The verge on a roof is probably the most vulnerable part due to its exposure to wind and water penetration. Traditionally the most common practice way of protecting this is by filling the gap between the wall and roof with wet mortar. This however, is now a rare occurrence as mortar as we know expands, shrinks, cracks and falls out after a number of years thus leaving the verge once again exposed to the elements. Mortar also acts like a big sponge soaking water into the roof space. Having an exposed verge leads to water entering and rotting the ends of the battens and weakening the integrity of the roof.
Even when using mortar as a solution it doesn’t do one very important aspect and that is securing the slates in place and protecting them for being blown off in high winds. All it takes is just one slate coming loose then a domino effect takes place with multiple slates braking loose.
In Ireland, 90% of roofs are secured in place using a Dry Verge System, in Scotland its 80%, yet in England and Wales this figure falls dramtically to around 20%.
With changes to regulations BS5534 code of practice for slating and tiling slate and tile verges, roofers must adapt and change to using a Dry Verges System rather than the using traditional methods.