How do I find replacement slates to match my existing roof?

Take a sample of the existing slate to a slate supplier and match by color, thickness, and texture. Vermont slate suppliers — Vermont Structural Slate, Camara Slate — maintain stock in a range of grades and can match most Vermont slate. For Pennsylvania and imported slate, the match may be less precise but still acceptable.

What is a slate ripper and where do I get one?

A slate ripper is a flat steel tool, 24 to 30 inches long, with notched hooks at the end that catch on slate nails when slid under a broken slate. It is pulled sharply downward to cut through the nails. Available from roofing tool suppliers.

How do I know if my slate roof needs to be replaced or just repaired?

A slate roof needs replacement when more than 20 to 25 percent of the slates are failing — soft, face-scaling, or breaking spontaneously. When individual slates fail from mechanical damage or fastener failure but the majority are sound, repair is the correct approach. Have a slate roofing contractor do a full condition survey before deciding.

Slate Repair and Individual Slate Replacement — Old Canaan Building Materials

The most common mistake made with a slate roof is replacing it. A slate roof that is losing individual slates is not failing — it is doing exactly what a maintainable system does: presenting individual replaceable elements that can be renewed without disturbing the rest of the roof. The correct response to a slate roof that is "losing slates" is to identify why individual slates are failing and fix that specific problem.

The Character

A maintained slate roof over time develops a slightly varied surface — replaced slates from a different quarry lot may be slightly different in color, individual slates may show different weathering. This variation is correct and is the visual record of maintenance. A roof that looks perfectly uniform has either never been maintained or has been recently replaced.

What It Is

Individual slate replacement is done with a slate ripper — a flat tool with notched hooks that slides under a damaged slate to cut the nails holding it, allowing the broken slate to be removed and a new one slid into place, secured with a copper "bib" — a copper strip bent over the lower edge of the slate above and nailed to the deck below the new slate. The bib conceals the nail and prevents water infiltration.

How It Behaves

A replaced slate, correctly installed with a copper bib, performs identically to the original slates around it. The bib method is the standard for replacing slates in the field of an existing roof. It is slightly less elegant than original through-nailed slates but is invisible in use and equally weather-tight.

Why It's Right

Replacing individual broken or slipped slates is the correct maintenance approach for a slate roof. A full replacement is warranted only when the slates themselves are failing across the majority of the roof — soft scaling, face delamination, widespread breakage — not when individual slates fail.

How To Get It

A slate roofing contractor — not a general roofing contractor. Ask specifically for experience in slate repair and individual replacement. The tools and technique are specific to slate work. A contractor without slate experience will damage surrounding slates during repair.

The Old Canaan Standard

Individual slate replacement using slate ripper and copper bib method, matching replacement slate as closely as possible to existing in color, thickness, and texture, for maintenance of Vermont and Pennsylvania slate roofs on traditional New England buildings. Do not replace a sound slate roof. Repair it.

Something missing from the archive?

Suggest a material →

Slate Repair and Individual Slate Replacement

Suggest a material.