The GRP dry bonding strip forms a continuous gutter above a party wall to create a watertight junction where roof finishes differ. Lightweight and flexible, it is easy to cut and slide into position without wet trades, and provides clean drainage that resists wind‑driven rain. UV‑stabilised GRP construction offers durability, while sanded zones provide a positive key for mortar where required. Fire‑tested to BS 476, the system is an efficient alternative to lead for reroofing or mixed‑finish refurbishments.