The sheet metal worker handles the transitions. Wherever one surface ends and another begins, at chimneys, dormers, wall abutments, roof edges and window sills, sheet metal directs water onward in a controlled way. These junctions may make up only a small proportion of the roof, but they are crucial to its watertightness: most leaks arise not on the main surface, but in the details.
They fabricate and install gutters and downpipes, chimney and dormer flashings, wall and roof-edge terminations, window sills, parapet cappings and sheet metal cladding on the facade. Much of this is made to measure in the workshop, because every building has different angles and dimensions.
Galvanised sheet steel, aluminium, copper and stainless steel differ in lifespan, price and appearance. More important than looks is compatibility: different metals in contact or in the same water run can accelerate corrosion, for example copper runoff over galvanised sheet metal. A specialist firm will check this too; a quote that only gives the price per linear metre usually will not.
Almost all water ingress on a pitched roof starts at a junction: at the chimney flashing, at the wall abutment of a dormer, at the transition to a roof window or at a blocked gutter that overflows. If your roof is leaking, have the junctions checked first, not the main surface. That is the quicker and cheaper order to follow.
Ask for linear metres and item quantities to be shown, not a single lump sum for the roof, and clarify the material including sheet thickness. Check whether removal and disposal of the old parts, scaffolding and tie-ins to existing building elements are included. Record who is responsible for the interface with the roofer so that no junction is omitted between two quotes.
Gutters should be cleaned at least once a year, or twice if there are deciduous trees nearby. An overflowing gutter soaks the facade and the plinth, and this damage often only shows up years later as moisture in the masonry. A leaf guard reduces the effort involved, but does not replace inspection, because fine debris also collects beneath it.
The sheet metal worker works directly with the roofer and the flat roof waterproofer and uses the same scaffolding. For facade work, facade installers and painters are also involved; for chimneys, the chimney sweep as well. Because responsibilities meet at the junctions, a joint site visit before work starts is worthwhile, so that everyone involved can agree the details on site.