The Nail & Bib Method of Replacing a Slate Roof

Roof Construction

• Slate tiles are installed in the centuries-old manner of hanging each slate by one or two nails. Cone-shaped holes are punched through the slate to accommodate the nails so that they hang loosely, yet securely in place. The conical holes house the nail heads, so they don't abrade the slate hanging on top of it. If you could pick up a house and shake it, a properly-installed slate roof would rattle.

Objective

• The goal of a nail and bib slate replacement is to hang a new slate in the old spot, so it hangs in the same manner as the original. When done correctly, and with a matching shingle, the replacement should be indistinguishable from the rest of the roof.

Supplies

• Only about 40 percent of a shingle is exposed, so look at the end of the row to determine the full length of the slate you're replacing. A shard of original slate helps you determine the correct thickness. Take a piece of old slate to the slate yard for an exact match. The slate will probably come with pre-punched holes that you won't use. You'll need 4-X-6-inch copper bib flashing and 1 3/4-inch copper roofing nails.

Tools

• All this is required is a hammer, a slate cutter and a slate ripper. If you get a slate that is the right size, you won't have to trim it. If you need to cut a slate, the slate cutter slices slate like a paper cutter. The slate ripper looks like an iron sword with hooks. It is slid under the old slate and grabs the old nails. A hard blow to the handle removes the nails, and with them, the old slate.

Installation

• Installation involves sliding a new slate in place of the old one. The new slate is nailed in place between the slot above it, using a single nail. The copper bib is then pushed under the slot, so it covers the nail and extends 2 inches under the course above it. The hidden bib makes the repair watertight and invisible.

Finding a Roofer

• If you are using a roofer, find one who specializes in slate roofs and takes pride in his work. Ask him the methods he uses to replace slates. Be wary of roofers who want to face nail exposed sections of slate and seal the nails with roofing cement. Always get a second option when any roofer tells you the roof requires total replacement.

Tips

• Stainless steel slate hooks are a durable and discreet alternative to the nail and bib method. They don't require punching a hole and using a bib. Always use copper bibs with copper nails. Dark-painted aluminum bibs and aluminum nails are acceptable, but not electro-galvanized nails, which rust over time. While replacing a slate is simple, it is not safe. If you're doing the work yourself, take all safety precautions associated with roof work. Keep in mind that slate roofs are steep, slippery, fragile and cannot be walked on.