Impact-resistant is a real decision, not an upsell
Where hail comes through most summers, an impact-rated shingle is worth weighing on its own terms: it resists the bruising that strips the granule layer and shortens a roof's life without ever making it leak.
It costs more up front and it is not armour — a large enough stone will still mark it. Some carriers reduce a premium for one, which is worth asking yours about before you choose rather than after.
Brick changes where the roof ends
The city and inner-ring stock is brick, and brick means chimneys, parapets and party walls rather than a simple gable end. Each is a junction properly flashed and cut into the mortar, and each is a place a roof leaks when it was sealed instead of flashed.
Where the tuckpointing is spent, new flashing into failing mortar buys less time than it should. We would rather tell you that before the roof goes on.
The seasonal swing works fasteners and seams
The spread between a St. Louis summer and a St. Louis winter is wide enough to move a roof through a real range every year. Fasteners back out, laps work against each other, and details that were adequate on the day slowly stop being.
It is an argument for fastening to specification, and for details that do not depend on a bead of sealant staying flexible for twenty years.
Low-slope sections on the older stock
Rear additions, porch roofs and dormer tops on the city stock are frequently close to flat while attached to a steep main roof. They are a different assembly and they fail first when they are shingled as though they were not.
Those get their own system and their own line on the quote. The mid-century ranches through Affton, Mehlville and Oakville are simpler — long runs, one pitch — and price accordingly.