Natural slate is one of the longest-lasting roofing materials there is. Quality slate commonly lasts 75 to 100 years or more, and some roofs in Atlanta's older neighborhoods have been on the house since it was built.
So when a slate roof starts leaking, the first question shouldn't be "how much is a new roof?" It should be "what actually failed?"
What usually fails first (hint: not the slate).
- Nails. Older slate roofs were often fastened with iron nails. When the nails rust through, slates slip out of place, leaving gaps.
- Flashing. Valleys, chimney flashing and wall flashing wear out long before good slate does, especially if they were steel instead of copper.
- Broken slates. Usually from foot traffic, falling limbs or careless work by other trades, like satellite or HVAC installers.
- Past bad repairs. Tar, caulk, or asphalt shingles patched into a slate roof trap water and make the next repair harder.
Signs a repair is the right call.
- Leaks are coming from specific spots: a valley, a chimney, a skylight.
- A handful of slates are cracked, missing or slipped.
- The slate itself is still hard and rings when tapped, rather than flaking or crumbling.
- The deck underneath is sound.
In these cases, replacing flashing (often with copper), resetting slipped slates and swapping broken ones can add decades to the roof.
Signs replacement may be needed.
- The slate is delaminating, flaking or soft across large areas. Some softer slates simply reach the end of their life.
- Widespread nail failure means nearly every slate is loose.
- The deck has rotted from long-term leaks.
- Years of mismatched patches and tar make the roof unrepairable.
Even then, the good slates can often be salvaged and reused on part of the house.
Matching slate.
Slate comes in different colors, sizes and thicknesses depending on where it was quarried. A good repair matches all three, using reclaimed slate from salvage or new slate selected to blend in. Unfading slates hold their color; weathering slates shift over time, so a perfect match may take some hunting.
Why slate needs a specialist.
- Walking slate the wrong way breaks it. Specialists use staging and ladder hooks instead of walking on the field.
- Slate is fastened differently. Replacement slates are secured with copper slate hooks or nails and a bib flashing, not glued in place.
- Flashing is custom work. Valleys, chimneys and walls on a slate roof are usually hand-formed in copper.
A crew that mostly installs shingles can do real damage to a slate roof in one afternoon.
Alternatives when replacement is needed.
If a full replacement is the honest answer, you have options:
- New natural slate for historic homes and owners who want a 100-year roof.
- Brava composite slate, which looks like slate from the street at a fraction of the weight, with strong impact resistance. See Brava composite roofing.
- Designer shingles with a slate profile, for a slate look on a shingle budget. See designer shingles.
How we approach a slate roof.
We start with an inspection from the attic and the roof, photograph what we find, and tell you plainly whether the roof needs repairs or replacement. Most of the time, it's repairs. See slate roofing and copper roofing for the flashing work that usually goes with it.
How long does a slate roof last?
Quality natural slate commonly lasts 75 to 100 years or more. Flashing and nails usually need attention long before the slate itself does.
Can you repair just a few slates?
Yes. Broken or slipped slates can be replaced individually with matched slate secured by slate hooks or copper nails.
Can I walk on my slate roof?
We don't recommend it. Slate breaks under careless foot traffic. Leave it to a crew with the right staging.
Is Brava a good replacement for slate?
For many homes, yes. Brava composite slate gives a similar look from the street, weighs far less, and resists impact well. Natural slate still lasts longer.
