The choice of roof structure depends above all on the roof geometry and the intended use of the attic, not on the weight of the covering alone. The building owner should check whether the design specifies the arrangement of load-bearing elements, connections and bracing, and whether the scope of work covers a complete solution rather than timber alone. It is also worth establishing how the material and connections were matched to the specific loads. This article explains these relationships and shows what to look out for when planning, purchasing and accepting the structure.

Whether a roof structure is safe depends not only on the selection of cross-sections but above all on checking the entire load path from the covering through the truss members to the supports. It is worth verifying that the layout matches the building span and the attic plan, and that the connections and anchorages transfer forces without displacement. When replacing the covering or changing the attic function, an assessment of the existing structure by a designer is essential, taking into account the new loads and support conditions.

The choice of substrate and underlay depends primarily on whether the roofing system requires full boarding or just a batten grid. This article gives you the criteria to assess whether a membrane is suitable for contact with insulation or a rigid substrate, how roof pitch affects requirements, and why ventilation and vapour control matter. Check how the selection of these elements affects the roof's ability to dry out and what consequences changing one of them has. Remember that design decisions remain with the designer.