Porch permitted development is class D of the householder classes: a porch outside any external door of a house, allowed without an application provided its ground area, measured externally, is within the limit the order sets, no part of it is higher than the height limit, and no part is within a distance of a boundary with a highway. It is the smallest right in the order and one of the most often exceeded, because a porch a little larger than the limit is not a porch under the class but an extension under class A, read against the front elevation rule that forbids an extension forward of the principal elevation. Permitted development porch reads the same on a detached house and a terrace, does not depend on the curtilage and is available on designated land, and it is a right a developer reads on a house whose front door opens straight onto the street. This page sets out the class as the developer reads it.
The three limits, and how they are measured
The ground area is measured externally, so the walls count and a porch drawn to the limit internally is over it; the height is measured from the ground to the highest part; and the distance is from the porch to any boundary of the curtilage with a highway, not to the road itself. All three must be met, and the order cited below states the figures. The porch does not count against the half-curtilage limit in the way extensions and outbuildings do, but a porch over the area limit becomes an extension and then does.
When the porch is an extension, and the front elevation
A porch beyond the area or the height is an enlargement of the house under class A, and class A does not allow an extension forward of the principal elevation or a side elevation fronting a highway, so a large porch on a front door facing the street needs planning permission. A porch on a side or rear door beyond the class D limits may be read as a side or rear extension instead, within those classes' own limits, and the envelope sheet on this site reads the rear and side envelopes for that case.
Designated land, article 4 and what the file keeps
Class D applies on designated land, which makes it one of the few rights a conservation area does not remove, but an article 4 direction can withdraw it and many conservation areas have one covering front elevations. The authority's constraints map and its article 4 schedule say whether the direction exists, and Curtilo Pro keeps the porch reading against the plot with the direction read on the day; the technical guidance cited below carries the diagrams.
Questions people ask about porch permitted development
How big can a porch be under permitted development?
Within the ground area limit measured externally, within the height limit, and not within the set distance of a highway boundary. The order cited below states the figures; a porch beyond them is an extension and needs an application on a front elevation.
Is a porch allowed in a conservation area?
Yes under class D unless an article 4 direction has withdrawn it, which is common on conservation area front elevations. The authority's article 4 schedule says.
Does a porch need building regulations?
Not if it is at ground level, within the area limit, separated from the house by the existing door and its glazing and electrics comply, which is the usual exemption; a porch beyond that is subject to the regulations.
Sources
- legislation.gov.uk, The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2 Part 1: the householder classes, the extension depths and widths, the outbuilding and porch limits and what designated land removes
- GOV.UK, Permitted development rights for householders: technical guidance, the government's reading of Part 1 with diagrams of the original house, the rear and side limits and designated land
- GOV.UK planning practice guidance, When is permission required: development, permitted development rights, prior approval and article 4 directions