The roofers appear to be nailing the slates without first countersinking the holes. Is this a new technique or are they being lazy? I expected them to knock 2 holes from the back of each slate so there's a 'countersink hole', or 'bevel', which the head of the nail will sit in and so not rub against the slate on top and (eventually) rub a hole in it.
Am I worrying unnecessarily, is there something I've missed, or must I have words with them before they fix any more slates to my roof?
[g]