Why Important
A well-slated roof can last up to 150 years. Regular maintenance is the key to keeping your roof performing well, avoiding unplanned and expensive emergency repairs.
The more complex the roof, for example with dormers or hips, the greater the likelihood of problems.
Originally, nailed slated roofs were fixed direct to the sarking boards.
What to look for
In order to avoid wastage, all sizes of slate were used and varied considerably in length and width.
If large numbers of slates start slipping, look along the course (row) of slates. If the line is very uneven the roof may be ‘nail-sick’ which means the fixings are failing, probably rusting. In this case it may be wise to consider re-slating the roof.
When to look
Check the roof regularly for slipped slates which allow water to penetrate to the timbers below. Slates can easily slip down if their fixings have rusted or the slate has broken due to wind uplift or foot traffic over the roof.
How to fix
The slater would sort the slates by size, working upwards from the eaves of the roof using the largest slates first then fixing in diminishing courses up the roof, with the slates at the ridge being the smallest.
If a slate is broken, a replacement slate will be needed which should match in type, texture, size and thickness.
If the roof is generally sound, the odd slipped slate can simply be re-nailed in place. Slates should always be fixed with broad-shanked copper clout nails; ferrous nails will rust and the repair will fail sooner.
Avoiding creating problems
Mixing different types of slates causes problems and must be avoided. If found, the odd slates should be replaced with the more prevalent slate style on that roof in order to avoid rain penetration into the building. Avoid using Welsh slates with Scottish slate roof as they will stand out visually.