Pocket Doors for Extensions: How to Plan Them In From the Start

An extension is the best chance you’ll get to fit a pocket door properly. The walls are being built from scratch, so there’s no plaster to strip and no studwork to cut around. The catch is timing: a pocket door has to be designed into the wall before it’s built, not added once the plasterer has been.

This guide covers how to plan pocket doors for extensions, from the drawings to the day the door goes on.

Why extensions suit pocket doors

Modern extensions often join a new kitchen, dining or family space to the existing house. That creates new doorways in awkward places: between the old kitchen and a new utility, to a downstairs WC or boot room, or across a wide opening that you want to close off now and then.

A pocket door helps in a few ways:

• No swing. Doors don’t clash with kitchen units, islands or furniture in a busy open-plan room.
• Flexible layouts. A wide single or double pocket door lets you open a space up or close it off. Our guide to single vs double pocket doors compares the two.
• Clean lines. With a frameless kit, the opening can sit flush with the wall with no architrave, which suits a contemporary extension.
• New walls. Fitting the frame during first fix avoids the disruption of retrofitting later.

Decide early

The single most useful step is to decide on pocket doors before the wall drawings are finished. That way:

• the architect or designer can draw the wall at the right thickness
• the builder can order the kit with the rest of the first-fix materials
• the electrician knows to keep the pocket section clear
• the plumber knows not to route pipes through it

Write the pocket door into the drawings or specification, with the door size, kit and finished wall thickness. If it isn’t written down, it’s easy for a standard hinged lining to go in by default.

Choosing the wall build

Most internal walls in extensions are stud partitions, either timber or metal, which is exactly what pocket door kits are designed for. The kit frame replaces part of the studwork and is boarded over with the rest of the wall.

The kit must match the wall thickness. Rocket Door Frames, for example, publishes these builds for its standard kits with one layer of 12.5mm plasterboard each side:

Our pocket door wall thickness guide explains how these figures are worked out, including fire-rated builds with two layers of board.

If the pocket needs to sit in a masonry wall, such as the original back wall of the house, the job is more complex. Opening up a load-bearing wall needs structural design and building control sign-off, and the pocket itself is usually formed in a new stud section. See can you fit a pocket door in a brick or block wall? for the options.

Getting the size right

A single pocket door needs a clear length of wall beside the opening of roughly twice the door width, plus a little extra for the frame. Eclisse’s Classic single table, for example, gives an overall frame width of about 1888mm for a 926 x 2040mm door. A double pocket door needs twice that again.

In an extension, check that this length of wall isn’t also needed for:

• a window, rooflight upstand or external door
• kitchen units, an island or built-in storage
• radiators, sockets, switches or a thermostat
• a steel beam bearing or column

Taller doors are popular in extensions with higher ceilings. Standard metric doors are 2040mm high, and some kits are made for taller leaves to order. Our floor-to-ceiling doors guide and made-to-measure pocket doors cover what to check when the opening is non-standard. The pocket door sizes guide lists the standard UK sizes.

Building regulations and fire safety

Most extensions need building regulations approval, even when they don’t need planning permission. The two are separate. You can apply to your local council through the Planning Portal or use a registered building control approver.

Pocket doors don’t have their own special rules, but the doors in and around an extension can be affected by fire safety guidance in Approved Document B. A couple of points often come up:

• Escape routes. If the house has a storey more than 4.5m above ground level, Approved Document B expects a protected stairway or an alternative approach. Changing the layout of the ground floor as part of an extension can affect this, and some doors may need to be fire doors.
• Inner rooms. An inner room is one you can only reach through another room. Approved Document B only accepts certain inner rooms, such as kitchens, utility rooms, bathrooms and WCs, or rooms with a suitable emergency escape window.

If a doorway needs to be a fire door, a standard pocket kit won’t do. You’d need a pocket system certified as an FD30 assembly, which usually means a thicker wall with two layers of fire-rated board. Our guide to FD30 pocket doors explains this. Agree which doors need fire protection with your designer and building control before you order.

Services in the wall

The pocket section must be completely clear. That means:

• no sockets or switches on either face of the pocket
• no cables, pipes or ducts running through it
• no underfloor heating manifold or controls in that wall

Move switches to the other side of the opening, or onto the side of the wall without a pocket. Tell the electrician and plumber at the start, because the extension’s first-fix services often go in quickly.

Floors, skirting and finishes

Extensions often get a new floor finish, sometimes over underfloor heating. Think about:

• Finished floor level. Order the door to suit the final floor height, not the screed level, so the gap under the door is right.
• Floor guide. Most kits use a small floor guide at the mouth of the pocket. Check how it fixes into your floor finish.
• Skirting. Skirting on the pocket faces must be fixed with adhesive or short fixings that can’t reach the door. Long nails or screws can scratch the door or jam it.

For a minimalist look, a frameless pocket kit can be plastered flush with no architrave. If you go for that look, plan the plaster finish and decoration with the plasterer before the boards go up.

Handles and hardware

Pocket doors use flush pulls, edge pulls and, for WCs and utility rooms, privacy locks. In an open-plan extension, a soft-close damper is a nice upgrade that stops a heavy door slamming. Browse pocket door hardware, and see our guides to pocket door handles and soft close pocket doors.

A simple planning checklist

1. Mark each pocket door on the drawings with door size and finished wall thickness.
2. Confirm the wall build (stud size and boarding) matches the kit.
3. Check the clear wall length beside each opening.
4. Agree with building control which doors, if any, need to be fire doors.
5. Brief the electrician and plumber to keep the pockets clear.
6. Order the kit in time for first fix.
7. Set the door height to the finished floor level.
8. Fit the door leaf and hardware after decorating, following the kit instructions.

When you’re ready, browse our pocket door kits and the pocket door installation guide.

FAQs

When should a pocket door frame go in during an extension build?

At first fix, when the stud walls are being framed and before boarding. The frame becomes part of the wall, so it has to be in place before the plasterboard goes on.

Do I need building regulations approval for a pocket door?

A pocket door on its own isn’t usually the trigger, but most extensions need building regulations approval anyway. Building control may also need to agree which doors are fire doors.

Can a pocket door go in an external wall?

Standard internal pocket door kits are designed for internal partitions, not external walls. For the outside of an extension, look at external doors designed for that purpose.

Can I have a pocket door in a wall with underfloor heating?

Yes. Underfloor heating is in the floor, not the wall, but check how the floor guide fixes so it doesn’t damage the heating pipes, and keep any controls off the pocket faces.

What wall thickness should I ask my builder for?

It depends on the kit. Common finished thicknesses are 100mm, 115mm and 125mm for standard kits. Fire-rated kits need thicker walls. Agree the kit first, then build the wall to suit.

Planning an extension?

Send us your drawings or opening sizes and we’ll help you match the right kit to your wall. Get in touch with our team before your builder reaches first fix.