Good news: most conservatories in England can be built under permitted development, meaning you won’t need planning permission — as long as you stay within the size limits. A conservatory is treated like a single-storey rear extension. Here’s what you need to know in 2026.
When you usually DON’T need planning permission
Your conservatory is likely permitted development if it meets all of these conditions:
- It is at the rear of the property, not forward of the principal elevation facing a highway.
- Depth is no more than 3m for an attached (terraced/semi) house, or 4m for a detached house.
- Maximum height is 4m (or no higher than the existing eaves if lower).
- It, together with other outbuildings, covers no more than 50% of the garden.
- You are not in a conservation area or building that has had permitted development rights removed.
When you DO need planning permission
You will need to apply for planning permission if your home is a listed building, if your permitted development rights have been removed by an Article 4 Direction, if the conservatory sits forward of the principal elevation, or if you want to exceed the size limits. Larger rear extensions (up to 6m attached / 8m detached) may be possible under the prior-approval “Larger Home Extension” scheme.
Don’t forget building regulations
Planning permission and building regulations are different things. Conservatories are often exempt from building regulations if they are under 30m², built at ground level, separated from the house by external-quality doors or windows, have independent heating controls, and use safety glazing. Remove the separating doors to knock through, and that exemption is usually lost.
Rules vary across the UK
Similar principles apply in Wales, Scotland and Northern Ireland, but the exact limits differ — always check with your local planning authority before you commit.
Compare conservatory quotes
Once you know what you can build, the next step is price. See our conservatory cost guide, and use the form above to get free quotes from trusted installers near you.