Common Defects – Slate Roof Coverings

This is where we summarise the typical defects affecting slate roof coverings.

Nail rot (or nail sickness)

Unlike tiles, which have nibs that hook over the tiling battens, slates rely entirely on their fixing nails to remain in place. These days, copper or galvanised steel nails are used to secure roof slates as they do not deteriorate, but iron nails were common through the Victorian period.  As iron nails age, they corrode resulting in the slates slipping or breaking.

It’s difficult to replace individual slates as the batten in to which the nails are hammered will be covered by the slate above, which is still nailed in position. A strip of lead sheeting, known as a ‘tingle’, is therefore used which can be nailed in to a batten and extends down and hook around the base of a replacement slate.

Where multiple tingles are visible on the surface of a slate roof, it indicates that the nails are deteriorating and will require running repairs until the covering is replaced. Slate coverings secured by iron nails generally pre-date the widespread use of sarking felt so any damage will lead to rainwater penetration.

If you live in the Cambridgeshire of north Essex area and would like a quote for an RICS Home Survey, please contact us for a quote on 01799 543532 or via email.