Those holes were caused by the nails Robert. Though they only sat up 1/16" or so, the slate were so soft they popped holes.
I’ve never seen the galvanized nails cause issues other than rotting away and allowing the slate to fall offf the buildings. Same for straps. I seem to have lost a complete folder of the issues shown here in the OP.
I only found one similar pic where the iron particles in the slate were rusting themselves out. The copper nail is about to be set for a repair sequence I was photograghing.
That is what I thought.
That is why I mentioned look at where they are placed and mentioned galvanised nails.
The heads rust and fall off. The protrusion left behind from the fastener will ware away the slate on top.
Good slate is expense. There are many thickness for roof pitch and load capabilities.
The link I left behind talk about imports from INDIA, CHINA AND SPAIN if I am not mistaken.
The same with galvanised straps for roof jacks left behind they will ware away the slates on top.
I was looking for galvanic reaction.
Between stale. galvanized and minerals in slate. Rare but it can happen.
Iwill dig deeper.
I lost a bunch of folders.
I am happy you formed a hypotheses.
Frank how old is that roof?
Galvanic reaction makes sense.
Both roofs I posts pix of were about 120. Vermont slate on both.
BY comparison, here’s another 120+ year old roof with Buckinghams. Bad repairs notwithstanding, the biggest issue is rusted and completely gone galvanised nails. The slates are sliding off.
Depending on which order they loaded, the last one even has a portion of a galvanized bib sticking out from under a slate. It’s at least 60 years old. No harm to the slate above or below it.
I have a long video at G+ if you want to see it.https://plus.google.com/103247743251122058592?hl=en
BTW, do not seal slate! It just closes the keyways and causes leaks.
I enjoyed theslate repair tutorial, Frank. Thanks.
Excuse me for not saying the same, Thanks Frank.
Yes slate does last some time when maintenance and installed properly.
I do not miss working off of 3/4 inch hemp rope tied to my waste on 18/12 pitch roof decks. my Boss use to use as one point PPE, HA HA HA.
Nick had a thread asking about pitch and slope. Did anyone know the difference.
I posted a short explanation.
Pitch is vertical and slope is geometry degree of the run.
Have not seen you for some time Frank. Weren’t you a full INACHI member?
Hope all is well.
Hey Robert! I’ve been swamped here and falling behind with the workload and a series of operations on my wife. She’s doing fine. For some unknown reason, I can’t reply to your PM’s. Maybe you can get that lifted?:neutral:
I wasn’t a full member, but had more time to post. I owe Kenton some hi-res pix if I ever get back to that random slate job. It’s been a year!
Yes I vaguely remember your wife being ill and the doctors did not know why. My prayers are with you and yours.
I will lift my PM.
I will try to tell Kenton about your HI res. photos.
He gets busy Frank. I know he does mean to reply to everyone.
All the best.
Again God bless you and yours with health and happiness.
Done Frank. You can send a message any time. PS: Busy tonight. Remind me another day and I will hunt down Kenton and get your message off to him.
Sorry to hear about the Wife Frank!
I hope things are getting better!