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L-shaped and corner garden rooms

A clever way to use a corner and split one building into two spaces, as long as you plan around the boundary rules.

Updated 22 October 2026

A small modern garden room with glass doors at the end of a fenced garden

The short answer: an L-shaped or corner garden room makes use of a corner of the garden and splits naturally into two zones, such as an office and a gym or store. The same rules apply as for any garden room, with one catch: if any part of the building is within 2m of a boundary, the whole building must be no more than 2.5m tall.¹ A corner room sits near two boundaries, so that limit usually applies.

Why people choose them

Awkward plots: a corner, a sloping site or an angled garden where a rectangle wastes space.
Two uses in one building: an office in one leg and a gym, store or seating area in the other.
A covered outdoor space: a common design encloses one leg and leaves the other as a covered seating area. An open, roofed seating area along the building may count as a veranda, which isn't permitted development, so check with your council or get a lawful development certificate first.¹

Some companies offer corner styles as standard. Rubicon, for example, lists a Corner style, and Eden builds L-shaped rooms to order.

The height rule matters most

In England, the government's guidance is clear: if any part of an outbuilding is within 2m of the boundary, the height limit for the whole building is 2.5m.¹ So if either leg of an L-shaped room comes within 2m of either fence, the far end of the other leg is capped at 2.5m too, even if it's well away from the boundary.

Height is measured from the highest ground next to the building, and decking doesn't count as ground.¹ On a sloping corner plot, that can catch you out.

In Wales, the Court of Appeal has ruled that for a room built right up against a boundary wall, the neighbour's ground can count as the ground next to the building.² If you're building tight to a wall in Wales, check with your council.

The other rules

Half the garden. All outbuildings and extensions together must cover no more than half the land around the house.¹
No raised platforms. Verandas, balconies and raised platforms over 30cm aren't allowed under permitted development.³ This matters if the covered leg has a raised deck.
Building regulations. In England and Wales, between 15 and 30m² inside, a single-storey garden room is exempt only if it's at least 1m from every boundary or built substantially from non-combustible materials. The 1m is measured to the nearest part of the building, including gutters and fascias.⁴ A corner room tucked tight into two fences will often need building regulations approval if it's over 15m², and every room over 30m² needs it.

In England, a garden room usually doesn't need planning permission if it's single storey, behind the front of the house, has eaves no higher than 2.5m and an overall height of no more than 4m with a dual-pitched roof or 3m with any other roof, and, together with other buildings, covers no more than half the garden. If any part is within 2m of a boundary, the whole building must be no more than 2.5m tall.³⁵ These rights apply to houses, not flats or maisonettes. Rules differ in Scotland, Wales and Northern Ireland. Our planning guide covers the details.

What they cost

We haven't found a reliable figure for how much more an L-shape costs than a rectangle of the same size. The major price guides don't treat shape as a cost factor. Bespoke rooms generally cost more than modular ones⁶, and many L-shapes are bespoke. Some companies make an L by joining standard modular units, which can keep the cost down.

As a guide, a mid-range 12m² garden room costs £18,000 to £24,000 and a 20m² room £40,000 to £50,000.⁶ Get quotes for both an L-shape and a rectangle to see the difference for your design.

Design points to discuss

The inside corner. Ask how the roofs meet and how rainwater drains from the inside corner, because that's where problems tend to start.
Doors and light. A glazed corner or doors on both legs make the most of the view, but more glass means more heat loss.
Separating uses. A partition or internal door between an office and a gym helps with noise and heating.
Access. Corner sites are often the hardest to reach, so check the route in for materials.

Questions people ask

Do L-shaped garden rooms need planning permission?

Not usually, in England, if they meet the outbuilding rules. But if any part is within 2m of a boundary, the whole building must be no more than 2.5m tall.¹

Are L-shaped garden rooms more expensive?

We haven't found a reliable figure. Bespoke rooms generally cost more than modular ones⁶, so get quotes for an L-shape and a rectangle of the same area.

Can a corner garden room go right up to the fence?

Yes, under permitted development in England, if it's no more than 2.5m tall and meets the other rules. Between 15 and 30m² inside, it needs building regulations approval unless it's built substantially from non-combustible materials, and over 30m² it needs approval anyway. Gutters and roof edges mustn't overhang your neighbour's land.⁴

Related guides

A garden path leading to a small building at the bottom of the garden

Planning permissionEvery outbuilding rule explained.

A dark garden shed with double doors among autumn leaves

Garden room with shedCombining a room and storage.

A bright, empty room with a sliding door onto a garden

Garden room sizesHow much space each use needs.

Sources

Ministry of Housing, Communities and Local Government, Permitted development rights for householders: technical guidance.
Court of Appeal, McGaw v Welsh Ministers [2021] EWCA Civ 976.
Planning Portal (England), Outbuildings: mini guide. Permitted development limits for outbuildings.
LABC, Does my new outbuilding need building regulations approval?.
legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E.
MyBuilder, updated 21 Oct 2026, Garden room cost guide.