How to repair a slate roof

Once the nail is in the notch, a few hits with a hammer
on the offset handle of the slate ripper shears the nail
and allows the slate to slide out.

Slate is one of the most durable roofing materials available. Slate is so durable many slate roof repairs are necessary because of failures with the fasteners, not the slate itself.

Other common causes of problems with slate roofs are gutter straps nailed through the face of the slate and improper repair techniques.

The easiest way to assess if a slate roof needs to be repaired is with a visual inspection. If you see broken or missing slate, repairs are needed.

PROBLEM: What tools should I use to repair a slate roof?

Solution

Repairing a slate roof is a little more involved than repairing an asphalt shingle roof and requires a few specialty tools, including:

Ladder ridge hooks are attached to a single section of an extension ladder and hook over the roof ridge to secure the ladder in place.

• Ladder ridge hooks – One of the more difficult aspects of a slate repair is getting on the roof and getting to the area that needs the repair. Slate roofs are usually steep and walking on old slate roofs is not advised. Ladder ridge hooks are attached to a single section of an extension ladder and hook over the roof ridge to secure the ladder in place. There are small casters on the front side of the ridge hooks so the user can easily maneuver the ladder section up and down the roof. Note: most ridge hook manufacturers recommend using two ridge hooks per ladder.

• Slate ripper – A slate ripper is a tool with a long, thin metal blade that has notches on the end. The blade slides under the piece of slate and the notch catches on the nails holding the slate. Once the nail is in the notch, a few hits with a hammer on the offset handle of the slate ripper shears the nail and allows the slate to slide out.

Once scored, I line up the score mark with the edge of a piece of plywood and strike the slate with the edge of the brick trowel to break the slate on the mark.

• Slate cutter – A slate cutter is a shear designed for cutting slate shingles. The cutters are fairly expensive and hard to justify if you only do occasional slate work. What I use instead of a slate cutter is a straight edge, a carbide-tipped backer board scoring knife, and a brick trowel. Using the straight edge as a guide I score the slate with the scoring knife – three or four passes is usually enough. Once scored, I line up the score mark with the edge of a piece of plywood and strike the slate with the edge of the brick trowel to break the slate on the mark.

PROBLEM: How do I repair a slate roof?

Solution

The alternative method of attaching new slate
is with a slate hook. These are metal hooks (either
stainless steel or copper) that have a sharpened
end to nail into the roof decking or slats and
a hook on the bottom that the slate slides into.

To install the new pieces of slate on the roof, you can use the nail-and-bib method or slate hooks. With the nail-and-bib, the new piece of slate is slid into place and fastened with a nail in the slot between the pieces above the new slate.

Then use a cordless drill and 3/16-inch bit to pre-drill a nail hole in the slate to prevent the piece from breaking.

Next comes the bib; this is simply a small piece of metal flashing that you slide under the slate to cover the nail.

Placing a slight bend in the middle of the bib provides enough tension to hold it in place, but as an extra precaution, put a small dab of roofing tar on the nail head before sliding the bib into place.

Slide the new slate into place but slide it up higher than
it needs to be, nail the slate hook into place with the
bottom of the hook where you want the slate to sit, then slide the new slate back down into the hook.

The alternative method of attaching new slate is with a slate hook. These are metal hooks (either stainless steel or copper) that have a sharpened end to nail into the roof decking or slats and a hook on the bottom that the slate slides into.

With this method, slide the new slate into place but slide it up higher than it needs to be, nail the slate hook into place with the bottom of the hook where you want the slate to sit, then slide the new slate back down into the hook. The pieces on each side of the new piece prevent any side to side movement and the hook keeps the slate from sliding down.

–By Chad McDade, Housewright Construction, East Palestine, Ohio

What you’ll need

• ladder ridge hooks
• slate ripper
• slate cutter or backer board scoring knife and brick trowel
• cordless drill and 3/16-inch drill bit
• roofing nails
• hammer
• slate hooks
• roof tar
• metal flashing