a fourth bedspace to a two bedroom flat by making the second bedroom a twin increases the minimum area for the whole unit. Decide the schedule of accommodation before the plan is fixed, not after.

The standard is a floor rather than a target. Local plan policies on private amenity space, dual aspect, cycle storage and daylight sit alongside it, and a scheme that meets the areas but fails those will still be refused. You can check the supporting documents a housing scheme needs against your own proposal, and Enter your postcode on PlanScope to see which constraints apply to the site.

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.