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Why replace your roof
- Warmer in winter
- Cooler in summer
- Quiet when it rains
- A room you use all year
Our prices and data come from Met OfficeHM Land RegistryLABCPlanning PortalWhich?
P-shaped conservatory roof replacement
A P-shape joins a lean-to to a Victorian bay, giving a long room with a rounded end. Its roof has a single slope, a faceted bay and a valley where the two meet, which makes it one of the more involved roofs to replace and a common place for an old roof to leak.
Every roof option for a P-shape conservatory
Medium size, fitted.
| Roof | Price | Fitting | Best for |
|---|---|---|---|
| Tiled roof | £10,900 to £15,400 | 3 to 6 days | Using the room every month of the year |
| Glass roof | £5,100 to £8,200 | 2 to 4 days | Keeping the light and the view of the sky |
| New polycarbonate roof | £3,900 to £6,100 | 1 to 2 days | The lowest cost fix for a leaking roof |
| Hybrid roof | £9,600 to £14,800 | 4 to 7 days | Warmth with pools of daylight |
| Insulated roof panels | £2,600 to £5,400 | 1 to 3 days | A warmer room on a tighter budget |
| Orangery conversion | £14,000 to £35,000 | 7 to 15 days | A full extension feel without building a new room |
What is different about a P-shape roof
- The valley where the two sections meet is a common leak point on old roofs and needs careful detailing on the new one.
- Two zones in one room, often a dining area and a lounge, so lighting and heating are planned for both.
- More roof area and more junctions mean higher prices than a single shape of the same floor area.
Tiled roof
Tiled P-shape roofs need a ring beam round both sections and a well detailed valley. Ask how the valley is lined and guaranteed.
Glass roof
Glass on a P-shape mixes rectangular and tapered units. The bay end tends to be the hottest part of the room.
New polycarbonate roof
Replacing polycarbonate on a P-shape is still quick, but the valley seals are worth replacing at the same time.
Hybrid roof
Many P-shape owners tile the lean-to section and put glazed panels in the bay, which gives a bright end to a warm room.
Insulated roof panels
Panel systems can follow both shapes, though the bay facets need more cutting.
Orangery conversion
P-shape to orangery conversions are larger projects and often come with new walls.
Why the valley matters most
A P-shape is two roofs in one: a single-slope lean-to along the house and a faceted Victorian bay at the end. Where they meet there is a valley, a channel that collects rainwater from both roofs. On old conservatory roofs the valley is one of the most common leak points, so it deserves the most attention on the new one.
Whatever roof you choose, ask how the valley will be lined, what it is made of, and whether the guarantee covers leaks at the valley specifically. If you are only re-sheeting a polycarbonate P-shape, it is worth replacing the valley seals at the same time, since the rest of the job is quick.
Box gutters and the house wall
If your roof has a box gutter, a deep gutter set into the roof rather than hung at the edge, it carries real weight under a solid roof, so the fixings matter. The makers’ guides are specific:
- Guardian fixes box gutters at about 450mm centres, drilling into brick rather than mortar.
- LEKA fixes them every 400mm with gallows brackets every 1200mm, and calls for steel uprights and a structural engineer’s input if the gutter projects too far for a bracket.
- Guardian notes that its box gutter insulation sits 82mm below the aluminium, so there must be room for opening windows and doors underneath.
Ultraframe says its LivinRoof box gutter can span up to 6m. Leaks at box gutters and flashing appearing years after installation are the main theme of negative reviews of Ultraframe roofs, so ask how the gutter is sealed and how it drains.
Two pitches, one roof
The lean-to section of a P-shape is often shallower than the bay. The tile or glass you choose has to suit the lowest pitch on the roof, not just the steeper bay, so check each system’s minimum. Tiling round the bay also means tapered cuts on every facet and capping on every hip, which is part of why ExpertSure reports Equinox taking 5 to 7 days on a P-shape against 3 to 5 on a standard Edwardian. Guardian says its roof can be made for P-shaped layouts.
Two zones: planning light and heat
A P-shape usually works as two areas, often a dining space along the house and a lounge in the bay. A popular hybrid roof layout tiles the lean-to section and puts glazed panels in the bay, which gives a bright end to a warm room. Plan spotlights for both zones before the plasterboard goes up, and make sure any new lighting circuits come with an electrical certificate.
Size and structural checks
More roof area and more junctions mean higher prices than a single shape of the same floor area. Size also affects the paperwork. Equinox roofs over 18m² need structural calculations, and LABC says you may be asked for calculations showing the structure can withstand snow loading. The building regulations exemption for conservatories only covers a floor area of up to 30m², so measure yours: a larger one is not an exempt conservatory, so ask building control before any roof replacement, even glass for glass.
Questions to ask about your P-shaped roof
When you get quotes, ask each installer:
- How will the valley be lined, and does the guarantee cover leaks there?
- Is there a box gutter, how is it supported, and is there clearance for my windows and doors?
- Does the tile or glass suit the pitch of the lean-to section, not just the bay?
- Are structural calculations needed, and are they in the price?
- How many days on site?
If your roof is already leaking at the valley, our guide to a leaking conservatory roof explains when repair is enough.
Comfort through the year
Questions
Can a P-shaped conservatory have a solid roof?
Generally yes. Guardian says its roof can be made for P-shaped layouts, and other systems cover the lean-to and Victorian shapes that make up a P. As with any solid roof, the frames and base have to pass the survey and building control checks first.
Why do P-shaped conservatory roofs leak at the valley?
How long does it take to replace a P-shaped conservatory roof?
Longer than a simple shape. ExpertSure reports that Eurocell's Equinox tiled roof takes 5 to 7 days on a Victorian or P-shaped conservatory, against 3 to 5 days on a standard Edwardian, with the roof weathertight by the end of day two.
What is the best roof for a P-shape conservatory?
For a room you can use all year, a lightweight tiled roof is usually the best fit: typically £10,900 to £15,400 on a medium P-shape. If daylight matters most, solar control glass costs £5,100 to £8,200. On a tight budget, insulated panels from about £2,600 make a real difference.
How much does it cost to replace a P-shape conservatory roof?
For a medium P-shape conservatory, expect £2,600 for the simplest option up to £15,400 for a premium tiled roof. The table on this page shows every option.
Make your P-shape conservatory a room you use all year
Compare up to four quotes from local installers who fit this shape of roof.