Metal Re-roofing

Older metal roofs are usually galvanised steel. The zinc coating wears away over the years, and when it has gone the steel underneath starts to rust. Rust starts where water sits: at laps, around fixings, under leaves and along the bottom edge of each sheet.

Paint on an old roof fades and chalks, and it can hide rust underneath. Fixings loosen as the roof expands and contracts in the sun, and the washers under them perish.

Holes or flaking in the sheet mean the rust has gone right through. Sheets that lift or rattle in wind have lost their fixings. Laps can rust together or open up, and water gets in at the join.

When these faults are spread across the roof, the sheeting is usually replaced as a whole. When they are limited to a few sheets, those sheets can be replaced on their own.

Metal roof sheeting comes in corrugated and square-rib profiles and in a range of colours. A full re-roof can change the profile or the colour. A partial replacement needs sheets of the same profile as the existing roof so that the laps seal.

Yes. A metal roof is made of separate sheets, so it can be removed and replaced in sections. Each new section is lapped and flashed into the next.

A metal roof is held down by screws through the sheet into the purlins or battens, with a sealing washer under each head. Ridge capping covers the join along the top of the roof, and barge capping closes the gable ends.

Flashings seal the edges of the roof and the joins against walls, chimneys and skylights. On an old roof these parts have usually aged with the sheeting, so they are renewed along with it.