What British standards impact tiled roof specification

The most important British Standards for tiled roofs are BS 5534, BS 8000-6 and BS 5250. BS 5534 and BS 8000-6 broadly relate to design, specification and installation, while BS 5250 focuses on moisture management in buildings including condensation control.

BS 5534 - design and installation of slated and tiled roofs

BS 5534:2014+A2:2018 is the code of practice for slating and tiling, including shingles, for pitched roofs and vertical cladding.

Whilst there has been no further updates to BS 5534 since 2018, to recap all single lap tiles must be mechanically fixed using the appropriate combination of clips and/or nails, in accordance with BS 5534 wind load calculations. Mortar cannot be relied upon as the primary means of securing roof tiles and mechanical fixings must always be used.

Roofing battens must meet BS 5534 requirements. Battens must be appropriately marked and be accompanied by documentation including the name of supplier, origin (i.e. species code), grading, size, type of preservative and method of treatment used. 

Underlays must meet the requirements of BS 5534, to ensure they are securely installed to resist the calculated wind loads.

BS 8000-6: 2023 - installation of slate and tiled roofs

BS 8000 is the code of practice for workmanship on building sites and Part 6 specifically applies to slating and tiling of roofs and walls. This standard focuses on installation and should be read in conjunction with BS 5534. 

BS 5250 - Ventilation and moisture control

BS 5250:2021 is the code of practice for the management of moisture in buildings.

The standard provides a whole building approach to moisture safe design and gives recommendations for its control. The causes and effects of surface and interstitial condensation in buildings are covered, with a specific section for the control of condensation in roofs.

More detailed information on all of the requirements is given in our Roofing specification guide.

Key design considerations for moisture control:

• Considering moisture generated by the construction process, building occupants and weather
• Providing well-sealed ceilings to minimise the transfer of moist air into roof spaces
• Avoiding construction gaps
• Avoiding roof access doors or hatches in rooms that produce excessive moisture
• Use of sealed loft hatch and frame to be tested for air leakage (BS EN 13141-1)
• Sealing of all services and rooflights
• Use of recessed light fittings rated IP60 to IP65 to BS EN 60529
• Sealing of the head of cavity walls to prevent transferring warm moist air into the loft

Key design considerations for thermal insulation:

Suitable insulation should be provided to prevent heat loss and cold bridges in roof construction.

Measures to prevent moisture ingress, condensation and air leakage should be incorporated into the construction, with particular attention being given to the thermal continuity of insulation at junctions between walls, floors and roofs.

As insulation levels increase so does the potential risk of condensation. Designers should consider BS 5250 guidelines to provide suitable ventilation provisions as part of the moisture management strategy in both new build and re-roofing projects.

BS EN 13859-1 breathable roofing underlay

Products such as breathable underlays should comply with BS EN 13859-1, the standard for flexible sheets for waterproofing and underlays for discontinuous roofing. They may also require Third Party accreditation, such as a BBA certificate.

You can find out more about roofing specification in our guide.