Uninspired Methods of Slate Repair

It seems as that if you ask five different slate roofers what is their method of slate repair, you'll get five different answers. Way back when our company started, the slate quarries recommended using hooks for slate repairs. The logic of their suggestion to use something so small, inexpensive and simple to hold a replacement slate onto an existing roof seemed to make sense and nothing I've seen since has surpassed the functionality and simplicity of the slate hook. Roofers have used other methods for replacing slate, but as some of the other methods are illustrated, it becomes clear they are needlessly destructive or complicated.




  Here are some common methods used to repair slate roofs:

• Copper hanger
• Nail and bib
• Roof cement
• Face nailing w/caulk or roof cement
• Caulk
• Slate reconstruction

Notice I said common and not correct. Also, I've left off "slate hook," which I'll address in a separate post. Let's address these methods here. 

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1. Copper Hanger

Of the methods on this list, I could almost agree this one is not so bad and copper hangers or copper straps are probably the closest method of repair to hooks. 

(image 1) Single folded copper tab.

These tabs are installed a lot like hooks. Except some worker on a rainy day sits and cuts strips of copper. These hooks are nailed into the roof and the tab is created by folding the copper up over the front of the slate. In most cases, the copper is folded over creating a double layer strap. Unfortunately, these tabs are not always consistent and both single layer and double layer copper tabs will be present on the roof. The main problem with copper tabs is that they will often unfold when snow or ice sits on the roof. Once the tab unfolds, the slate will slip out. 

 (image 2) Double folded copper tab. (same roof)

 (image 3) Unfolded copper tab.    

The copper tab in image three was the first thing noticed when examining the slate This tab is starting to unfold and eventually, the slate will slide out.  On the same roof, there are two previous repair that were done with slate hooks. They are a little harder to see, especially from the ground. These are galvanized hooks, which turn a dull gray and blend into the roof very well.

(image 4) Slate hook. 

2. Nail and Bib

Among the most frustrating and commonly used methods of slate repair. A replacement slate is slid in place. The keyway (space or slot between two adjoining slate) is unabashedly damaged by the roofer when nailing the slate in place. See the "dimple" created in the two adjacent slate? Also of note, the nailhead is visisble.  A sheet metal bib is then placed beneath the two above adjacent slates to cover the nailheads. Unfortunately, the damage from the careless application of the nail is etched in stone. 

In this instance, the bib rusted away resulting in an unfortunate leak. Some of these leaks can take a while to find the source. 

(image 5) Nail and Bib

Rusted through bib. No, these cannot be used to view the solar eclipse without damaging your eye. However, these will result in a damaged ceiling, after which you might be seeing stars when the repair bill arrives. 

(image 6) Rusted Bib

Caulk

Roof cement and other sealants should not be used on slate roofs, except in specific circumstances, like the installation of a ridge or hip. Nothing says quality like roof cement on a slate roof.

(image 7) Roof cement. 

(image 8) 

(image 9)

Glued Slate (slate reconstruction) 

Probably the most unusual repair. Chips of slate are glued together on top of the slate. This repair was done by a big, well known roofing company outside of Washington, DC on house that was being sold. The buyer had the sense to have a slate roofer inspect the roof, rather than just the home inspector. 

As you can probably tell, common sense would suggest there may be a better method to repair these roofs.