Guidelines for roof sections falling below a 35° Pitch
On some developments design limitations can arise on comparatively small areas of the roof which restrict the available roof pitch to below 35° which is the minimum pitch recommended for all plain tiles in BS EN 5534. In these situations, it is necessary to use a secondary roof system laid below the tiles to provide assured weather protection and enhanced ventilation.
Below are some alternatives supplied directly by the respective manufacturers and the information is provided only as a reference, please be aware that Dreadnought Tiles do not supply or provide any warranty on the information or products described.
Only except in very exceptional circumstances should pitches of less than 30° be used with plain clay tiles, please refer to our sales team to discuss any specific queries you may have.
The Ondutile system manufactured by Onduline Building Products Ltd allows plain double lap tiles to be laid to roof pitches as low as 22.5°, and is covered by British Board of Agrement certification, details are available from the Onduline website https://onduline.co.uk/products/ondutile/
Tyvek® Supro - installed in two layers with staggered laps can be useful for roofs with height restrictions such as with single storey lean-to extensions. It is quite common for these roofs to present a relatively small area and to discharge only a limited amount of rainfall. Whilst this method is very effective it’s use is limited in main roofs, especially ones of two storey height.
Using this double felted system allows the use of Dreadnought tiles on roofs as low as a 30 degree pitch.
For advice on the use of Tyvek® membranes please contact BKC Technical: 0117 970 9454/55
Video installation link: https://www.dupont.co.uk/resource-center.html?BU=pbs&restype=video