Correct. On most modern roofs we use a dry ridge system, which mechanically fixes the ridge tiles rather than relying on mortar alone. Dry ridge systems are designed for long-term outdoor exposure and avoid problems such as mortar cracking, loosening or deteriorating with age. Mortar still has its place, for example being used for flaunching around a chimney pot, or in heritage builds.

Dry ridge systems might look like “cheap plastic, but this is far from the case. Roofing-grade plastic is completely different to what you might see in day to day use, and is specifically engineered to resist cracking or warping under changes in temperature, frost, UV light and moisture.