Full re-roofs

Roofing and eaves sheeting installed before the late 1980s may contain asbestos. Corrugated fibre-cement roofing, the flat sheeting under eaves, and some old flues and vents are all common sources. It is not dangerous sitting still and undisturbed. It becomes dangerous the moment someone cuts, drills or breaks it, which is precisely what stripping a roof does.

On any building of that age the material needs to be identified before work starts, not discovered halfway through. Where it is present, removal is licensed work with its own controls and its own disposal requirements, and it has to be priced and scheduled as a separate stage. Anyone who offers to strip an old fibro roof without raising this is telling you something important about how they work.

This is one of the more common jobs and it is usually straightforward, because metal is dramatically lighter than tile. A tiled roof might carry fifty kilograms per square metre; a metal roof is closer to five. The structure almost never objects to losing that much weight.

What does change is the batten layout. Tile battens sit at spacings set by the tile, and metal sheeting has its own span requirements, so the battens generally come off and go back on at new centres. That is also the point at which the sarking and insulation go in, which is a large part of why a converted roof performs so much better than the tiled one it replaced rather than merely looking different.

One thing worth being clear-eyed about: the roof line changes. Tiles have a chunky, shadowed profile and metal is crisp and flat. On some period homes that reads as a significant improvement and on others it does not, and heritage overlays may have a view of their own.

The building is occupied and the weather does not care. Work is staged so only a manageable section is ever open, and each section is made weathertight before the crew leaves for the day. That is why re-roofs get rescheduled when a front is coming through, and why a contractor who is watching the forecast is doing you a favour rather than stalling.

It is also why the strip and the re-sheet happen in the same sequence rather than the whole roof coming off at once. It is slower on paper and considerably cheaper than a ceiling replacement.

Rotten or undersized battens, split rafters, previous repairs done badly, valleys that were never sized correctly, and framing that has been notched by another trade are all common finds. None of them are unusual and all of them are cheaper to fix while the roof is open than at any other point.

The way to handle that is to say so upfront. A quote that flags the likely finds as provisional items, with rates attached, is a quote you can trust. A quote that comes in low and clean and then arrives as a series of variations is not a better price, it is a worse conversation held later.