A verge refers to the junction between the roof and the gable end of the building. A gable refers to the wall that infills between two opposite roof slopes and usually finishes in a triangular shape. The traditional way of finishing the roof at a gable wall is to use mortar. Traditionally this detail includes a layer of plain tiles, slates or fibre cement board to assist in the weatherproofing. Unfortunately all too often this type of verge is poorly installed, leading to eventual water ingress. 
 
Even if properly installed a verge detail will require regular maintenance as it is prone to mortar failure. Dry verge systems help avoid these defects and the need for periodic maintenance of the mortar bedding. For many tiles, special 'cloaked verge' tiles are available which neatly close the gap at the verge

 

 Dry Ridge systems come in a variety of designs but offer a similar level of performance. They are designed to secure the ridge tiles which are located at the apex of a roof. When using dry ridge systems the mortar joints between ridge tiles are replaced by plastic inserts, known as unions, that create the visual appearance of a mortar joint but have a hidden weather proofing system that carries away the water.

 

The next significant component of a dry ridge system sits between the ridges and the tiles of the roof slope. This part of the system usually includes a ventilated strip that ensures moisture laden air is vented from under the tiles.

Avoiding mortar

Whilst mortar certainly does the job, there are a number of disadvantages it is worth being aware of. Mortar has a limited lifespan and requires regular maintenance because it will deteriorate in time through natural weathering.