Slate Roof Repair

The removal and replacement of individual slates is an important part of maintaining a slate roof. Individual slates occasionally have to be removed and replaced due to damage by foot traffic,
fallen tree limbs, heavy snow and ice loads, stress cracks left over from the quarrying and installation process, and inherent defects in the slate itself. Individual slates are also removed, salvaged, and reinstalled in order to allow for flashing and/or underlayment repair and replacement.

When replacing individual slates, new slates should match the existing in type (region where quarried), color, weathering characteristics (unfading, weathering, semi-weathering), size, shape, and texture. It is especially critical that the size of the slate match the original in order to maintain the proper headlap and offset. The use of replacement slates that are too small can compromise the weathertightness of the roof. New slates may be used, but quite often a better match will be had with reclaimed slates of approximately the same age.

Copper nails, slate hooks, bibs, sheet metal hooks, and straps are most frequently used in slate repair work. Lead-coated copper and stainless steel fasteners and flashings are also commonly
used. The objective is to use materials with service lives equal to or greater than that of the slate itself. Note that galvanized steel elements will eventually rust and could cause staining of the
slate.

In all of the slate repair methods, the first step is to fully remove the broken or damaged slate. This is accomplished using a slate ripper. The ripper is inserted below the broken slate and hooked onto one of the nails holding the broken slate in place. The nail is pulled out (preferred) or its shank cut by first pulling down on the slate ripper and then striking the shoulder of the ripper with a heavy hammer (such as a claw hammer). The process is then repeated to remove the other nail(s) holding the slate in place. After all the nails are removed or cut, the broken slate will usually slide out. If it does not, the ripper or the pointed end of the slate hammer can be used to coax the slate out of position. Once the entire slate has been removed, the ripper can be used to clean any leftover broken pieces of slate, debris, or nail shanks out of the way so that a full-length new slate can be slid up into position. It is sometimes helpful to use a slightly thinner slate for the repair to ease its insertion.