In England Class D of Part 1 permits a porch outside any external door of a house if its external ground area is no more than 3 square metres, no part is over 3 metres high and no part is within 2 metres of a boundary with a highway, whereas a conservatory is normally assessed as an enlargement under Class A, which is not permitted beyond a wall forming the principal elevation.

Two classes, two rulebooks

Homeowners sometimes ask whether a glazed structure at the front door is a porch or a conservatory. The distinction matters because the permitted development rules for England, in Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015, treat them differently. GOV.UK’s technical guidance explains that Class A covers enlargement, improvement or alteration of a house, such as rear or side extensions, and Class D covers the erection of a porch outside an external door. This guide covers England; the position in Wales and other nations differs, and the Planning Portal notes that its guidance relates to England.

What Class D allows

Class D permits the erection or construction of a porch outside any external door of a dwellinghouse. Paragraph D.1 says development is not permitted if:

• the ground area, measured externally, would exceed 3 square metres;
• any part would be more than 3 metres above ground level;
• any part would be within 2 metres of any boundary of the curtilage that adjoins a highway;
• the house was granted use as a dwellinghouse only by virtue of certain Part 3 change-of-use classes, or was built under Part 20 (new dwellinghouses).

The Planning Portal adds that the allowances apply to houses and not to flats and maisonettes, and that a planning condition, an Article 4 direction or another restriction may remove them. Our guide to Article 4 directions explains how that works.

Why a front conservatory is different

A conservatory that extends the house is normally assessed under Class A. Paragraph A.1(e) says development is not permitted if the enlarged part would extend beyond a wall that forms the principal elevation of the original house, or that fronts a highway and forms a side elevation. GOV.UK’s technical guidance describes the principal elevation as usually the front of the house, and only one elevation is the principal elevation. A conservatory at the front is therefore generally outside Class A, while a porch within the Class D limits is a separate right. Class A also bars a raised platform, as our guide to the 0.3 metre rule sets out. The general rules for extensions are explained in our guide to permitted development and conservatories.

What if the porch is too big

A structure that exceeds a Class D limit does not benefit from Class D. A large glazed entrance structure at the front that also lies beyond the principal elevation cannot rely on Class A either, so it would need planning permission unless another right applies. Our guide to householder applications describes the process, and a lawful development certificate can confirm a scheme that is within the rules, as explained in lawful development certificates.

Building regulations for a porch

Planning permission and building regulations are separate. The Building Regulations 2010, Schedule 2, Class 7 exempts the addition at ground level of a conservatory or porch with a floor area not exceeding 30 square metres, provided any glazing satisfies the stated requirements. The Planning Portal says a porch at ground level and under 30 square metres is normally exempt, provided glazing and fixed electrical installations comply, the front entrance door between the house and the porch remains in place, and, where the house has ramped or level access for disabled people, the porch does not adversely affect it. It stresses that the 3 square metre planning limit is separate from the 30 square metre building regulations limit. Glazing is discussed in our guide to safety glazing.

FAQs

How big can a porch be under permitted development in England?

Class D limits a porch to 3 square metres of external ground area, 3 metres in height and a position no closer than 2 metres to a boundary that adjoins a highway.

Can I build a conservatory at the front of my house without planning permission?

Class A does not permit an enlarged part to extend beyond a wall forming the principal elevation of the original house, so a front conservatory generally needs planning permission unless another right applies.

Does the 3 square metre porch limit apply to building regulations?

The Planning Portal says the 3 square metre planning limit is separate from the 30 square metre limit in the building regulations exemption.

Do these rules apply to flats?

The Planning Portal says the porch allowances apply to houses and not to flats and maisonettes.

The bottom line

A porch and a conservatory are judged under different classes in England: Class D allows a small porch of up to 3 square metres and 3 metres in height that is at least 2 metres from a highway boundary, while a conservatory that extends the house is tested under Class A, which does not permit enlargement beyond the principal elevation. Building regulations are separate again, with a 30 square metre exemption for both. This is general information, not planning advice; confirm the position with the local planning authority.

Sources

This guide draws on the following primary sources, current as of 24 September 2026:

• legislation.gov.uk, “The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1: Development within the curtilage of a dwellinghouse”
• GOV.UK, “Permitted development rights for householders: technical guidance”
• Planning Portal, “Porches: Planning permission”
• Planning Portal, “Porches: Building regulations”
• legislation.gov.uk, “The Building Regulations 2010, Schedule 2: Exempt buildings and work”

Related guides

Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.