GRP Bonding Gutter (Secret Valley)

Giving a weathproof seal between adjacent roofs


Product Information

GRP Bonding Gutter, also know as a 'secret valley', gives a weatherproof seal between adjacent roofs. It will join any combination of double lap or interlocking Slates, along with clay and concrete Tiles, with minimum disturbance to the adjacent roof.

The Bonding Gutter is manufactured from a glass fibre/polyester laminate with a UV-resistant polyester film on the upper face. A sanded strip is bonded along the upper face to provide a key for bedding the roof tiles into the mortar.

A Dry Fix Bonding Gutter can be used as an alternative, which eliminates the use of mortar.


The packs should be stored flat, on a smooth, clean, dry surface; under cover and protected from sunlight.

Dimensions:-    3000mm long x 216mm wide

Pack Size:-        10 per pack

Pack Weight:-  16kg per pack

Material:-          Glass fibre/polyester. UV resistant.

Bonding Gutter is a lightweight and flexible product, used on a daily basis by roofing & building contractors, and would be recommended as a stock item.


The end tiles or slates on both roofs should be removed to expose the construction over the party wall. Before fitting, it is advisable a fire stop is fitted to the top of the party wall, to ensure that the fire cannot spread between the 2 buildings.

Starting from the eaves, lay and fix the bonding gutter using clout head nails at approx. 1mt centres, ensuring the sanded strip is situated centrally over the party wall. Consecutive lengths of the jointing strips require a minimum lap of 150mm.

A mortar bed is applied to the sanded strip. The slates or tiles are fixed on both sides, ensuring they are located and butted up centrally over the bonding gutter. It is important the mortar does not enter the water channel of the slate or tile.


A BBA certificate can be viewed by clicking here .        


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