Commercial Roof Removal and Replacement

A metal roof is due for replacement when rust has gone right through the sheet. Holes, flaking along the ribs, and rust around fixings and laps are the usual signs.

Other signs are sheets that have lifted or cracked, fixings that have worked loose or rusted away, and leaks that come back after they have been patched. On a large roof, water can travel a long way along the sheeting before it shows inside, so a wet patch on the ceiling is often some distance from the fault.

Plant, ducting and walkways add penetrations and foot traffic to a roof. The flashings around them are a common place for leaks to start.

The old sheeting, flashings and fixings are taken off. The purlins or battens underneath are checked, and any that are damaged are repaired or replaced. Insulation or sarking goes down, then the new sheets are fixed.

Flashings are fitted at the ridge, along walls and edges, and around every penetration such as vents, skylights and plant. Gutters, box gutters and downpipes are replaced where they have failed.

Yes. A metal roof is made of separate sheets fixed to purlins, so it can be taken off and replaced a section at a time. Each new section is lapped and flashed into the next until the whole roof is done.

Where the damage is limited to part of a roof, such as the run below a box gutter or the sheets around a plant platform, that part can be replaced on its own. The new sheets need to match the profile of the old ones so that the laps seal.

Many commercial roofs drain into box gutters that sit inside the line of the walls. When a box gutter rusts, blocks or overflows, the water goes into the building.

Box gutters are joined to the roof sheeting by flashings, so they are usually looked at whenever the roof above them is replaced.