Roof terraces, privacy screens and conditions

Roof terrace overlooking planning objections are won and lost on drawings, not on argument. There is no national separation distance for a terrace, no British Standard for a privacy screen and no numerical test an officer can apply. What there is, in almost every adopted local plan, is a policy requiring development to protect the amenity of neighbouring occupiers, and a case officer who has to decide whether a raised outdoor space will cause harm. Give them a sightline drawing, a screen specification and a condition they can impose, and the objection usually loses its force.

A terrace is also not permitted development on a house. Part 1 of the General Permitted Development Order excludes balconies, verandas and raised platforms, and a raised platform means one more than 0.3 metres high, so a flat roof terrace needs an application whatever its size.

Why roof terraces attract objections

Three things make a terrace feel different to a window. It is occupied for long periods rather than glanced through. It is used in good weather, when neighbours are also outside. And people on it can see downwards into gardens that were previously private from every angle except a first floor window.

Officers respond to that. The complaint they take most seriously is not the view into a bedroom, which a curtain solves, but the loss of a private garden, where the neighbour has no defence. On a terrace at second floor level looking over a 12 metre rear garden, the whole of that garden is visible, and no separation distance in the local design guide addresses it because those distances were written for windows.

The other pattern worth knowing is that objections cluster around the sense of being overlooked rather than actual overlooking. A screen that removes the sightline also removes the perception, which is why the screen does more work than the geometry.

Sightline analysis from terrace level

The analysis that convinces is a plan and a section together, not one or the other.

On plan, set an eye position 1 metre back from the balustrade line at each corner and at the centre of the terrace, then draw lines of sight to each neighbouring habitable room window and to the near boundary of each neighbouring garden. Shade what is visible. On section, use an eye height of 1.6 metres above finished terrace level and draw the sightline over the proposed screen to show where it lands on the neighbour's land.

Three refinements make the drawing harder to argue with:

1. Show the existing baseline. If the neighbour's garden is already visible from an existing first floor window, say so and shade that too, because the assessment is about the change rather than the absolute condition.
2. Include oblique views. Most terraces are challenged on the diagonal sightline past the end of a screen, not on the perpendicular one.
3. Draw the neighbour's position, not just yours. A view from their patio doors towards your terrace edge is what they will describe at committee.

Where the terrace also raises daylight, sunlight or overshadowing questions for the neighbour, the sightline work sits alongside a Daylight and Sunlight Assessment rather than replacing it, and the two should use the same survey model.

Screen heights and materials

Two heights are in play and they are frequently confused. Guarding to prevent falls is a Building Regulations matter under Approved Document K, and 1.1 metres above the terrace surface is the usual minimum. A privacy screen is a planning matter and needs to be taller, because 1.1 metres stops nothing at standing eye height. Screens between 1.7 and 1.8 metres above finished terrace level are what officers normally accept, and the figure has to be measured from the terrace surface rather than from the structural slab.

Material choice then decides whether the screen is acceptable in appearance as well as in function:

• Obscure laminated glass reads lightly, keeps daylight into the terrace and shows dirt. It needs a stated privacy level.
• Perforated or expanded metal gives a directional screen and suits a contemporary elevation, though the perforation percentage has to be low enough to block views at an angle.
• Timber or aluminium louvres with blades angled downwards block the downward view while keeping the outward one, which is often the right answer on a terrace overlooking gardens.
• Solid render or brickwork works but reads as an enclosure and can cause a wind funnelling problem on exposed terraces, which is part of the wider argument covered in roof terraces, sunlight and wind comfort together.

Fixed is the operative word. A screen with an openable section is not a screen, and an officer who sees a hinge will condition it shut or refuse it.

Obscure glazing and its limits

Obscure glazing is specified by privacy level on the widely used scale of 1 to 5, and only the upper end of that scale gives real privacy. Level 3 and below is decorative patterning through which movement and outline remain visible, which is why a condition that says "obscure glazed" without a level is close to worthless.

Write the level into the drawing and into the proposed condition. The same discipline applies to any obscure glazed window forming part of the scheme, where the level and the extent of the opening light both matter.

Glass also has a maintenance life. A screen that depends on an applied film will be clear again in a decade, so specify integral obscuration rather than film if the condition is to mean anything in the long run.

Planting as a screening solution

Planting is supporting mitigation, not primary mitigation. An officer will accept a planter of pleached hornbeam as an improvement to the appearance of a screen and as a softening of the terrace edge. They should not accept it as the reason the terrace does not overlook, because plants are seasonal, they die, and the condition requiring their retention is among the hardest to enforce.

Where planting is part of the scheme, specify evergreen species, give the planter depth and irrigation, and set the mature height against the screen height so the two are consistent. Then treat the screen as the thing doing the work.

Conditions securing screens in perpetuity

The condition is the point of the exercise. Well-drafted wording does four things: it identifies the screen on an approved drawing, it fixes the height and the specification, it requires installation before the terrace is first used, and it requires retention thereafter.

Offer the wording in the submission. Something along these lines is normally accepted: the privacy screen shown on the approved drawing, to a height of 1.8 metres above finished terrace level and glazed to the stated privacy level, shall be installed before the roof terrace is first brought into use and shall be retained in that form thereafter. That gives the officer a condition which is precise, enforceable and directly related to the harm identified.

For flats there is no permitted development fallback to worry about, since Part 1 rights apply to dwellinghouses. For a house, consider whether the permission should also control later alterations to the screen, because replacing an obscure panel with clear glass would otherwise be a matter for enforcement rather than for prevention.

Drawings that settle the question

• A terrace plan at 1:50 showing the screen extent, balustrade line and eye positions used.
• Sightline plan with shaded visible areas, including the existing baseline.
• Two sections through the terrace and the nearest affected window and garden.
• An elevation showing the screen in context, at the same scale as the rest of the elevations.
• A screen specification note: height above finished terrace level, material, privacy level, fixing and whether any part opens.
• A view from the affected neighbour's principal window or patio door towards the terrace.

Put all six in the Design and Access Statement rather than leaving them loose in the drawing pack. Officers write their reports from the statement, and a screen justified in one place is easier to carry through to a condition. The related question of how far apart facing windows should sit, and how to justify a departure, is covered in overlooking and separation distance justification.

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This article is general guidance, not legal advice. Amenity standards and separation distances are set locally, so 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.