They can be used on any roof!
The brackets are spiked into the rafters/trusses and a batten laid across to create a working or access platform.
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Scottish slates are traditionally held in place on
the sarking by a single nail fixed through a hole
at the slate head. This is sufficient to hold it in
place, and resist wind uplift. Provided the proper
overlaps are observed, there is also less chance of
water penetrating through the nail hole.
With each single-nailed slate also trimmed at the
shoulders it is possible for individual slates to
be easily swung aside to allow access to carefully
remove the broken slate and for a replacement to
be nailed in its place. The overlapping slates can
then be swung back into their original positions
over the new slate to keep the roof watertight
http://www.historic-scotland.gov.uk/informguide-slate.pdf