Single Slope · Low Eaves · Made to Measure
Lean-To Conservatories with Aluminium Frames and Glass Roofs
A lean-to is the simplest conservatory there is: one slope, running down from the house wall to the garden. That simplicity is exactly why it works — fewer junctions to leak, a lower profile against the house, and more usable floor area for the money than any other shape.
What a lean-to conservatory is
A lean-to conservatory has a single-pitch roof fixed to the house wall at the high side and carried on posts or a frame at the low side. There is no ridge, no valley and no hip, so there are fewer places for water to find. The clean rectangular footprint also means almost all of the floor is usable, unlike a gable or P-shape where the corners get awkward.
It is sometimes called a sunroom, a garden room or a Mediterranean conservatory. The construction is the same; the name usually reflects how the room is furnished.
Best for narrow gardens, bungalows and terraced houses
The lean-to earns its place where height is constrained. Under a bungalow eaves line, beneath a first-floor window, or on a terraced house where the rear elevation gives you limited wall height, a gable roof simply will not fit — but a shallow single slope will. It is also the least visually dominant option, which matters in conservation areas and on properties where the rear elevation is overlooked.
On a narrow plot, the rectangular plan means you can run a long frontage with a modest projection and still get a genuinely usable room.
Roof pitch, projection and drainage
Projection runs from 1,500 mm to 7,000 mm on the single slope. Frontage is unlimited because the roof is assembled from modules of 1,200–1,750 mm. Pitch is set by the available wall height and the drainage design rather than by a fixed rule, and we work it out at survey.
Drainage is where cheap lean-tos fail, because a shallow pitch moves water slowly. Our roofs use structural glazing — the outer pane is bonded to the frame, so the surface is flush and there are no glazing bars for water to pond against. Rainwater is carried in concealed gutters inside the rails, with a separate condensation channel beneath them, and the system is tested to EN 12207 Class 4 for air tightness.
Fixed roof or opening roof
A lean-to takes an opening roof particularly well, because a single slope lets the panels stack in one direction without a ridge in the way. With a retractable glass roof, up to 75% of the slope opens and each module can be driven independently — so the room works as a sealed glass extension in winter and an open terrace in summer.
If you want the simpler and less expensive route, a fixed insulated glass roof gives you the same daylight and thermal performance without the mechanism.
Glazing and shading
Roof glazing is normally a 21 mm insulated unit — toughened outer pane, argon cavity, laminated inner pane — with a solar-control Low-E coating that cuts solar gain and filters around 60% of UV. Where you want shade instead of light, insulated aluminium composite panels in your chosen RAL colour can be built into the same roof.
A shallow lean-to on a south or west elevation takes a lot of afternoon sun. For those, external glass roof blinds above the glazing are the most effective control, because they stop the heat before it reaches the glass.
Structure, wind and snow
Aluminium profiles are sized by structural calculation for the wind and snow loads at your postcode, with steel carriers where the span requires them and stainless-steel fixings throughout. No additional steel is needed up to a 5,000 mm projection; beyond that we design carriers for your span. On a lean-to the wall fixing matters as much as the frame, so the survey includes checking what the house wall can actually carry.
Building regulations for a lean-to conservatory
A conservatory is normally exempt from most building regulations while it stays under a certain floor area, is separated from the house by external-quality doors, and has an independent heating control. Overhead and low-level glazing must meet safety glazing requirements in all cases. Planning permission is usually not required for a single-storey rear lean-to within permitted development limits — the thresholds are in our planning permission guide.
Sizes and cost
Cost follows projection, frontage, roof type and glass specification, plus any groundwork. A 3,000 mm fixed lean-to and a 6,000 mm opening one are different projects. Typical ranges are in our conservatory cost guide.
Every quote follows a free survey and a 3D design showing the exact module layout. Ask for a survey and we will size it for your wall.
FAQ
Frequently asked questions
What is a lean-to conservatory?
A conservatory with a single-pitch roof that slopes down from the house wall, with no ridge or valley. It is the simplest and most space-efficient conservatory shape.
Is a lean-to conservatory cheaper than a Victorian or gable one?
Usually, for the same floor area. There are fewer roof junctions, less frame and a simpler structure. The glass specification and whether the roof opens have more effect on the final figure than the shape does.
What roof pitch does a lean-to conservatory need?
It depends on the wall height available and the drainage design. Structural glazing and concealed gutters let us work at shallower pitches than a traditional glazing-bar roof, which is what makes low-eaves installations possible.
Can a lean-to conservatory have an opening roof?
Yes, and the single slope suits it well because the panels stack in one direction. Up to 75% of the roof can open.
Will a lean-to fit under my bungalow eaves?
Often, yes. The low profile is the main reason people choose a lean-to. We check the available height at survey.
Do I need planning permission for a lean-to conservatory?
Normally not for a single-storey rear addition within permitted development limits, but listed buildings, conservation areas and flats are treated differently.
Free, No-Obligation Quote
Get your free design and quote
Tell us about your project and we will send a free design and quote. Manufacture usually takes up to 6–8 weeks, and a standard house installation 1–3 days.
- Choose the roof and walls you are interested in.
- Add approximate sizes in millimetres.
- Leave your details — we prepare a design and quote.