An L-shaped conservatory wraps around a corner of your house, running along the back wall and turning along the side, so it can be reached from two or more rooms and opens onto the garden on several sides. It is the shape to consider when your house sits on a corner plot, when the best part of the garden lies to the side, or when you want a kitchen and a living room both to open into the same glazed space. Because it is effectively a side extension and a rear extension joined together, an L-shape has its own structural and planning points that single-style rooms do not. This page explains them. For a summary of all styles, see our conservatories page.
Where an L-shaped conservatory makes sense
- Detached houses with garden on two sides, where a rear-only room would leave the side garden unused.
- Homes with a kitchen at the back and a lounge at the side, so both rooms gain a link to the garden through one conservatory.
- Houses with an existing single-storey extension, where the conservatory can wrap the corner and tidy up the rear elevation.
- Plots where the sun moves round the house, giving morning light in one leg and evening light in the other.
It is less suitable where the side passage is narrow, or where that side faces a road, for reasons covered below.
The corner: posts, valleys and structure
Where the two legs meet, the conservatory turns through 90 degrees. Outside, that corner needs a structural post to carry the roof, and inside, the roofs of the two legs meet in a valley that collects rainwater from both slopes. At the house end, there is an internal corner where the roof meets two walls, which needs careful flashing.
Making the corner post work for you
The outer corner post is the hardest element to design away, but you can make it less obtrusive. Aluminium frames carry loads in slimmer sections than UPVC, so a corner in Cortizo or Alunet aluminium can look lighter. Some owners ask for doors that meet at the corner without a post; whether that is possible depends on the roof load, the door system and the sizes involved, so ask us and we’ll confirm for your sizes. Where the post stays, we position furniture so it frames the view rather than blocking it.
Roof options for each leg
Each leg can have its own roof style. A common arrangement is a lean-to roof on both legs meeting at a hipped corner, which keeps the height low under first-floor windows. On taller houses, one leg can carry a pitched Edwardian roof for more headroom. A solid roof on one leg and glass on the other is also possible, though a solid roof normally means Building Regulations approval.
Planning rules for wrap-around conservatories
This is where an L-shape differs most from other styles. Government technical guidance says that where an extension fills the area between a side wall and a rear wall, the restrictions on extensions beyond both rear walls and side walls apply (government technical guidance). In practice, to stay within permitted development:
- the side leg can be no wider than half the width of the original house, and no more than 4 metres high (Planning Portal);
- the rear leg must meet the normal rear depth limits of 3 metres, or 4 metres on a detached house, unless prior approval is obtained;
- eaves within 2 metres of a boundary cannot exceed 3 metres;
- the side leg cannot be built in front of a side elevation that fronts a highway, which often affects corner plots (technical guidance PDF);
- on designated land, such as conservation areas, any side extension needs householder planning permission (Planning Portal).
Those limits apply to the total enlargement, including earlier extensions (Planning Portal). If your design goes beyond them, a planning application is the normal route, and we can prepare drawings that show exactly what is proposed. Always check with your local council before committing.
Multiple access points
An L-shape can connect to the house through two or more openings, and open to the garden through two or more sets of doors. That flexibility is its main attraction, but a few rules follow from it:
- To keep the conservatory exempt from Building Regulations, the Planning Portal says it must be separated from the house by external-quality walls, doors or windows, under 30 square metres and independently heated (Planning Portal). Every opening between house and conservatory counts.
- Any new structural opening in the house wall needs Building Regulations approval, even if the conservatory itself is exempt.
- Glazing in and beside doors within 1500 mm of the floor, and low-level glazing within 800 mm, must be safety glass (building control guidance).
For the garden doors, wide Smart Visofold or Cortizo bifolds work well on the longer leg, with Reynaers ConceptPatio 130 sliders or French doors on the shorter one. Spreading doors across both legs means the room never becomes a corridor to a single exit.
Drains and services at the side of the house
Side passages are often where the soil stack, gas meter, outside tap and manholes are. Before designing the side leg, we locate them. Thames Water requires a build over agreement for work within 3 metres of a public sewer (Thames Water), and moving a soil pipe or meter adds time and cost. If the side leg sits close to a neighbour’s boundary, the Party Wall etc. Act 1996 may also require you to give notice (gov.uk).
Cost factors for an L-shape
Published guides rarely price L-shaped conservatories; Checkatrade’s, for example, lists lean-to, Victorian and Edwardian rooms only (Checkatrade). Expect more than a single-style room of the same area, mainly because of:
- the corner post, valley and extra flashing;
- a longer base following two walls, with more groundwork;
- moving drains, meters or pipes on the side leg;
- multiple door sets and any new openings into the house;
- a planning application if the design goes beyond permitted development.
Looking after an L-shaped conservatory
Clear the valley gutter at the corner every autumn, because it takes water from two roof slopes. Check the flashing at the internal corner where the roof meets the house, and keep the side-leg gutters free of debris from nearby fences and hedges.
Book a survey for your wrap-around conservatory
We will measure both elevations, find the drains and services, check the planning position and draw the room with every door shown. We cover Windsor, Maidenhead, Berkshire, Buckinghamshire, Surrey, west Kent and north West Sussex. Call 01753 965 005 or get a free quote online. You may also like our guide to P-shaped conservatories.
Frequently asked questions
What is an L-shaped conservatory?
It is a conservatory that wraps around a corner of the house, running along the back and turning along the side. It can connect to two or more rooms and open onto the garden on several sides. It suits detached houses and corner plots where the garden lies on more than one side of the house.
Does a wrap-around conservatory need planning permission?
Not always, but the rules are tighter. Government guidance says both rear and side extension limits apply, so the side section can be no wider than half the original house and no more than 4 metres high. Side extensions on designated land, or in front of a side wall facing a road, need permission.
Can I avoid a corner post in an L-shaped conservatory?
The outer corner usually needs a post to carry the roof, but aluminium frames make it slimmer than UPVC. Doors that meet at the corner without a post may be possible depending on the roof load, door system and sizes, so we check that for your design. We also plan furniture so the post frames the view.
How many doors can an L-shaped conservatory have?
It can have several, usually one or two openings into the house and doors to the garden on each leg. To stay exempt from Building Regulations, every opening to the house needs external-quality doors or windows. Any new structural opening in the house wall needs approval, and glazing in and near doors must be safety glass.
Why does an L-shaped conservatory cost more than a lean-to?
It has a corner post, a roof valley and extra flashing, a longer base following two walls, and often more doors. The side leg may also mean moving drains, pipes or a meter. If the design exceeds permitted development, there is a planning application too. We quote each L-shape individually after a full survey.