So, the shading warranty is really a guarantee that all shingles within the same lot will have the same appearance. It is not a guarantee that Lot 1 will match Lot 2. Sometimes Lot 1 and Lot 2 match other times they do not, and this is due to variations in the manufacturing process. Understand when manufacturing, the term “quality” does not mean every product is exactly the same… it means the product meets a predefined acceptable tolerance. This is why CertainTeed (as well as every other manufacturer) educates contractors to check the lot numbers on the shingle bundles and not to comingle. If you comingle, many of your homeowners will never know because those lots happen to match. However, do it often enough and you will eventually get burned and in the case of CertainTeed the manufacture will not consider this a defect because again they do not guarantee Lot 1 will match Lot 2… they guarantee that all of Lot 1 will match as will all of Lot 2.
Regarding “structural” I assume you mean the other warranties that are not concerning shading or appearance. If so, lot number has no bearing on this. However, frankly, you have problems there too. CertainTeed (as well as OC, GAF and all others) give a “basic” warranty that does not depend on contractor certification. This said, the contractor still has to meet certain requirements otherwise whatever issue comes up will automatically be chalked up as craftsmanship and not covered under the materials warranties. So, people have pointed out that this contractor used architectural shingles as ridge cap. Those people are correct, and you should check two things here. First, your contract with this contractor probably required they use hip and ridge shingles. If you don’t know… check it before you meet with them. Second, is CertainTeed requires that Shadow Ridge, or an equivalent, be used as hip and ridge shingles to qualify the roof for their standard wind warranty. In your case, you don’t have these installed, so you do not have the standard wind warranty. If you have any blow offs and attempt a claim the field rep will see from the ground that architectural shingles were used, get the drone out, to snap a picture and then tell you he regretfully informs you that you have no wind warranty as the contractor failed to follow their minimum installation standards.
Most on this forum will tell you the manufacture warranties are not worth the paper they are written on. On the whole, they are absolutely correct. The nuance is that this really is a regional issue as the field representative has a lot to do with what gets approved and what doesn’t. In my area, the CertainTeed rep is pretty good about standing behind his products while the OC representative, to my knowledge, remains undefeated in never approving a claim. I say this so that you understand roofing is more about skillset then some fancy warranty. The manufacturers are all bottom line driven and have an economic interest in disqualifying your roof’s warranty for any reason they can. While this is neither legal nor moral that is beside the point as they have some of the best attorney’s money can buy. Therefore, your best bet is to hire someone that will install a quality product in a quality manner so that you do not have to worry about ever using the manufacturer’s warranty. Very, very few roofs end up in warranty claims as compared to the ones with craftsmanship issues. Nonetheless, if you don’t meet minimum installation standards there is absolutely 0% chance of a claim ever being approved regardless how good the local rep is.
If I were you I would politely but firmly make a few demands. First, I would demand they install matching shingles. Second, I would demand they install Shadow Ridge on any hips and ridges regardless whether the contract specifically required it or not (assuming that it isn’t clearly written they were going to use architectural shingles for this purpose – this would be pretty dumb but who knows). My basis for the first demand is obvious. My basis for the second demand is pretty simple as well. They sold you a product and that product needs to be installed to the minimum acceptable standards. Otherwise, it is not a good install and as a contractor… I do not pay other contractors for bad installs… so why should you as a consumer? This isn’t a “good enough” situation. You paid good money for this and it needs to be installed correctly as per the manufacturer and local codes.
I’ve talked a lot about warranties and told you what I would do to resolve your immediate issues. However, my real concern for you, and I am sure many will agree with this, is the fact you hired a guy that left such an obvious visual defect and is so cheap that he cuts up leftover architectural shingles for ridge cap. In my experience, these are major indicators that this contractor has little to no pride in his work and/or is a complete idiot. Either way, the net effect is they probably over and/or under drove all your nails, did not 6-nail, have high/low nails all over the roof and I’m willing to bet their flashings are questionable at best. These are some of the most critical details of your roof. I am just raising this point to encourage you to have someone reputable look at your roof in person prior to settling up or signing any acceptance form as you have some serious red flags going on.