Obscure glazing conditions and the levels that apply

An obscure glazing condition requires a named window to be fitted with glass you cannot see through, and usually to be fixed shut below 1.7 metres above the floor of the room it serves. It is the standard council answer to an overlooking objection on a householder application, and it appears on thousands of decision notices every year.

The condition normally specifies a level of obscuration on a scale of one to five, with five the most obscure, and requires the glazing to be retained for as long as the building stands. That last part is the bit people miss when they replace a window 15 years later.

Why councils impose the condition

Overlooking is a material consideration, and a case officer faced with a new first-floor window looking at a neighbour's bathroom has three options: refuse, ask for the window to be redesigned, or approve with a condition.

The condition is the quickest route to approval for everybody. It answers the objection, it can be drafted precisely, and it satisfies the tests in national guidance for the use of conditions, because it is necessary, relevant to planning, relevant to the development, enforceable, precise and reasonable.

Conditions of this sort are most common on side elevation windows at first floor, on landing and stair windows close to a boundary, and on any window serving a bathroom or a utility room where the loss of outlook costs the occupant little.

The one situation where a condition will not do is where the room is a habitable one and the outlook is part of what makes it habitable. Obscuring the only window in a bedroom is a poor outcome and officers know it, so a scheme that depends on it tends to be redesigned instead.

The obscuration levels and what they mean

Obscure glass is graded by how much it disrupts vision, on an industry scale running from one to five. Level one is lightly textured and you can make out shapes and movement clearly. Level five is heavily textured and gives near-total privacy while still passing light.

Most council conditions specify a minimum level rather than a product, commonly level three or above, with more sensitive relationships attracting level four or five. Read the condition wording rather than assuming, because the levels are not interchangeable and an officer checking compliance will ask for the specification.

Frosted film applied to clear glass rarely satisfies a condition. It is not permanent, it can be peeled off, and a condition requiring glazing to be obscure-glazed means the glass itself. Where a condition is already in place and film has been used, expect to be asked to replace the unit.

Applied textures, acid-etched finishes, sandblasting and integral patterns all count as obscure glazing where they achieve the specified level. Reflective or tinted glass does not, because it does not obscure the view at all in the dark.

The 1.7 metre rule and where it comes from

The figure comes from permitted development. Class A of the General Permitted Development Order 2015 allows a householder extension only if any upper-floor window in a side elevation is obscure-glazed and non-opening, unless the parts that open are more than 1.7 metres above the floor of the room. The same wording applies to roof enlargements under Class B.

Councils have borrowed the number into their conditions on full applications, so it now appears whether or not permitted development is involved.

Measure from the finished floor level of the room, not from the outside ground and not from the cill. A window set high in a stairwell can easily comply where the same window in a bedroom would not, because the floor levels differ.

The practical answer for ventilation is a top-hung or hopper light set above the 1.7 metre line, with the lower panes fixed. Check that against the escape window requirement in the building regulations before ordering, because a first-floor bedroom may need an openable escape window and the two requirements have to be resolved together rather than in sequence. The same tangle comes up when fitting a shower room into a loft conversion.

Offering the condition before it is imposed

If you can see the objection coming, put the answer on the drawings. Mark the window on the elevation as obscure-glazed to a stated level, with a note that opening lights sit above 1.7 metres from finished floor level, and add a window schedule.

Two things follow. The neighbour consultation response is weaker, because the mitigation is already in the submitted scheme. And the condition, if imposed, matches what you intended rather than what an officer drafted at speed on a Friday.

A short Planning Statement that names the affected window, the distance to the neighbouring window or garden, and the obscuration level offered, does the work of several rounds of correspondence. Where the relationship is tight and daylight is also in issue, a daylight and sunlight assessment can show that the obscured window is not the one carrying the room's light.

Discharging, varying or removing the condition

Most obscure glazing conditions do not need discharging, because they are worded as ongoing requirements rather than as something to be signed off in advance. Read the wording. A condition that requires details to be submitted and approved needs a discharge of conditions application before work starts, and one that simply requires the window to be obscure-glazed and retained does not.

Removing or changing the condition later means an application under section 73 of the Town and Country Planning Act 1990 to vary it, which is a fresh planning decision on that point. The neighbour will be consulted again, and the council will apply the same overlooking test it applied first time. If nothing has changed on the ground, nothing is likely to change in the answer.

What does sometimes change is the context. A new outbuilding, a matured hedge or a rebuilt boundary wall on the neighbouring side can remove the line of sight the condition was protecting, and that is an argument worth making with photographs and a section drawing rather than a letter.

What happens if the glazing is replaced

This is where householders get caught. A window replaced with clear glass breaches the condition, and a breach of condition can be enforced through a breach of condition notice, against which there is no right of appeal. Compliance means putting the obscure glass back.

Conveyancing picks it up too. A buyer's solicitor compares the decision notice conditions with what is on site, and a clear pane where the condition says obscure produces an enquiry, a retention or an indemnity policy.

The enforcement time limits for breaches of planning control in England were changed by the Levelling-up and Regeneration Act 2023, and the date on which that change took effect should be checked rather than assumed. Either way, a condition requiring retention continues to bind the land, so time limits are a poor thing to rely on.

Design alternatives that avoid the condition

Obscure glazing is a compromise, and there are usually better answers on the drawing board.

High-level clerestory glazing above head height gives light without a view out or in. A rooflight in a pitched or flat roof does the same and often daylights the room better than a side window would. Angling a window or forming a shallow oriel so the view is directed down the applicant's own garden works where the geometry allows it. Fixed external louvres or brise soleil can cut the oblique view while keeping clear glass.

And sometimes the answer is to move the room. Putting the bathroom on the elevation facing the boundary and the bedroom on the elevation facing the garden costs nothing at design stage and removes the issue entirely.

Draft the supporting statement for a householder application on PlanScope and have it reviewed before you submit.

This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that works are lawful, 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.