How to Repair a Slate Roof
by David Robinson
One of the unique features of a slate roof is that a slate roof is easily repairable. A slate roof is made up of thousands of individual pieces of natural slate. The combination of individual pieces of slate and separate flashing components allow repairs to be made in localized areas without replacing the entire roof.
Individual pieces of slate or areas of damaged slate can be replaced since the slates are not connected in anyway to the slates around them.This unique feature of slate roofs makes it important not to use roof cement or tar (not to mention caulk) to repair slate roofs.
Once small or large areas of slate are connected with roof cement, repairs become much more difficult and costly. Wherever possible, slates should be fastened to the roof using copper nails and hooks. Copper nails can be used when replacing a larger continuous area of slate. Hooks can be used when replacing individual slates.
Having the right tools for the job is the first step to correctly done slate repairs. For the most basic slate repairs, a slate hammer, slate ripper and a supply of slate hooks and 1 1/2" and 2" copper nails are necessary.
The slate hammer will typically have a small square end for hammering nails and slate hooks into place with a sharply pointed opposite end used for punching holes and scoring the slates. At the top of the hammer are two teeth used for pulling nails. Finally, the shank of the hammer has an edge used for cutting slates. A "T" stake is used for in conjunction with the cutting edge of the slate hammer for cutting the slates.
The slate with the hole in the middle needs replacement. Here a slate ripper is slid under the slate and the nails ripped or pulled out.The slate is held in with two nails. Hooks at the end of the slate ripper can be used to yank out or break the nails.
Here, debris is pulled out and disposed. The ripper is used to pull out any debris still under the other slates.
Here, a galvnized slate hook is installed. Some installers will use a stainless steel hook. We find that the stainless will remain shiny and catch the sun, resulting in an easily visible slate repair. The galvanized hooks will actually turn a dull gray and blend into the roof while at the same time, lasting for many years. Copper hooks have also been available, but they can be too soft to nail into old sheathing.
The completed slate repair. If a group of slate in a continuous area need to be replaced (above a leak for instance), the slates to the bottom of the group can be nailed and the slate few slates at the top can be hooked.