Solar Panels on Slate Roofs

Why slate needs more care

Slate is thin, brittle and fixed with nails rather than hung on a nib. Anchors have to be placed carefully and the slate dressed or replaced around them. A rushed job on slate shows up as cracked slates and, eventually, water ingress.

The London context

Much of the older housing here is Victorian and Edwardian terraces, interwar semis in the outer boroughs, and a large stock of converted flats, with clay and concrete tile, London stock slate, and a lot of flat and butterfly roofs behind parapets. Butterfly and parapet roofs are common on London terraces and often suit a flat-roof frame rather than an on-roof rail system, and large parts of the inner boroughs sit in conservation areas.

Fixing detail

Anchors fix to the rafters, with the slate above dressed over the bracket or replaced with a lead soaker. Done properly there is no reliance on sealant to keep the water out.

Age and condition

Old slate can be sound for decades more or can be at the end of its life with failing nails. A survey should include a genuine assessment of that, because it changes the sequencing of the whole job.