A village core and the concessions are two different roofs
New Lowell has a compact residential centre and a great deal of open country around it, and the roofing problem is not the same in both. In the village, lots are smaller, roofs tend to be simpler, and the job is usually a clean steel install over a straightforward plane. Out on the concessions the buildings are older and more exposed, often with outbuildings alongside the house, and wind is the governing condition rather than an afterthought. We quote them differently because they are different jobs, and the site visit is where that gets sorted out.