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side windows privacy rules

1.7m Rule and Checklist: Side Windows Privacy Rules for England

England checklist for side windows on single storey extensions: 1.7m rule, obscurity levels, ventilation and avoiding planning conditions.

The Extension Works 29 September 2026
1.7m Rule and Checklist: Side Windows Privacy Rules for England

1.7m Rule and Checklist: Side Windows Privacy Rules for England

Obscure glazed side window above floor level

If you are adding side-facing windows to a single-storey rear extension in England, the starting position is strict: upper-floor and roof-slope windows on a side elevation must be obscure-glazed and non-opening, unless the opening part sits at least 1.7 metres above the finished floor. Designated land or restrictive local policy can remove that permitted development right entirely. When in doubt, check with your local planning authority before finalising drawings.

TL;DR:

  • Side-facing windows on single-storey rear extensions in England must have obscure glazing of at least level 3, with openable parts sitting at least 1.7 meters above the internal floor.
  • When windows serve stairways or landings, the 1.7-meter rule is measured from the stair or landing directly below the window’s center.
  • On designated land or under certain local policies, permitted development rights are removed, requiring full planning permission for side windows regardless of glazing or size.
  • Designing for daylight and privacy can include high-level, angled, or textured glazing that meet the opacity and height requirements without sacrificing natural light.
  • Proper planning and glazing details should be specified early in drawings, including obscurity level and ventilation, to avoid delays at the application and building control stages.
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Table of Contents

What the law says about windows on side elevations

The Town and Country Planning (General Permitted Development) (England) Order 2015 sets the baseline rule under Class A and Class C conditions. Any window in a wall or roof slope that forms a side elevation, including upper-floor windows and those serving a loft, must be obscure-glazed. The openable section of that window must also sit at least 1.7 metres above the finished internal floor level, or it must be fixed shut entirely.

This condition applies regardless of whether the extension itself needs planning permission. A single-storey rear extension might comfortably fall within permitted development limits on size and depth, yet still trigger this glazing condition if it includes a side-facing window above ground level, such as in a room with a raised floor or a loft conversion above.

The rule stops applying automatically once you are on designated land, such as a conservation area, an Area of Outstanding Natural Beauty, or where an Article 4 direction removes permitted development rights locally. In those cases, side-facing windows and often the whole extension need a full planning application, and the council will assess privacy impact case by case rather than relying on the standard Class A and Class C wording.

What the law says about windows on side elevations — overview diagram

What obscure glazing and the 1.7 metre rule mean on your drawings

“Obscure glazed” is not a single fixed specification. Gov rates obscurity on a scale, typically running from 1 to 5, and a minimum of level 3 is normally expected to satisfy permitted development. One-way glass and reflective films do not meet this standard because they still allow a clear view through from one side under certain light conditions.

Obscure glazing scale showing level three threshold

The 1.7 metre measurement is taken from the finished internal floor level to the bottom of the openable part of the window, not the frame or the glazing unit as a whole. Where a window serves a stairway or landing, the measurement point is the stair or landing immediately below the centre of the window, which catches cases where a half-landing sits higher than the room floor below it.

Homeowners drawing up plans can specify glazing to a recognised manufacturer standard, such as a Pilkington privacy level, so the planning officer can check compliance without ambiguity. Two details are worth annotating clearly:

  • The obscurity level of the glass, stated as a number on the 1 to 5 scale.
  • Whether each pane is fixed shut or openable, and if openable, the exact height of the opening mechanism above finished floor level.

When planning permission or extra conditions still apply

Meeting the Class A and Class C wording does not guarantee an easy ride. Planning Portal guidance confirms that on designated land, side extensions and side-facing alterations often need a full planning application regardless of how the glazing is specified, because permitted development rights are reduced or removed there.

Away from designated land, local plan policies frequently address neighbour amenity directly, and planning officers can still request tighter conditions on windows if they judge that overlooking harm remains likely. A window’s proximity to a neighbour’s garden, patio or another habitable room window matters more than its technical compliance with the 1.7 metre rule. So does orientation: a side window facing directly along a shared boundary tends to draw more scrutiny than one angled away from neighbouring plots.

Larger windows, even when correctly glazed and fixed, can also prompt a council to ask for design changes at the application stage, particularly where the extension sits close to a boundary. Checking your council’s neighbour consultation process early avoids surprises once drawings are submitted.

Designing side windows that meet the rules without losing light

You do not need to sacrifice daylight to satisfy the privacy conditions. Several established options work within the rules while keeping a room livable:

  1. High-level or clerestory windows positioned well above eye height let light in without offering a sightline into neighbouring gardens.
  2. Fixed obscure-glazed panes below 1.7 metres satisfy the non-opening requirement outright and can be combined with an openable section higher up.
  3. Angled or splayed glazing redirects the view away from a neighbour’s boundary while still admitting natural light.
  4. Translucent or textured panels in a stairwell or landing give the required obscurity without the flat, frosted look some homeowners want to avoid.

Fixed and obscure-glazed windows cannot provide fresh air, so building control will expect a ventilation strategy that meets Part F, typically trickle vents built into the frame or a mechanical extract system. Windows also need to hit the U-value targets extensions in England must meet under Part L, so thermal performance has to be considered alongside the privacy specification, not after it. Building control guidance is explicit that replacement or new windows must meet both ventilation and thermal standards together, and skipping this step at design stage tends to cause delays at completion.

Pro Tip: Specify trickle vents on the same drawing as the obscure glazing detail, so building control and planning conditions are satisfied in one pass rather than two rounds of amendments.

Fences, hedges and blinds are sometimes proposed as an alternative to glazing conditions, but planners rarely treat them as sufficient on their own, since none of them are guaranteed to remain in place indefinitely.

How councils and inspectors judge overlooking in practice

A Planning Inspectorate appeal decision at Parsonage Road, Egham illustrates how this plays out. The inspector required obscure glazing to a Pilkington level 4 standard or equivalent, along with non-opening panes below 1.7 metres, to prevent both actual overlooking and the perception of being overlooked from a first-floor extension window. The decision treated that perception as a material planning consideration in its own right, separate from whether anyone could genuinely see into a neighbour’s space.

Inspectors weigh distance to the boundary, whether the window aligns directly with a neighbour’s amenity space, and the field of view the window would create. A window a few metres from a neighbour’s patio, angled straight at it, draws a firmer response than one set further back or angled obliquely.

The practical takeaway is that a marginal case tends to attract conditions rather than a refusal outright. Designing to the stricter glazing and fixed-pane standard from the outset avoids a second round of negotiation.

Your step-by-step checklist before finalising side window plans

Before your drawings go anywhere near a planning portal, work through this sequence:

  • Check with your local planning authority whether the site sits on designated land or is covered by an Article 4 direction.
  • Annotate each side window on your drawings with its obscurity level, whether it is fixed or openable, and the 1.7 metre measurement point.
  • Confirm ventilation provision, trickle vents or mechanical extract, on the same set of drawings that show the glazing detail.
  • Speak to affected neighbours before submission, since their objections often shape the conditions a council imposes later.
  • Submit a householder planning application if your permitted development status is unclear rather than assuming compliance and risking enforcement.

The neighbour consultation scheme that some councils run for larger single-storey rear extensions can also flag privacy concerns before you commit to a final design.

How we handle side window compliance on every project

Checking permitted development status for side-facing windows should happen at the design stage, not after submission. Specifying obscure glazing levels and ventilation details directly on the drawings can help coordinate with building control so the glazing and Part F requirements are resolved together rather than in separate rounds of queries. This can be combined with instant online quoting, live 3D modelling, and a fixed VAT-inclusive price for a project.

— Esskay

Let us manage the planning and glazing detail for you

Getting side window conditions wrong after submission means redrawing plans, resubmitting, and waiting again. Handling the design, the planning route, and the building control liaison in-house can ensure that glazing levels, fixed pane details and ventilation provisions are specified correctly the first time rather than corrected after a council query.

The Extension Works

That matters most for homes where side windows sit close to a boundary, since a managed process catches the Pilkington level and the 1.7 metre rule at drawing stage rather than at appeal stage. For mechanical extract options where a window has to be fixed shut, Simco Direct’s guide to bathroom extractor fans is a useful reference for ventilation choices.

Start with an instant quote for your single-storey rear extension and see the design, planning route and price before you commit to anything.

Where to check the detail yourself

For the full legal wording, see the Town and Country Planning (General Permitted Development) (England) Order 2015 and GOV.UK’s technical guidance. The Planning Portal’s single-storey extension guide covers designated land exceptions, and Building Regulations guidance for extensions explains what building control checks on completion. Always confirm Article 4 directions and local plan policy with your own local planning authority.

Sources

FAQ

Do side-facing windows always need obscure glass?

Upper-floor or roof-slope windows on a side elevation generally need obscure glazing under the Town and Country Planning Order, unless the opening sits at least 1.7 metres above the floor. Ground-floor side windows without an upper storey above them are not automatically covered by this specific condition, though councils may still raise privacy concerns separately.

What glazing level counts as obscure enough?

GOV.UK guidance points to a minimum of level 3 on the standard 1 to 5 obscurity scale, and one-way glass does not qualify. Some appeal decisions, including one at Parsonage Road, Egham, have required a higher level 4 standard where overlooking risk was greater.

Can I avoid obscure glazing by using a fence or hedge instead?

Planners generally do not accept fencing or planting as a substitute for obscure glazing because there is no guarantee either will be maintained or kept in place long term. Fixed, obscure-glazed panes remain the standard route to satisfying privacy conditions on side elevations.

Does my extension still need planning permission if the windows are compliant?

Not necessarily, since permitted development can cover a compliant single-storey rear extension even with correctly specified side windows. However, designated land, an Article 4 direction, or restrictive local plan policy can remove that right, in which case a full application is needed regardless of the glazing.

How does The Extension Works handle these rules on a project?

The Extension Works checks permitted development status and specifies obscure glazing and ventilation details on the drawings as part of its in-house design and planning service. This is covered within its fixed VAT-inclusive pricing for a single-storey rear extension, alongside a £499 booking fee to start the process.