Metal Sheet Roofing
Sheet metal roofing covers flat and shallow-pitched roofs, valleys, gutters, flashings, domes, spires and turrets. Lead is the traditional material and remains the standard for repair on historic buildings; copper and zinc appear on nineteenth and twentieth-century work and on new interventions. The failures are predictable and mostly avoidable: bays sized too large so thermal movement splits the sheet, insufficient falls, inadequate ventilation beneath the deck causing underside condensation, and incompatible metals in contact. The contractors in this category work to the established codes for each material.
What this category covers
- Lead sheet roofing, gutters, flashings and weatherings
- Copper and zinc roofing and detailing
- Domes, spires, turrets and complex geometry in sheet metal
- Ventilated and warm deck construction beneath sheet roofs
- Repair of split, fatigued and creeping historic leadwork
Getting sheet metal roofing right
Size the bays correctly. Most lead failures are thermal fatigue caused by bays that are too large or sheet that is too thin for the location, and they show as splits along fixed edges. The published codes give bay sizes and thicknesses for each application; they are worth checking against a quotation.
Ventilate underneath. Condensation on the underside of sheet metal roofs corrodes the metal and rots the deck, and it is invisible until the ceiling below is stained. Ventilated construction, or a properly designed warm deck, has to be part of the specification.
Keep falls generous. Standing water on flat lead and zinc accelerates corrosion and finds every imperfect joint. Falls should be designed rather than inherited from an existing deck that never worked.
Watch metal compatibility and run-off. Copper run-off onto zinc or aluminium causes rapid corrosion, and different metals in contact behave in the same way. Where materials are mixed on a historic roof, the drainage sequence matters as much as the detailing.
Questions to ask
Why has my lead roof split?
Almost always thermal fatigue: the bay is too large or the sheet too thin, so repeated expansion and contraction against fixed edges works the metal until it cracks. Patching a split without resizing the bays usually leads to the same failure again.
Is lead still the right material for a historic roof?
For repair and replacement on historic buildings it generally is, because it is the original material, it is durable and it can be dressed to complex shapes. Copper and zinc are appropriate where they are the original material or on new work.
Why does condensation form under a metal roof?
Because the metal is cold and moisture from below reaches the underside of the sheet. Without ventilated construction or a correctly designed warm deck, that moisture condenses, corroding the metal and decaying the deck out of sight.
The business listed under Metal Sheet Roofing
- C.E.L. Ltd Cambridgeshire
Directory information is provided to help visitors identify potentially relevant specialists and suppliers. Inclusion does not constitute a recommendation, approval or guarantee by Tuscan Foundry Products. Please check current services, credentials, availability and suitability directly with each business.