Steel Buildings in Europe

Part 1: Architect’s Guide 1 - 31 roof beams and is fastened with screws or bolts. The lapped sheets do not require a waterproof membrane; the panels are simply lapped, the higher above the lower on the slope. A typical arrangement of a pitched roof at the eaves is shown in Figure 4.3. It is important that the drainage system is adequate for the run-off from the whole roof. 1 1 3 2 1 Sandwich roof panel and sandwich façade panel 2 Roof slope > 6  3 Hot rolled or cold formed section Figure 4.3 Insulated sloped roof 4.3.2 Flat roofs Where the roof is flat, it must be fully watertight against standing water and it is therefore usual to apply a waterproofing membrane on its top surface. Where profiled steel sheeting is used, it is typically a deep profile, spanning between the primary structural members. Insulation is then placed on top of the sheeting, fixed with bolts or screws. The waterproof membrane is then applied on top of the insulation. An example is shown in Figure 4.4. Where flat roofs are provided, there is a risk of ponding. Water can accumulate in the central area if the roof deflects significantly. If there is inadequate drainage, water can also be retained by kerbs or other details around the edge of the roof. It is vitally important to minimise the risk of ponding by precambering the roof and providing adequate drainage.