Permission for a conservatory is not open-ended. Section 91 of the Town and Country Planning Act 1990 sets a start deadline, and later design changes follow set routes with their own limits.
In this guide
A planning permission for a conservatory carries a time limit, a list of conditions and, in practice, a set of approved drawings. Homeowners who delay the build, or change the design once the permission is in hand, can lose the benefit of it. This guide covers England, using the Town and Country Planning Act 1990 and the government’s planning practice guidance. It is general information, not planning advice, and the decision notice for the specific permission is the document that governs.
The start deadline
Section 91 of the Town and Country Planning Act 1990 provides that every planning permission is subject to a condition that the development must begin within the applicable period, unless the council directs a different period. The Act defines the applicable period as three years in England and five years in Wales. The period begins on the date the permission is granted.
Planning practice guidance says the standard time limit condition normally appears first in the list of conditions on the notice. Where permission was granted without that condition, section 91(3) deems it to apply. The same guidance confirms that a section 73 application cannot be used to extend the time limit for starting development, so the deadline cannot be renewed that way.
What counts as starting
Section 56 of the 1990 Act says that, for section 91 purposes, development is begun on the earliest date any material operation starts. A material operation includes any work of construction in the course of erecting a building, the digging of a trench that will contain the foundations or part of them, and laying an underground main or pipe to the foundations or to such a trench. For a conservatory, digging the foundation trench is therefore one of the operations that can start the clock. The foundation stage is explained in the guide to conservatory foundations.
Conditions on the decision notice
Planning practice guidance says conditions should meet six tests: necessary, relevant to planning, relevant to the development, enforceable, precise and reasonable in all other respects. A pre-commencement condition, which stops development beginning until something is done, must not be imposed without the applicant’s written agreement except in the circumstances set out in the Town and Country Planning (Pre-commencement Conditions) Regulations 2018. The guidance notes that such conditions include wording such as “no development shall take place until”.
Common householder conditions require matching materials or work in accordance with listed plans. A different kind of condition can remove permitted development rights, as discussed in the guide to planning conditions that remove permitted development rights. A fee of £89 applies to a request to discharge a condition on householder development, according to the April 2026 schedule described in the guide to conservatory planning fees.
Changing the design after permission
Planning practice guidance sets out the options. Where changes are fundamental or substantial, a new planning application is needed. For lesser changes there are two routes.
- Non-material amendment (section 96A). There is no statutory definition of non-material; the council must be satisfied the change is non-material in the context of the scheme. The applicant must notify anyone who owns land affected, who then have 14 days to make representations. The council has 28 days to decide, or longer if agreed in writing. There is no right of appeal against refusal, and the original permission still stands. The fee for householder development is £46.
- Varying a condition (section 73). This can make a material amendment, but only to conditions, not to the operative part of the permission or the description of development. A grant takes effect as a new, independent permission that sits alongside the original. The householder fee is £89.
Guidance adds that section 73 cannot be used if no condition lists the originally approved plans; a section 96A application can add such a condition first.
Practical checks before work starts
Planning practice guidance says development must take place in accordance with the permission and the conditions attached to it. The builder’s plans should therefore match the decision notice, and a change in size, glazing or roof form should be raised with the council before it is built rather than after. The position of a conservatory built without the right consent is explained in the guide to retrospective planning permission. See the guide to householder planning applications for how the decision is reached.
FAQs
How long does planning permission for a conservatory last in England?
Three years to begin development, under section 91 of the Town and Country Planning Act 1990. In Wales the period is five years.
Can the three-year deadline be extended?
Not through a section 73 application, according to planning practice guidance. A fresh application would be needed if the deadline passes.
Can I move the conservatory a little after permission is granted?
Only if the council agrees the change is non-material under section 96A, or approves a new application. There is no statutory definition of non-material.
What counts as starting the build?
Under section 56 of the 1990 Act, digging a trench that will contain the foundations, or laying an underground pipe to them, counts as a material operation, as does construction work on the building itself.
The bottom line
Planning permission for a conservatory in England must be started within three years under section 91 of the Town and Country Planning Act 1990, the deadline cannot be extended through section 73, and the conditions on the decision notice must be followed. Small design changes can go through a non-material amendment at £46, while changes to conditions use section 73 at £89. Matching the build to the approved drawings protects the permission.
Sources
This guide draws on the following sources, current as of 9 October 2026:
- Town and Country Planning Act 1990, sections 56 and 91 (legislation.gov.uk)
- Flexible options for planning permissions, planning practice guidance (gov.uk)
- Use of planning conditions, planning practice guidance (gov.uk)
- Planning fees: annual indexation from 1 April 2026, Ministry of Housing, Communities and Local Government (gov.uk)
Related guides
Planning application fees
Householder applications
Retrospective permission
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.