When ‘Brazilian slate’ fails: lessons from a Whitby re-roofing project

At White Lodge in Whitby, a roof covered with “Brazilian slate” and installed around 2010 failed under coastal conditions. Despite its relatively recent installation, it lost a large number of slates during a storm.

Positioned on Whitby’s West Cliff, the property is highly exposed to strong winds, driving rain and salt-laden air. Such conditions place significant demands on the durability and integrity of any roofing material.

According to Sam Lawson, director of Prodigy Roofing, the existing roof was not suited to this exposed environment. With over 25 years of experience, he identified clear durability issues, noting

The ‘Brazilian slates’ were not sufficiently durable and were prone to shattering.

So-called “Brazilian slate” in the UK and Irish market does not correspond to true metamorphic rock from a geological perspective. It is actually a different type of rock: metalutite. It is a lower-grade material with a documented record of reduced durability in demanding conditions, as reflected in recognised UK guidance such as the NFRC Guidance Note (GN66).

This project highlights how lower quality “Brazilian slate” can perform poorly in demanding environments. While it may appear suitable at installation, its limitations quickly become evident under sustained wind, moisture and coastal exposure. In such conditions, the quality and geological characteristics of the material are critical to long-term performance, as documented in the Technical Report on Brazilian Metalutite. 

Following the failure, Prodigy Roofing was appointed to carry out a full replacement. The existing roof was stripped and rebuilt with a new membrane, 2×1 roofing-grade battens, and a new slate covering.

For the replacement, Sam Lawson selected our CUPA R12 based on his experience with the product across multiple projects. As he explains:

I consistently use the CUPA R12 range due to its proven quality and performance.

The new slate roof has transformed the appearance of the property while providing a long-term solution suited to its exposed location. The homeowners were highly satisfied with the result, benefiting from a 100-year guarantee on the slates and a 25-year workmanship guarantee from Prodigy Roofing.

This project underlines a simple point: not all slate performs the same, particularly in the demanding weather conditions of the British Isles, where material quality is critical over time.

To learn more about the differences between true natural slate and so-called “Brazilian slate”, and how to specify materials for long-term performance, contact us and our team will be happy to guide you.