7.2 Pitched roofs
This chapter gives guidance on meeting the Technical Requirements for pitched roofs, including:
- coverings
- vertical tiling
- fixings
- ventilation
- weatherproofing.
Definitions for this chapter#
For the purposes of this chapter, the following definitions apply:
| Air impermeable weatherproof covering | A roof covering where the airflow through it is not greater than 17.4 Ar (in m3/h) |
| Air permeable weatherproof covering | A roof covering where the airflow through it is greater than 17.4 Ar (in m3/h) |
| Air and vapour control layer | A continuous layer to restrict the movement of air and water vapour |
| Cavity barrier | Cavity barriers are a construction within a cavity, other than a smoke curtain, to either close a cavity to stop smoke or flame entering, or restrict the movement of smoke or flame within a cavity |
| Coastal locations | A site within a distance of 500m from the general coastline of the United Kingdom |
| Cold pitched roof | A roof where the insulation is laid horizontally at ceiling level and the space above is unconditioned |
| Complex roof | Large span roofs of over 12m, or roofs with complex geometry and/or features |
| Conditioned space | Occupied space in which the temperature and humidity are controlled |
| Fire-stopping | Fire-stopping is a seal provided to close an imperfection of fit or design tolerance between elements or components, to restrict the spread of fire and smoke |
| Hybrid roof | A roof where the insulation is positioned partly on a horizontal ceiling, vertical members and partly at the rafter line |
| Normal ceiling | A ceiling with a typical air permeability of 300 mm2/m2 (0.3%) |
| Perimeter roofing element | The single roofing element (eg tile, slate, shingle) at any discontinuity in the plane of the roof, including, roof windows, dormers, valleys, roof edges etc |
| Pitched roof | Part of the external envelope of a building that is at an angle between 10° and 70° |
| Sarking board | Softwood timber boards, fixed over the rafters of a pitched roof, used for the purposes of roof bracing. Boards may be tongue and grooved or open jointed |
| Sarking sheet | Tightly jointed sheet boards, fixed over the rafters of a pitched roof, used for the purposes of roof bracing (eg OSB, exterior grade plywood, etc) |
| Solar roof panel | Solar roof panels could be either solar photovoltaic or thermal roof panels, and either be ‘on-roof’ type or integrated into the roof covering |
| Type HR underlay | A membrane with a high water vapour resistance, sd, greater than 0.05 m (0.25 MN∙s/g) |
| Type LR underlay | A membrane with a low water vapour resistance, sd, not exceeding 0.05 m (0.25 MN∙s/g) |
| Unconditioned space | Unoccupied space in which the temperature and humidity are not controlled |
| Warm pitched roof | A roof where the insulation follows the rafter line |
| Well-sealed ceiling | A ceiling with a typical air permeability of not more than 30 mm2/m2 (≤0.03%) |
Clauses for 7.2 Pitched roofs
- 7.2.1 Compliance
- 7.2.2 Provision of information
- 7.2.3 Design of pitched roofs
- 7.2.4 Protection of trusses
- 7.2.5 Durability
- 7.2.6 Wall plates
- 7.2.7 Joints and connections
- 7.2.8 Restraint
- 7.2.9 Bracing for trussed rafter roofs
- 7.2.10 Strutting for site formed attic trusses and cut roofs that form a floor
- 7.2.11 Support for equipment
- 7.2.12 Access
- 7.2.13 Dormer construction
- 7.2.14 Underlay, sarking boards and sheets
- 7.2.15 Ventilation, vapour control and insulation
- 7.2.16 Fire-stopping and cavity barriers
- 7.2.17 Battens
- 7.2.18 Roof coverings
- 7.2.19 Fixing tiles and slates
- 7.2.20 Weathering details
- 7.2.21 Valleys and hidden gutters
- 7.2.22 Drainage
- 7.2.23 Fascias and trim
- 7.2.24 Spandrel panels in cold roofs
- 7.2.25 Roof cassette systems
- 7.2.26 Solar roof panels
- Figure reference table
Last updated: 2nd January 2024