Box gutters and Valleys have been notoriously difficult to seal for many years.

Lead is valuable therefore prone to theft and also requires steps in the box gutters to allow for expansion.

Felt box gutters suffer from the effects of the sun and are prone to bubbling and splitting.

GRP (fibreglass) is an ideal covering for Box Gutters and Valleys. 

It's low expansion qualities allow for no steps requiring in the design and no joins or seems in the finshed surface.,