I think – no I am sure I have been ripped off by my roofer. I had a lot of dry rot and 30 sheets of plywood had to be replaced. He charged me for 30 hours of labor to do it. He said it takes about an hour to replace a 4 by 8 sheet – that seems like way too much time on a simple moderately sloped roof
Hummm, the problem I have with this is that the "dry rot" (which is really wet rot that has dried out) could have been identified by the roofer BEFORE he tore your roof off leaving you with very few options for a quick repair. As a former professional home inspector, we'd find delaminated/moisture damaged roof sheathing all the time by simply inspecting the underside of the sheathing which is visible form the attic.
As for the labor charges, I'm not really sure. If this guy worked by himself, it MIGHT take an hour to replace a sheet, but even that sound's like a lot. Did your contract establish any prices for sheathing that might need to be replaced? Also, if the sheathing was rotted, that can only mean that you need to improve your attic ventilation so that it doesn't happen again.
To gage as to whether you got ripped off– after ascertaining 30 sheets needed to be replaced– look at the labor rate and the cost of materials. Around here the going rate for sheathing replacement during a re-roof is $100 a sheet.
Home inspector & Author
Thanks to Jim and Tom for responding. I have a new piece of info. When asked the roofer supplied me with an invoice of materials used to fix the dry rot. The problem is the list does not match what was installed and when I went directly to the supplier – he sent me an invoice that clearly show my roofer falsified the invoice he sent to me.
If he lied here – I can only assume he lied about the time it took to repair the dry rot damage. And Tom you are right the problems came from lack of vents – I added 14.