Roofing

Building standards check for grp valley install

Anonymous user 12/11/2026 - 8.11 AM

Views on my questions to my roofer? I can't seem to add photos but I think he needs to have installed the grp on on a continuous timber valley which he's not done, overlap the membrane on top of the grp which he's not done, extend the lead flashing out 150mm onto the flat roof which he's not done, and seal the end of the grp with lead saddle wings which he's not done: Starts: Can I check a couple of details with you? 1. I remember you commenting on position of the membrane on another photo I sent you so I checked your photo and got this back: _According to standard GRP manufacturer guidelines and BS 5534, the membrane needs to lap over the outer edges of the trough (or sit over raised side battens) so any secondary water under the tiles is directed into the water channel rather than slipping underneath the valley._ What do you think? Is the above incorrect for some reason? 2. regarding the termination of the grp valley and lead: BS 6229 (Code of practice for flat roofs with continuously supported flexible waterproof coverings): Section 4 & Section 7 (Roof Detailing and Abutments): BS 6229 specifies that any pitched roof detail (such as a valley or apron) discharging concentrated rainwater onto an adjacent flat roof must incorporate an apron or flashing that extends horizontally over the flat roof membrane by a minimum of 150mm. From your photo it looks like the leading has been cut back rather than extending over the flat roof by 150mm? 3. BS 5534 (Code of Practice for Slating and Tiling for Pitched Roofs): Section 5.5.6 (Valleys) & BS 8000-6 (Code of practice for workmanship on building sites — Roof slating and tiling): Requires that open ends of dry valleys exposed to weather, change of pitch, or lower abutments must be protected with dedicated lead flashings or proprietary closures to stop wind-driven rain penetration under the tiles. Would Lead Saddle Wings (Sealing) be the appropriate solution where the lead is dressed up and over the side upstands of the GRP trough to wrap around the sides, blocking wind-driven rain from blowing sideways into the cavity under the tiles?