About 9 years ago the two 20 year old skylights on our 120 year old house started to leak, and the 15 year old shingles looked wavy, and we reluctantly began to think, a little, about getting a new roof.
Over a period of 9 years or so, we had 7 or 8 roofers come by and give an estimate. All but two said the same thing: $5000 more or less; $6/sq foot for plywood as needed.
The first of the two exceptions was a two-man outfit who told me the house had to have plywood nailed on before the shingles went on and that the job would cost about 7500 (this was about 8 years ago).
I remember thinking that they fellow must be crazy since everybody else gave a figure of 5000.
But we didn't do anything about the roof except to put down a plastic bucket and, later, two plastic buckets, when it rained.
Finally, our next door neighbour had her roof done. Her house is a twin of ours and is the same age. She told us it was costing her 9000+ and they were going to sheath the house in plywood before putting on the shingles. We thought that must be an unnecessary expense since all the other guys only used plywood as needed.
While that job was going on, we thought maybe it was time to get the job finally done, and called in a big local outfit that had a good reputation according to the local newspaper poll.
The salesman was adamant that in a house as old as ours, it was necessary to sheath the roof in plywood; and that as a standard thing they then added felt, followed by the shingles. He quoted a figure of 9000+
We were shocked at the cost, but not quite as shocked as we would have been if we hadn't seen the work being done on our neighbour's house: I could see that they were using plywood and felt, and I could see that the exposed roofboards looked like hell. I couldn't tell what ours looked like because our attic is finished, but it seemed reasonable that they would be in similar shape to those of our neighbour.
We called in another outfit that had also been given good marks in the poll. Their salesman quoted the usual 5000/$6 per sq foot. By now, I had a slightly different perspective and asked him if he thought felt might be good to put on the roof before the shingles. He said that would be good since it would make the roof 'smoother' - this is without any mention of plywood. I then asked him about sheathing in plywood and he said that could be done for $1900 or so.
After that, I realized that a roofer who is willing to be honest with you about what is needed for a proper roofing job is a rare bird, and we decided to have the first outfit do the job.
The roofers arrived in late March. They took 4 days to do the work, and when I called to point out a small, almost invisible, 'skirt' they had missed, came back the next day to finish. The gentleman who does the flashing showed up the next day to flash the chimneys and back porch. The roofing team was helpful and pleasant. All in all, the company could not have been more professional, or exhibited more knowledge of the ins and outs of the business, including how to make it as painless as possible for the homeowners.
Given my vast ignorance, I feel we dodged a bullet and were damn lucky to find the outfit that finally did the job.