Do Sliding Doors Need Planning Permission?

Widening an opening to take a large sliding door is a structural matter as much as a planning one. A new or larger lintel is almost always required, sized by a structural engineer for the span and the loads above it, and building control will want to see and approve those calculations regardless of whether planning permission was needed for the elevation change.

• A structural engineer's calculation for the new lintel or beam.
• Confirmation of load paths above the opening, particularly where a chimney or upper floor bears nearby.
• Building control sign-off, either through full plans or a building notice.
• Coordination between the structural opening date and the sliding door's manufacturing lead time.

Even where no planning permission is needed, a new sliding door must meet Part L thermal performance and Part K safety glazing requirements, and the surrounding structural opening must satisfy building control. A FENSA or Certass registered installer can self-certify the glazing element of this, but structural changes to form or enlarge an opening are usually handled through a separate building control application. See our guide to building regulations for windows for the detail.

The answer for bifolding doors is the same as for sliding doors, and for the same reason: planning authorities are concerned with the change to the building, not with how the door operates. Replacing existing doors or a window with bifolds in an opening of the same size, on an unlisted house outside a conservation area, is normally permitted development and needs no planning application. Forming a new opening or widening an existing one — which most bifold installations do, because they are usually specified to open up a whole wall — is the point at which permission may be required.

• Like-for-like replacement with bifolds in the same opening: normally no planning permission needed on an unlisted house outside a conservation area.
• Widening the opening or forming a new one on a rear elevation: often permitted development, but confirm with your local planning authority before ordering.
• Bifolds fitted as part of a new rear extension: permission depends on the extension, not the doors.
• Listed buildings: listed building consent is required for bifolds regardless of the opening size.
• Conservation areas and Article 4 areas: check both separately, as permitted development rights may be restricted.

Bifolds do carry two practical differences worth noting. Because the leaves stack, the structural opening is usually wider than the one it replaces, so a new lintel and a structural engineer's input are more commonly needed than with a like-for-like slider. And the threshold detail matters more: a low or flush threshold in an existing wall often involves floor build-up work that building control will want to see. Neither affects planning status, but both affect cost and programme.

1. 01Establish whether the opening is changing sizeThis single fact determines most of what follows.
2. 02Check listed and conservation statusConfirm both separately, and any Article 4 direction, with your local planning authority.
3. 03Get a structural opinion early if the opening is growingA rough sense of feasibility and lintel cost should come before a full survey, not after.
4. 04Confirm building control routeDecide whether a full plans application or a building notice suits the project, in discussion with your installer or builder.

• Assuming a bigger sliding door can always simply replace a smaller window without checking planning status.
• Ordering a door before a structural engineer has confirmed the new lintel size and cost.
• Overlooking building regulations because planning permission was not required for the elevation change.
• Not checking Article 4 status where the property is in a conservation area.

Last reviewed September 2026.