Did you know?
Scottish slate is our most common traditional pitched roof covering and has been for many centuries, originally on castles and grand houses. In Scotland, slate was used more commonly from the 18th century depending on location. In Stirling, slate from quarries along the Highland Boundary fault (commonly referred to as Aberfoyle slate) was used. Depending on the age of your building it may have a different slate. For example Welsh slate became more common from the end of the 19th century when rail transport was possible. There are other traditional coverings such as pantile and Rosemary tile. Scottish slate is no longer quarried so repair relies on stocks of reclaimed slate. For more information on different slates and available options for slate repair please contact the TBHC team.
Slate is very durable and can be expected to last for up to 100 years or more. In Scotland, slate is traditionally fixed to timber sarking boards using a single nail at the head of the slate. The top edges of the slate are trimmed to form ‘shoulders’. This allows individual slates to be swung to one side to allow access to remove and replace any broken slate without disrupting those surrounding it.
What to look for
- Missing and slipped slates
Look for a gap in the pattern of the slate covering or slates sitting in gutters. This is generally the result of bad weather. Slates cracked by wind uplift.
- Broken slates
If you have a number of broken, fractured slates or pieces coming off the roof or into the gutter the slate may be reaching the end of its useful life and becoming ‘soft’. As a natural stone, slate will absorb water over a very long time and eventually start to break.
- Nail sickness
The original nails used to fix slates were often made of iron or poor quality galvanised steel and will corrode over time. Corrosion can cause nails to snap allowing the slate to slip. When this can be detected in a number of slates across a roof it is termed ‘nail sickness.
- Misaligned slates
Slates may have slipped out of line with the pattern of the roof. This may be due to nail breakage or enlargement of the nail hole as a result of natural decay
What to do?
Check your roof covering at least once a year and after severe weather. An initial inspection can often be done from the ground aided by binoculars or with a camera with a good zoom lens.