A side extension can dramatically increase your living space — adding a kitchen, utility room, playroom, or extra bedroom to the side of your home. Under permitted development rights, many homeowners can build a single storey side extension without planning permission, but the rules are specific and worth understanding before you start.
Yes, in many cases. Single storey side extensions are covered by Class A of Schedule 2, Part 1 of the Town and Country Planning (General Permitted Development) (England) Order 2015 — the same legislation that covers rear extensions. Provided your extension meets all the conditions, no planning application is needed.
Note: Double storey side extensions always require planning permission — there is no permitted development route for a two-storey side extension.
To qualify as permitted development, a single storey side extension must meet all of the following conditions:
The maximum width is half the width of the original house. This is measured from the original house as built — not including any existing extensions.
For example:
If your home is in a conservation area, National Park, Area of Outstanding Natural Beauty, or World Heritage Site, you cannot build a side extension under permitted development. Any side extension in these areas will require a full planning application.
This is one of the most important distinctions — conservation area restrictions on side extensions are stricter than for rear extensions.
While not compulsory, a Lawful Development Certificate (LDC) is strongly recommended. It provides formal written confirmation from your local planning authority that the extension was lawful under PD rules — which is particularly useful when you come to sell the property, as solicitors and mortgage lenders will often request proof.
Even without planning permission, you’ll need full architectural drawings for building regulations approval and for your builder to quote and work from accurately. Our side extension drawing packages include everything required — floor plans, elevations, and structural details — available as instant downloads.
No. Double storey side extensions are not permitted development and always require a full planning application.
Yes. Materials used in the extension should be similar in appearance to those used in the existing house. This is a condition of permitted development.
Yes, an L-shaped or wrap-around extension is possible under PD, provided both the side and rear elements individually comply with their respective permitted development rules.
Yes. Side extensions are not permitted development in conservation areas, National Parks, or Areas of Outstanding Natural Beauty. You will need to submit a full planning application.
Maximize your property’s footprint with precision and ease. Permitted provides complete design for Permitted Development Rights, ensuring your project meets all national requirements while bypassing the lengthy full planning permission process.
