My wife and I recently moved into our first home. It's a raised ranch in CT that was built in 1967. I've been doing a lot of "refreshing" myself inside; however, I hired a roofing contractor to replace our end-of-life roof. It was a two-layer job, so we had to go with the rip-and-replace method. The contractor I hired is local and well established (32 years). He gave us a quote for the full rip and replace including new drip edge, vent boots, tar paper and 6 feet of ice blocker. He also had as a line item an additional cost for any plywood that would need to be replaced.
The roof has what I assume to be its original 3/8" plywood sheathing and two layers of shingles (sounds about right: if you figure each roof lasted twenty years or so, the math works). Regardless, we purchased new GAF Timberline shingles and he went to work. The whole job took him (and his crew of two others) two days to complete. He told me that all the plywood looked great, there was no rot, and nothing had to be replaced. "Great", I thought.
That brings us to tonight. I went up into the attic to put some stuff up there and started looking around. It's fairly obvious to my untrained eye that the plywood is delaminated in some areas. I would've gladly paid the extra money to have the plywood replaced (even all of it if need be) to have a solid roof that would last 30–40 more years. I now fear we have great new roofing shingles over old crappy plywood that won't last. Our biggest fear is that if we eventually sell the house the inspector will say that the roof sheathing is no good and needs to be replaced.
I immediately placed a call to the contractor when I noticed this, however it was already 10pm tonight so I was unable to reach him. I assume he'll call me back, but I'm looking here for advice and guidance if anyone has experienced anything like this in the past. I'm not sure what I should or could expect from him at this point in the game.
I did realize that I had never noticed the delamination in the attic before. I'm thinking that the driving of all the new nails through it, plus the foot traffic on the roof made it much more noticeable. It's not horrible (there aren't pieces of the outside laminate falling off), but there are definite spots where the nails have ripped chunks out, and there are areas you can press on and just feel the spaces between. It's also very flexible and spongy between the rafters, so much that you can deflect it with you hand pressing outwards fairly easily.
Best Answer
I wouldn't worry too much about it. The plywood is not typically supporting a load of more than the paper and asphalt shingles that were placed, even more so if you have a considerable pitch on your roof to where it would be difficult or impossible for a person to walk on. It basically serves so that you have something to nail the shingles down securely.
Most newer homes use plywood, I have an older home that used what looks like rough cut deck planks and those are mostly still original. The last time I had my roof replaced, they had to change out a few boards that were terribly dry rotted and some that were badly damaged from previous water damage by the oh-so responsible homeowners who had the home before me. Other older boards look noticeably damaged by the most recent nails but they continue to hold down the shingles and I would still feel safe to stand on my roof.
As long as the shingles are doing their job then the plywood will not be exposed to any water, and as long as your attic has good ventilation during the summer time then you should have nothing to worry about for the next 15-20 years at least.