Verges

Is there a dry verge system for Stonewold I?

Ambi-Dry Verge units can be used with Stonewold I slates. Additional battens are fixed to a minimum of two supports 2 mm below the tiling battens to which the Ambi-Dry Verge Units are fixed. This is an ideal solution in situations where the original mortar bedded verge has failed and a new dry verge is required.

 

What is the correct width for mortar at verges?

BS 8000: Part 6: 2013: Code of practice for slating and tiling of roofs and walls, Workmanship on building sites, states 'A 100mm wide bed of fully compressed mortar width should be laid onto the undercloak. Tiles should be bedded solidly and edges finished neatly’. The width of the undercloak is normally 150mm of which 50mm laps under the batten ends. Once the tiles are bedded into the mortar it will spread by a further 25mm therefore a 75mm width of mortar should be applied which will spread to 100mm when bedded/compressed.

 

What should the tile overhang be for a verge with a gable ladder?

BS 5534: 2014, Code of practice for slating and tiling for pitched roofs and vertical cladding, states that a verge overhang, when unsupported, can be between 38 and 50mm for double-lapped plain tiles, fibre-cement slates and natural slates and between 30 and 60mm for single-lapped interlocking tiles. On a verge formed with a gable ladder, 35mm wide rafters, 19mm bargeboard and 38mm overhang, the distance from the verge edge to the ends of the tiling battens should be 100mm such that the 100mm wide compressed mortar bed just touches the batten ends, which is acceptable with treated battens.


If the overhang is increased to 50mm, the distance from the verge edge to the ends of the battens becomes 112mm giving a gap of 12mm between the compressed mortar bed and ends of the battens which avoids contact between mortar and batten. It is for this reason that it is better that the overhang is 50mm on gable ladder verges.