The short answer
A pitched roof is a roof built with sloping surfaces, usually two or more, that shed rain and snow by gravity. It is the standard roof on British houses, covered in tiles or slates over a timber frame. The angle of the slope is called the pitch. Anything above a shallow angle counts as pitched, and roofs below about ten degrees are normally treated as flat. A pitched roof drains quickly, and it creates a loft space below.
What counts as pitched
The line between pitched and flat is a matter of angle. A flat roof is built with just enough fall to carry water to an outlet, usually a degree or two. A pitched roof has a clear slope, from a shallow roof of around fifteen degrees to a steep one of fifty or more. In the UK, most houses have a slope somewhere between thirty and forty-five degrees.
The distinction matters because the covering depends on it. Tiles and slates work by overlapping, so water runs over each one and down to the next, and they only work above a minimum angle. Flat roofs use continuous membranes instead. Our page on roof pitch and how it is measured goes into the angles.
The parts of a pitched roof
The frame is made of timber. Rafters run from the wall plate at the eaves up to the ridge board or ridge beam at the top. In many modern houses, factory-made trusses do the same job. Purlins, which are horizontal beams, support rafters at mid-span on larger roofs, and ceiling joists tie the walls together at the bottom. Our guide on roof timbers explained names each one.
On top of the frame comes the underlay, then battens, then the tiles or slates. The ridge caps the top, hips cap sloping corners, and the verge finishes the edge at the gable. Valleys, flashings and gutters complete the system. Every part has a job, and a fault in one can affect another.
Common shapes
The simplest is the mono-pitch, a single slope used on lean-to extensions. The gable roof has two slopes meeting at a ridge. The hipped roof slopes on all four sides. The mansard has a steep lower slope and a shallow upper one. Dormers and valleys add complexity where roofs meet. Read about the two most common shapes in our answers on gable roofs and hipped roofs.
Coverings
Clay and concrete tiles are the most common coverings, followed by natural and artificial slate. Each has a minimum pitch, a weight, a fixing method and a lifespan. Clay tiles hold their colour for a long time, concrete is cheaper and heavier, and slate is thin and elegant but needs skilled laying. For more on the choice, read about concrete versus clay roof tiles.
Warm and cold pitched roofs
Pitched roofs are also described by where the insulation sits. In a cold roof, the insulation lies on the loft floor between the ceiling joists, and the space above stays cold and is ventilated so damp air can escape. This is the traditional arrangement and the one most British houses have. In a warm roof, the insulation follows the rafters, so the loft is inside the heated envelope and is often used as a room.
The difference matters when work is planned. A cold roof needs clear air paths at the eaves and ridge, while a warm roof needs a design that stops condensation inside the structure. Changing from one to the other is a bigger job than it sounds, and it affects the underlay, the vents and the building control notice.
How a pitched roof sheds water
Water runs down the covering in a thin sheet and is carried at the bottom into the gutter. Tiles and slates lap over each other, so water has to travel upward against gravity to get through, which it cannot do except in wind-driven rain or on a very shallow slope. The underlay beneath is a back-up. If a tile is lost, the underlay holds the rain for a time, and that gives you breathing space to arrange a repair.
Why people choose them
A pitched roof sheds water and snow quickly, so leaks from standing water are rare. The covering is made of many small units, so a damaged one can be replaced without disturbing the rest. The loft gives storage or room for conversion, and the roof can last many decades with maintenance. The drawbacks, which include cost, height and exposure to wind, are set out in our answer on the disadvantages of a pitched roof.
Looking after one
Keep the gutters clear, look at the roof from the ground after storms, and have a survey if you see slipped tiles, daylight in the loft or stains on the ceilings. We photograph the roof, the loft and the junctions and tell you plainly what needs doing. See the pitched roofing page for our work on pitched roofs.
Every roof is different. A free survey with photos settles it for yours.
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