A pitched roof is any roof steep enough to shed water by gravity rather than by a designed fall, and in Britain that means almost every house roof. The confusion is in the naming. A dual pitched roof, a double pitch roof and a 2 pitch roof are all the ordinary gable roof with two slopes meeting at a ridge, and knowing that saves you comparing quotes for what you thought were different things.
The shapes, and their real names
A gable roof has two slopes meeting at a ridge with a vertical wall at each end, and that is what a dual pitched roof, a double pitch roof and a 2 pitch roof all describe. A hipped roof slopes on all four sides, which removes the gable walls and adds two more lines of detail for a roofer to form. A mono pitch or lean-to has one slope, usually against a wall. A mansard has two pitches on the same slope, the lower one much steeper, and is normally there because somebody wanted a room in the roof.
What is underneath any of them
Below the covering, a traditional cut roof has rafters, purlins and a ridge board assembled on site, while most houses built since the 1970s have prefabricated trusses. Over that goes a breathable underlay, then treated battens at a gauge the covering dictates, then the tiles or slates themselves, mechanically fixed to a pattern set by how exposed the site is. The pitch decides what coverings are allowed: a slate that is fine at forty degrees will drive rain under itself at twenty.
Why the shape changes the price
Roofers price detail, not area. A plain gable roof is the cheapest shape per square metre because it has two slopes, one ridge and two verges. A hipped roof of the same footprint adds four hip lines, each of which has to be cut and bedded or fitted with a dry system. Valleys, dormers and chimneys each add a junction that leaks if it is formed badly, and each is priced by the metre or by the item rather than being absorbed into the rate.
Questions people ask about pitched roof
What pitch does a roof need to be?
It depends entirely on the covering, because each product has a minimum pitch below which wind can drive water back under the laps. That minimum is set by the manufacturer and is the reason you cannot simply swap a tile for a slate on the same roof without checking.
Can a flat roof be turned into a pitched roof?
On a garage or a single-storey extension it is a common way to end a repeated leak, and the pitch removes the standing water that caused it. It is a structural alteration, so it is controlled work and may need planning permission depending on height and position.
Is a hipped roof more expensive than a gable?
For the same footprint, usually yes, because the hips are extra lines of detail and the covering has more cuts and more waste. The difference is in labour and detail rather than in the price of the tiles.