GFRP upstands with gutter are designed to be used with continuous skylights, thermoformed tunnels and ribbed tunnels as they are made with modular elements in order to obtain long length structures. They are realized with glass-fibre reinforced polyester, white pigmented on the internal side and designed to collect possible condensation water. They are insulated with rigid expanded polyurethane panels, density 35±1 kg/m3.