> the slate roof beneath the asphalt shingle roof that had been 
> power nailed through the slate roof.

How do contractors make these kinds of decisions? I can see it now:

Client: My slate roof leaks. Can you fix it?
Contractor: Sure. We have these handy, dandy asphalt shingles we can stick
up there real quick. It will make the leaks go away like magic.
Client: Are you going to remove the slate first?
Contractor: Nah. Our nails will fly right through the slate. The cracking
sound is pretty cool too. I love that cracking sound! You don't want to deny
me the pleasure of that sound, do you?

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>