Slate Roofing Repairs & Restoration in Sydney

Nail sickness: the classic slate failure

The most common reason old slate roofs start shedding slates is nail sickness. The original iron nails corrode over the decades until they no longer hold, and slates begin to slip and fall even though the stone is perfectly sound. You will often see a scattering of intact slates in the garden after a windy night.

Fixing slipped slates properly means refixing with copper or another non-corrosive nail, or using a slate hook (a copper tingle) where the slate cannot be re-nailed from above. Bodged repairs that just smear sealant over the gap are a warning sign of someone who does not understand slate.

Lead flashings and valleys

Slate roofs rely heavily on dressed lead flashings at valleys, chimneys, parapets and abutments. Lead is soft and long-lived but can crack from decades of thermal movement or from being poorly dressed originally. A lot of leaks on old slate roofs trace back to tired lead, not the slate itself.

We re-dress or replace lead flashings to match the roof, keeping the detailing sympathetic to the age of the building. Getting the lead right is usually the difference between a slate roof that leaks and one that stays dry.

When restoration beats replacement

Because the slate itself is so durable, many old Sydney roofs can be restored rather than replaced. That can involve refixing slipped slates, replacing the few that have delaminated, renewing the lead and repointing any mortar detailing. A full re-slate is a major job and only warranted when a large share of the slates have genuinely reached the end. We assess honestly before recommending the bigger spend.