Sources and method
A page that tells you what planning law says is only worth reading if you can check it. These are the 32 sources this site is built on, and the rules applied in reading them.
Method
- Statute first. Any question about whether permission is needed starts with the Act or the statutory instrument on legislation.gov.uk, in its latest revised form, amendments tab included. Several of the provisions below have been amended more than once, and secondary commentary frequently describes a repealed version.
- Then national policy and guidance — the National Planning Policy Framework and Planning Practice Guidance in England, and the equivalents in the other nations. These are not law, but they are what officers apply.
- Then heritage technical advice from Historic England, Historic Environment Scotland and Cadw, for the question of what is likely to be acceptable as opposed to what is legally required.
- Then local policy. Because the practical answer is local, real published authority guidance, conservation area appraisals and Article 4 directions are read and quoted directly rather than generalised from.
- Everything is dated. Each page carries the date its content was last checked against its sources, and pages are re-checked on a schedule.
- Conflicts are shown, not smoothed over. Local authority guidance sometimes contradicts the statutory position — most often by describing a consent that is no longer required. Both are reported, with an explanation of which is which.
Legislation — England and Wales
The statutory foundation. legislation.gov.uk shows the "latest available (revised)" text; check the amendments tab, because several of these have been amended repeatedly.
- Town and Country Planning Act 1990, section 55
Defines "development" — and excludes alterations that do not materially affect a building’s external appearance. The provision that decides whether window work needs permission at all.
- Town and Country Planning Act 1990, section 171B
Time limits for taking enforcement action.
- Levelling-up and Regeneration Act 2023
Amends the enforcement time limits in section 171B for England.
- Planning (Listed Buildings and Conservation Areas) Act 1990, sections 7 and 9
Listed building consent: the requirement, and the offence of carrying out works without it.
- Planning (Listed Buildings and Conservation Areas) Act 1990, section 66
The duty to have special regard to preserving a listed building and its features of special interest when deciding applications.
- Planning (Listed Buildings and Conservation Areas) Act 1990, section 72
The duty to pay special attention to preserving or enhancing the character and appearance of a conservation area. The hook for most window refusals.
- Enterprise and Regulatory Reform Act 2013, section 63 and Schedule 17
Abolished conservation area consent in England and replaced it with planning permission for relevant demolition. Commenced 1 October 2013 by SI 2013/2227. Widely mis-cited as section 60, which is a different provision about listed building consent orders.
- Town and Country Planning Act 1990, section 196D
The offence of failing to obtain planning permission for "relevant demolition" in a conservation area in England — the control that replaced conservation area consent. It concerns demolition, not alteration.
- Historic Environment (Wales) Act 2023, sections 161–162
Conservation area consent in Wales, which still exists but has been granted under this Act rather than the 1990 Act since 4 November 2024. It too covers demolition only.
- Town and Country Planning (General Permitted Development) (England) Order 2015
Permitted development rights in England. Article 2 defines "dwellinghouse" (excluding flats); article 4 is the direction-making power; Schedule 2 Part 1 covers alterations to a house.
- GPDO 2015, Schedule 2, Part 1
The classes of permitted development for a dwellinghouse, and their limitations.
- GPDO 2015, article 4
The power to withdraw permitted development rights locally.
- Building Regulations 2010
Regulation 2 defines a "controlled fitting"; regulation 20 covers self-certification by competent persons; regulations 21–23 cover energy efficiency requirements in existing buildings.
National policy and guidance — England
Policy and guidance are not law, but they are what decision-makers apply, and Planning Practice Guidance is regularly updated. Always check the "updated" date on the page.
- National Planning Policy Framework
National policy, including the chapter on conserving and enhancing the historic environment.
- Planning Practice Guidance: historic environment
Government guidance on conservation areas, designation, appraisals and the management of change.
- Planning Practice Guidance: when is permission required?
Government guidance on development, permitted development rights, and Article 4 directions — including when authorities should make them.
- Approved Document L: conservation of fuel and power
The energy-efficiency standards replacement windows must meet, and the special considerations for historic and traditional buildings.
- Planning Portal: doors and windows
The government-endorsed plain-English summary for householders.
- Planning Portal: conservation areas
What conservation area designation changes for a householder.
Heritage guidance
The national heritage bodies publish technical advice rather than rules. Local authorities lean on it heavily, so it is worth reading before you design a proposal — but note that none of these bodies "approves" or certifies commercial products.
- Historic England: repair or change windows in an older home
The homeowner-facing starting point on window repair and replacement.
- Historic England: modifying historic windows when retrofitting
The central technical advice on draughtproofing, secondary glazing, slim double glazing and vacuum glazing in historic windows.
- Historic England: secondary glazing for windows (HEAG085)
Detailed guidance on specifying secondary glazing in historic buildings.
- Historic England: conservation area consent
What the abolished consent covered, and what replaced it.
- Historic Environment Scotland: guidance and publications
Technical papers and short guides, including measured thermal performance of upgraded traditional windows.
- Cadw: conservation areas
The Welsh position on conservation areas and works within them.
Scotland, Wales and Northern Ireland
Different legislation, different permitted development classes, different consent names. English guidance is not a safe guide in any of the three.
- Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997, s.66
Conservation area consent in Scotland, which — unlike England — still exists.
- Town and Country Planning (General Permitted Development) (Scotland) Order 1992, Schedule 1
Permitted development classes in Scotland, including the householder classes.
- Scottish Government Circular 1/2024: householder permitted development rights
The current official interpretation of the Scottish householder classes.
- Scottish Government: guide to conservation areas in Scotland
Designation, consent and the effect on householders in Scotland.
- Planning Portal Wales: conservation area consent
The Welsh consent regime for demolition in conservation areas.
- Planning Act (Northern Ireland) 2011
The statutory framework for planning and conservation areas in Northern Ireland.
- Planning (General Permitted Development) Order (Northern Ireland) 2015
Permitted development rights in Northern Ireland.
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