A pitched roof is a roof that slopes downwards, typically in two parts at an angle from a central ridge, but sometimes in one part, from one edge to another. The ‘pitch’ of a roof is its vertical rise divided by its horizontal span and is a measure of its steepness.
A pitched roof is in contrast to a flat roof which, technically, is any roof with a slope less than 10°; however, in practise they tend to be much shallower, commonly being expressed as a gradient and can be anywhere from 1:40 to 1:80. For more information, see Flat roof.
The two basic construction methods of pitched roofs are:
- Cut roof: A traditional method of cutting timber on-site and building up the roof using rafters, joists, purlins, ridge boards, etc.
- Truss roof: Prefabricated trusses which are delivered to site and erected.
 Types of pitched roof
There are several different types of pitched roof:
A mono pitch roof is one which slopes from one side of a building (or part of it) to another. The mono pitch roof was commonly used to form extensions in Victorian times and is still used in a similar fashion today. In domestic construction, it typically comprises a series of rafters fixed to walls at either end of the roof span which support battens to which the roof covering is fixed.
By adding ceiling joists, a length of timber running horizontally between the rafter feet, to the couple roof form, the structure becomes much more secure. The joist acts as a tie preventing the outward deflection of the wall and increases the potential roof-span. they can also be used to support a flat ceiling.
By raising the height of the ceiling joists higher than the bottom of the rafters, the collar roofa llows upper rooms to be constructed partly in the roof space, leading to some economies by slightly reducing the height of the external walls and therefore the amount of brickwork needed.
In order to increase potential roof spans without compromising wall stability, increasing rafter sizes or attracting extra costs, purlins can be introduced. By installing a purlin into the roof structure, rafters are given extra support and no longer needed to be as thick and heavy.
In modern house construction the most common form of trussed rafter is known as the fink or 'w' truss. This consists of a rafter incorporating tension and compression members in the shape of a W. This trussed rafter is capable of spans up to 12 m and can be designed to accommodate many different pitch angles.
The most common types of covering for pitched roofs are:
 Related articles on Designing Buildings Wiki
Councils are reported to be considering taking up rarely-used executive powers to keep the planning and development system moving during the coronavirus pandemic.
Historic England's 'After a Flood' provides timely advice on how to dry walls properly and avoid further damage to the building fabric.
Context Issue 162 offers a peek into an archive of timber conservation history through the records of the practice of FWB and Mary Charles Chartered Architects.
To meet the government’s target of being carbon neutral by 2050, we must recycle, reuse and responsibly adapt our existing historic buildings, according to this year’s Heritage Counts report, so Historic England and partners are calling for a reduction in VAT rates to incentivise this more sustainable option.
Donald Insall Associates, with the help of Historic England, has completed restoration work of Moseley Road Baths, being converted for use as an arts and culture venue.
Celebrate your local ‘retired members’ and ‘successful learners’ with £500 cash prizes and 2020 Brighton School places!
The Conservation Hierarchy is a new framework developed by the University of Oxford to help construction projects achieve Biodiversity Net Gain.
Jacqueline Hughes, senior risk analyst at Equib, in pbctoday discusses how project managers for town centre developments can get their risk management strategies right.
A new paper from the Adam Smith Institute argues that the problem with the High Street has been totally misunderstood, saying that we need to reform restrictive planning rules and reject a policy of managed decline to reinvigorate our town centres.
The Whole Life Cost of Energy (WLCoE) calculator – issued by government in BETA form – is intended to help building owners and operators to understand the full financial cost of the energy their buildings use, and welcomes feedback
New research published by Historic England (HE) shows the value of heritage to England’s economy as it contributes to economic prosperity and growth through jobs in the heritage and construction sectors and from tourism.
Investigations have begun into what caused part of Chester’s Roman city wall to collapse during construction work.