Can I replace windows on a listed building with double glazing?

Replacing original windows on a listed building requires Listed Building Consent and is carefully scrutinised. Standard UPVC or aluminium double-glazed windows are almost never acceptable on a listed building. Where replacement is agreed as necessary (rather than repair), slimline double glazing in timber frames matching the original profile may be acceptable. Secondary glazing - which leaves the original window in place and adds a discrete inner layer - is often the preferred solution as it preserves the original fabric and can be removed without damage.

Can I repair rather than replace windows on a listed building?

Yes, and repair is almost always the preferred approach. Original timber windows in listed buildings are frequently repairable even when they appear to be in poor condition. A skilled joiner specialising in historic windows can splice in new timber, replace sash cords, reglaze individual panes and draught-proof the frame while retaining all the historic fabric. Repair also does not normally require Listed Building Consent (if it is genuinely like-for-like), unlike replacement which always does. A repaired original window often outperforms a replacement in thermal performance once properly draught-proofed.

Do I need Listed Building Consent to repaint windows on a listed building?

Repainting windows in the same colour does not normally require Listed Building Consent, as it does not affect the architectural or historic character of the building. Changing the colour of windows or doors may require consent where the building's list entry or a planning condition specifies a particular colour scheme. In conservation areas, changing the paint colour of external features may also be controlled under an Article 4 Direction. Always check with your local conservation officer if you are unsure.

Windows and Doors on Listed Buildings - Replacement and Repair Rules

Why Windows and Doors Matter So Much

Windows and doors are among the most significant features of any historic building. They define its character, mark its period, and contribute more to its appearance - internal and external - than almost any other element. For this reason, the Local Planning Authority and Historic England treat unauthorised window and door replacement as one of the most serious categories of harm to listed buildings.

The loss of original sash windows, panelled doors, original ironmongery and glazing bars is essentially irreversible. Once original fabric is removed, the building loses authenticity that cannot be recreated, only approximated.

UPVC window frames are never acceptable on a listed building. Standard aluminium frames are almost always refused. The only acceptable replacement materials are timber (matching the original) or, in some limited cases, slimline aluminium systems designed to replicate historic timber profiles.

Original Georgian sash windows with glazing bars on a Grade II listed townhouse - the type of window listed building consent protects — Original sash windows with slim glazing bars are among the most significant features of Georgian and Victorian listed buildings. Their repair and retention is almost always required.

Repair vs Replacement: The Hierarchy

Conservation policy is clear: repair is always preferred over replacement. The NPPF and Historic England's guidance establish a hierarchy for works to listed building fabric:

Repair in situ - using original or matching materials and methods. Does not normally require LBC if genuinely like-for-like.
Repair with partial renewal - splicing in new timber to decayed sections while retaining the original frame. Usually does not require LBC if like-for-like.
Like-for-like replacement - replacement of a window or door with one that exactly matches the original in material, dimensions, profile and glazing. Requires LBC. May be accepted where repair is genuinely not viable.
Replacement with change - any change in material, profile, glazing type or opening configuration. Requires LBC and is subject to significant scrutiny. UPVC is never acceptable; slimline double glazing in timber may be.

Consent Requirements Table

Works	LBC needed?	Notes
Repainting windows same colour	Usually not	Purely cosmetic - no consent if colour unchanged
Like-for-like repair (same material, profile)	Usually not	Genuine repair in situ; check with conservation officer
Like-for-like replacement (same material, same profile)	Yes - LBC	Affects building fabric; consent required
Replacement with slimline timber double glazing	Yes - LBC	May be acceptable; glazing bar profile must match
Replacement with UPVC	Yes - LBC + refused	Never acceptable on any listed building
Installation of secondary glazing	Likely yes	Affects interior character; check with conservation officer
New window opening	Yes - LBC	Affects external appearance and structure
Replacing front door with different style	Yes - LBC	Character impact; like-for-like less likely to be refused
Draught-proofing (brush seals, no fabric removal)	Usually not	Reversible; does not damage original fabric

Secondary Glazing: the Conservation Solution

Secondary glazing - adding a separate glazed unit to the room-side of an existing window - is widely used in listed buildings as a way of improving thermal and acoustic performance without affecting the original fabric. It offers several advantages:

The original window is preserved intact and undamaged
It is fully reversible - it can be removed without any damage to the building
It achieves comparable thermal performance to double glazing, especially when combined with draught-proofing of the original window
Acoustic performance can be better than replacement double glazing
It does not require listed building consent in most cases (though it is always worth checking with your conservation officer)

Slimline Double Glazing

Where replacement is the only option (for example where a window is beyond repair), slimline double glazing units using 4mm glass with a narrow cavity may be acceptable. The key requirements are:

The frame must be timber, matching the original in species, profile and dimensions
Glazing bars must match the original in width, section and position
The glass must not have visible coatings that change the reflectivity or appearance
The unit must be manufactured to match the existing opening exactly

This type of glazing cannot achieve the same U-values as modern double glazing in modern frames, but when combined with secondary glazing or draught-proofing, the overall thermal performance of a listed building can be significantly improved.

Building Regulations and Listed Buildings

Replacement windows in domestic buildings normally need to comply with Part L (energy efficiency) of the Building Regulations. However, listed buildings can apply for a relaxation of Part L requirements where compliance would unacceptably alter the character of the building. In practice, the requirement to use appropriate traditional materials almost always means that full Part L compliance is not achievable, and the LPA and Building Control work together to agree a reasonable standard.

Note that Building Regulations consent is separate from Listed Building Consent - both may be required.

Windows and Doorson Listed Buildings