Back-to-back distances and privacy standards

The back to back distance planning standard most English councils apply is 21 metres between facing habitable room windows, with around 10.5 metres from a habitable room window to the rear boundary. Neither figure appears in national policy. They come from local design guidance, they vary between authorities, and they are rules of thumb that stand in for a judgement about privacy rather than tests with a technical basis.

Knowing that is what lets you argue about them sensibly. An officer applying 21 metres is applying their council's guidance in support of a local plan policy on amenity, and the policy is about actual loss of privacy.

Where separation standards come from

The 21 metre figure is roughly 70 feet, which is the giveaway. It entered local authority practice decades ago, and the usual explanation offered for it is the distance beyond which facial expressions cannot readily be distinguished, so that mutual overlooking stops feeling intrusive.

That explanation is folk memory rather than published research, and nobody defending the figure at appeal relies on the physiology. What the figure has is longevity and consistency: it has been applied across thousands of decisions, most housing built since the 1970s reflects it, and it produces a predictable suburban grain.

The status is straightforward. A separation distance in a supplementary planning document or design guide is guidance supporting a development plan policy. It is a material consideration, it is not a standard in any regulatory sense, and the policy is what an application is refused under.

So a breach is the start of the conversation. The question the decision-maker has to answer is whether unacceptable loss of privacy would result on this particular relationship.

Typical distances in adopted design guidance

Treat every figure in that table as an example of what authorities commonly adopt rather than a national rule, and read the council's own document. Some authorities apply 20 metres, some 22, some express the requirement as an angle rather than a distance, and a few have removed numerical distances altogether in favour of a design-led assessment.

Also check what counts as a habitable room. Living rooms, dining rooms, bedrooms and kitchens used as habitable space are normally included, while bathrooms, halls, landings, stores and utility rooms are not. A scheme that fails on a distance to a bathroom window has usually mismeasured the requirement.

Window to window against window to boundary

The two standards do different work and they are often confused in applications.

Window to window controls the relationship between two dwellings. It is the one neighbours raise and the one that matters most where the facing property already exists.

Window to boundary controls what happens next. Where a rear garden is shallow, a scheme meeting the boundary distance leaves room for the neighbouring plot to be developed to its own boundary distance without either breaching the window to window figure. It protects the future position rather than the present one.

That distinction matters on infill sites. A proposal on a deep plot may satisfy the full window-to-window distance against the existing house behind and still fail the boundary standard, because the officer is protecting the developable depth of the adjoining garden. The answer is usually to argue the point on the merits of the actual relationship, with evidence about the adjoining plot's realistic capacity.

Where the boundary is not the neighbour's garden but a road, a railway, a watercourse or a public open space, the boundary standard generally does not bite in the same way, because there is no prospect of a facing window.

Level changes and how they alter the judgement

A metre of level difference can matter more than three metres of distance.

Where the proposed building sits above the neighbouring property, its windows look down into the neighbour's garden and ground floor rooms, and the same separation distance produces a materially worse relationship. Where it sits below, the relationship improves, because sight lines from the lower building meet the upper building's wall rather than its windows.

Authorities handle this in different ways. Some require an additional distance for each metre of level difference, some deal with it as a matter of judgement, and some say nothing at all, which leaves the argument to the drawings.

Section drawings settle it. A cross-section through both properties at the critical relationship, with sight lines drawn from the proposed window at seated eye height and standing eye height, shows exactly what can be seen. Officers accept sections and argue with assertions, and this is one of the places where two extra drawings change a recommendation.

Oblique views and screening

Separation standards are written for direct facing relationships, and most real relationships are not direct.

Where windows are offset so that the view from one falls across the corner of the other, the intrusion is much lower, and many design guides say the standard applies to directly facing windows only. Quantify it: state the offset in metres and the angle of view, and mark on the plan which windows actually see which.

Screening is where applicants overreach. Permanent built screening works: an obscure-glazed window, a fixed pane, a high cill above 1.7 metres from internal floor level, an angled oriel, a solid privacy screen on a balcony, a brise soleil that blocks the downward view.

Planting does not work as the primary answer. A hedge can die, be removed or be cut back, and it is bare for part of the year. Officers know this and will discount a case that rests on a line of pleached hornbeam. Use planting to improve a relationship that already works rather than to create one that does not.

Set out the mitigation in the Design and Access Statement as a schedule keyed to window numbers, and secure the important elements by condition rather than leaving them to the construction stage.

Higher density contexts and flexible application

In town centres, on brownfield sites and in tall building locations, applying a suburban separation distance produces an absurd result. Existing urban blocks routinely sit at 12 to 18 metres across a street, and nobody suggests demolishing them.

National policy on making effective use of land, the National Design Guide and the design chapter of the current National Planning Policy Framework, published on 17 August 2026, all point towards a design-led approach to site capacity rather than the mechanical application of numerical standards. London guidance goes further and discourages blanket separation distances in favour of assessing the specific relationship.

The practical consequence is that the argument in a dense context is different in kind. Instead of asking whether you meet 21 metres, show the prevailing pattern of separation in the surrounding blocks, with measured examples, and demonstrate that your relationship sits within it. Then deal with the specific windows that need treatment.

Evidence supporting a reduced distance

A submission that carries a reduced separation distance usually contains:

• a plan marking every affected window on both properties, numbered, with the actual distance and the offset stated for each pair
• sections through the critical relationships with sight lines at seated and standing eye height
• the room use of each affected window on both sides, evidenced from the existing property's approved plans where available
• a schedule of mitigation by window, distinguishing permanent built measures from landscape
• measured examples of the prevailing separation in the immediate context, where the site is urban
• confirmation of level differences from a topographical survey rather than assumed levels

Do not run a privacy argument through a daylight report. The two are separate considerations, and a Daylight and Sunlight Assessment or an Overshadowing Study answers light rather than overlooking. Mixing them invites the objection that neither has been addressed properly.

Design responses that satisfy officers

The ones that work are architectural rather than presentational.

Offsetting windows so that no pair faces directly. Placing the deep plan rooms on the exposed elevation and the bedrooms on the sheltered one. Using clerestory glazing with a high cill on the affected elevation. Angling a bay so the view is directed along the site rather than across it. Pulling the upper floor back so that its windows sit further from the boundary than the ground floor.

And the honest one: reducing the scheme. A fourth bedroom that creates a direct window-to-window relationship at 14 metres may be the reason a scheme is refused, and the cost of removing it is usually lower than the cost of an appeal.

Browse the full report index for the documents a scheme with amenity issues usually needs, or enter your postcode on PlanScope to see which reports your site is likely to trigger.

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.