I want to replace the tiles on my roof with something different. 1. Can the replacement tiles be heavier than the original roof covering? 2. Can the replacement tiles be lighter than the original roof covering?

Building Regulations acknowledge that when stripping and re-tiling an existing roof the replacement tiles or slates may impose a substantially heavier load than the original roof covering. Also, there may be occasions when the new material imposes a substantially lighter load than the original roof covering.

If the replacement roof covering was significantly heavier then there is the risk that the roof structure may collapse if it is not designed to carry the extra weight. If an heavier roof covering is to be used, then a qualified structural engineer must carry out a survey and advise on any roof structure strengthening which may be required.

If the replacement roof covering was significantly lighter then there is the risk that the roof structure may be lifted or otherwise damaged in high winds. Many older roofs are not physically fixed to the building and instead rely on the weight of the tiles or slates to prevent uplift. If a lighter roof covering is to be used, then a qualified structural engineer must carry out a survey and advise on any roof structure strapping and bracing which may be required.