Underlayment? Years of life for the shingles? Quantity of nails per shingle. (Factory spec not always followed)

Thanks, I will look into quantity of nails. Both are using the same shingles (GAF Timberline Lifetime). Company A is using DeckArmor as underlayment. B is using GAF Shinglemate.

Are you attached to shingles? I ask because at those prices and knowing that shingles last 20 to 30 years you are going to be spending a lot of money on just the roof for the time you are living there. There are alternative products that will last 50+ years that will cost you more initially but your not shingling every 20 years. If steel isn't an option there is a rubber product that looks like slate that is neat. I have never installed it and don't know if it actually lives up to its 50 year life rating but I have thought about using it. I am from ND so a 35 year shingle will last 20 if your lucky and I would never buy a lifetime shingle as it is a waste of money as ND winters will eat them up and spit them out just like any other shingle and then I have the headache of trying to get warranty out of them. In my world that just isn't worth the cost. I have shingled 15 year old roofs that had 30 year shingles on them and they where in terrible shape. The environment is just to harsh for them.

Things to look for. You should be using 4 nails per shingle if they use less then kiss those shingles goodbye when you get your next 50 mph wind. I use 30 lb felt on the roof as an underlayment as it holds up better then 15# felt and frankly you don't need the fancy roof armor that they try to sell unless some building department mandated it. There is no robot that installs roofs so hand installed is standard. Unless of course by hand install they mean they don't use nail guns and instead use hammer and nails. If that is the case right there is a big part of your price difference as the labor required to hand nail shingles is twice that of using a nail gun. And there is no difference. If you spend ten seconds setting up your roofing nailer you will get identical results and the nailer will be far more consistent.

Copper is unnecessary unless that is the look you want. Will it hold up better in the long run yes but I have roofs with 50 year old tin troughs that still don't leak. Done right both will work perfectly. A side note to that though again is location. If your in a high pollution environment aluminum may react to the environment more than copper.

In the end if it was me I would go with Company B and I would inspect their work as they go. If you see something odd stop them and ask. Contractors hate it but you get what you want at a more reasonable price and the contractor doesn't get an angry phone call from a homeowner after their roof blows away.

Thanks for the response! I had not considered anything other than regular shingles. Some of the houses nearby have slate, but that looks like it is an entirely different kettle of fish. I will look into some of these other options you mention. Since my original post I have spoken with a great contractor who did a lot of interior work when we bought the house - he knows Roofer B well and used him on the house for a limited amount of work. I'm going to have the contractor initially manage the replacement of a fair amount of rotted trim, then manage the roofing work with Roofer B, and then manage a painter who will be coming in to repaint the whole house. I will be monitoring it all very closely. This way hopefully it can be a somewhat integrated process and all the flashing etc. can be done right.

Sounds like you have some serious winters in ND!