A small porch outside an external door of a house may qualify as permitted development in England. The measurements concern the proposed structure and its position, not just the space available inside it.
What are the main porch limits?
The externally measured ground floor area must not exceed 3 square metres. No part may rise more than 3 metres above ground level, and no part may be within 2 metres of a boundary that fronts a highway.
These rights apply to qualifying houses, with exclusions and possible restrictions. They do not apply to flats or maisonettes. Check the Planning Portal's porch guidance for the complete context rather than treating the three measurements as the whole assessment.
How should you measure the proposal?
Prepare a simple plan showing the outside faces of the walls and the surrounding boundaries. Include the front path, pavement and road, then mark the proposed height on an elevation. If ground levels slope, flag that for assessment rather than choosing whichever measurement produces the smallest figure.
A builder's internal floor area may not answer the planning question. Ask for the external dimensions and confirm what the proposed roof and entrance arrangement will look like. Photographs of the entrance and street frontage help explain the setting.
What if you want more than a porch?
Describe the actual space you need. A larger entrance hall, additional room or extension should be assessed on its own proposal, rather than labelled a porch to fit a smaller allowance. Our side extension guide explains another common route, but the location of the work matters.
Find your planning authority and check earlier permissions for relevant conditions. If an Article 4 direction affects the property, read the rights and area it specifies rather than assuming every alteration is restricted.
What is the next step?
Start with the permitted development checker. For formal evidence that a qualifying proposal is lawful, read about a lawful development certificate.
Building regulations have a separate assessment, including conditions for any porch exemption. Check the Planning Portal's building regulations guidance before construction; meeting planning limits does not settle every building control requirement.