An Insidious Leak

Some roof leaks are harder to find than others. But leaks in the field of slate, away from flashings, or other obstacles, where there are no visible signs of a broken or missing slate are almost always caused by a failed or rusted bib.

Rusted sheet metal bib with nail head sized hole.

The potential for the bib to fail is one of the two flaws in the "nail and bib" method of slate roof repair. The other significant flaw is that when nailing the slate in place, the two slates where the nail is driven is, are invariably damaged. 

Damaged slates from a nail and bib repair. (not to mention source of leak)

On the other hand, a slate repair using a slate hook will never fail. Of course, one can't use a slate hook in every situation, but where it can be used, it should be used. I once heard of another contractor say he didn't use slate hooks because they "stain" the roof, yet he had no problem install big, galvanized #100 snow guards that certainly left a much greater impact. 

A galvanized slate hook. 

But I still don't buy that theory. Slate hooks leave very little visual impact on the roof, especially galvanized hooks. Some like to use the stainless steel version, but I find them jarring on a sunny day. 

Zoomed in on a slate hook on a sunny day. 

The photo above is a zoomed in picture of a galvanized slate hook. Kind of hard to see, and given the location of a hook - in the keyway, any run off staining is virtually non existent -- unless it is the zinc killing off roof mold, and then only slightly. 

That leak where no slate are visibly broken is likely an old slate repair. If no slate repair can be found, there could be another cause -- read about it here. 

Who is Trip Trapping Across My Roof?!?

Once, there was a slate roofer tapping and a tapping new slate into a roof. "Who is that trip trapping on my roof!" was heard from the ground!

Warning! NSFSR (Not safe for slate roofers)

People are totally unaware of what goes on thirty feet above their heads, yet I'm sure a check was written and cashed for the lousy workmanship shown below. For a very simple primer on how to correctly repair a slate roof, click here. 

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.