As a slate roofing specialist, we have encountered many situations over the years involving slate roof repairs, faulty repairs and misinformation about slate roofing. In this section of our website, we will try to identify correct and incorrect methods of slate roofing repair and installation. While physically demanding, slate repairs are relatively simple. Repairs become more complicated than necessary, creating more headaches for homeowners, when tried and true methods of repair are avoided using shortcuts that turn out to be more time consuming.
Aside from safety and access equipment like ladders, jacks, harnesses, foam pads, etc, slate roofing repairs (and installations) cannot be performed without slater's tools. A slate hammer, slate ripper, T-Stake, copper roofing nails and galvanized slate hooks are essential (not to mention an appropriate replacement slate).
The picture to the left shows the key to proper slate repairs. A slate hook (shown at left) holds new, replacement slate in place. The old slate is removed using a slate ripper, a hook is driven into the roof deck, (not through the slate), and the hooked end holds the slate in place. This system works in most situations.
Where repairs go awry is when "roofers" decide that acceptable repairs can be made by other methods, including roof cement, face nailing, nail and bib, sheet hangers and gluing slate back together.
A common question is why don't we use copper or stainless slate hooks? Usually, the copper hooks are too soft to drive into old roof decking. While stainless steel hooks may last indefinitely, they remain shiny and stand out on the roof catching the sunlight on sunny days. If you like "bling" for your roof, then stainless hooks aren't objectionable. The beauty of galvanized hooks however, is that they patina to a dull grey and blend in with the slate, becoming hardly noticeable.
When you interview your slate roofer, ask what method he is going to use to repair your roof. For a further list of questions appropriate to slate repair, see "Buying and Maintaining a Home with a Slate Roof," by David Robinson.