Built-in box gutters
On many homes built before the war — in Webster Groves, Kirkwood, the city’s brick neighbourhoods — there is no gutter hanging off the roof edge, because the gutter is the roof edge. A metal-lined trough runs inside the cornice, invisible from the street. It is an elegant detail, and it fails in the least visible way a roof can fail.
A leak that never shows on the roof
The liner is the whole story. As long as its metal is sound and its seams are tight, a box gutter outlasts everything around it. But the liner works hard — it holds flowing water, standing water, and every thaw-refreeze cycle of a St. Louis winter — and when a seam opens or a low spot rusts through, the water does not drip into the yard. It goes into the cornice itself, then the rafter tails and the wall below, all behind paint and trim.
That is why box-gutter houses so often show their trouble indoors first: a stain at the top of a wall, peeling paint on a soffit, a corner of crown moulding that never quite dries. By the time the evidence is visible, the carpentry repair is usually bigger than the metal repair that would have prevented it.
The choice a replacement forces
When a roof with built-in gutters comes up for replacement, the gutters are part of the decision whether anyone raises them or not. Relining keeps the original architecture — a proper job replaces the metal, corrects the fall toward the outlets, and leaves the cornice as the builder drew it. Converting to hung gutters changes the look of the house and often involves rebuilding the edge, but simplifies every future decade.
Neither answer is wrong; what is wrong is a quote that ignores the question. A bid on a pre-war house that never mentions the gutter detail has either not looked closely or is planning to shingle around a liner at the end of its life — and the new covering will then depend on the oldest metal on the house. Ask the question directly and the quality of the answer tells you a great deal about the bidder.