Roof Covering: Tiles, Flashings, and the Details That Keep Water Out
PremiumWhat goes on top of your extension roof structure: tiles, flat roof membranes, lead flashing, dry ridge systems, fascia, soffits, and guttering. Covers the lead flashing failures that cause 90% of extension roof leaks, the roofer-window coordination problem, and a pre-payment inspection checklist no other guide gives you.
Do this first:
Tiles are the easy bit. Any half-competent roofer can hang tiles and nail slates. What separates a roof that stays watertight for 50 years from one that leaks within 18 months is the stuff nobody photographs for Instagram: the lead flashing at abutments, the soakers under every tile course where roof meets wall, the patination oil that prevents white carbonate staining, and the dry ridge clips that stop ridge tiles lifting in a gale. Ten out of fourteen forum threads analysed for this guide were about leaks at the junction where extension roof meets existing house wall. The tiles were fine. The flashing wasn't.
Your roofer's job is to turn the bare timber frame (covered in breathable membrane from the roof structure stage) into a fully watertight envelope. Once that's done, your electrician, plumber, and plasterer can start work in a dry space. The weather stops being your enemy. But if the covering is rushed or the details are wrong, you'll be chasing leaks for years.
Your roof structure must be complete with breathable membrane installed and inspected by building control before the roofer starts. If you have roof windows (Velux or similar), they should be on site before tiling begins. The roofer needs to tile around them, and the window manufacturer's flashing kit integrates with the tile courses. Missing windows means the roofer either leaves gaps (weather risk) or tiles over the opening (rework).
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