Other roof issues

Plain tiles are laid double-lap, so that 1 tile overlaps 2 courses below. They are fixed either by nails or pegs on battens. Some designs have nibs to hook over battens. Often a lime mortar torching is applied inside to help improve watertightness.

The corrosion of nails or the decay of pegs and battens due to insect or fungal attack will cause tiles to slip or crack. Slipped or broken tiles can be reinstated by sliding in replacements up over the battens or laths. They can be torched with mortar as before and nailed, if necessary, to secure them.

Practical difficulties arise when trying to match tiles of this era. Poor matches or the use of incorrect second-hand tiles can be regarded as inappropriate repairs to listed buildings. A policy of replacement needs to be developed if a single roof shows signs of progressive tile decay, and funding sought for appropriate replacement when enough tiles can be salvaged. Standard modern plain tiles are very unlikely to match early plain clay tiles, but matched batches can be made to order by specialist manufacturers.

Tiles can delaminate by frost action. This is usually made worse where water is retained on the roof by moss, lichen or leaf mould. This should be gently cleaned off when gutters are cleared.

Water ingress is usually due to slips, cracks and gutter overflow, and minor maintenance to rebed lime mortar fillets (or replace cement fillets in lime) will hold off the majority of problems. Lead flashings were not prominent original features, and retaining the lime fillets can help keep the character.

When reroofing or increasing insulation, the replacement of torching with modern sarking felts needs to strike a balance between retaining historical features and avoiding the danger of impaired ventilation. The use of modern nails and venting systems can be justified, but needs careful handling. The reuse of as many of the existing tiles as possible is preferred, and on larger estates the storing of removed tiles makes for a useful supply of spares.