GRP Building Products A comprehensive range of Glass Reinforced Polyester exterior features for the discerning house builder market –from stock or bespoke. The collection includes Door Surrounds, Chimneys, Canopies, Porches, Porticos, Dormer & Bay Windows, Fascias, Copings, Planters, Columns, Dentils, Cornice, Dovecotes, Bell Towers – all the exterior features that define a special Home.