Scaffolding, towers and ladders: what your roof job actually needs

Two separate things. The first is the law. The Work at Height Regulations require the risk to be designed out where it reasonably can be, and a ladder is only accepted for work that is low risk and short duration — the figure the Health and Safety Executive works to is around thirty minutes in one position. Past that you need a working platform with a guardrail, because a man holding on with one hand is a man who will eventually not be holding on.

The second is the work itself. From a ladder you can reach roughly an arm's length either side, you can carry what fits in one hand, and you cannot put anything down. That is enough to hook a slate back in. It is not enough to strip a slope, set battens to a gauge, dress lead over a stack or lay a membrane, because all of those need both hands, a level surface and materials within reach.

So the question is never simply how high the roof is. It is how long someone will be up there, how close to an edge, and how much has to go up and come down with them.

Plenty of jobs are. A roofer who reaches for scaffold on every visit is either covering himself or adding a margin, and it is fair to ask why.

The ground, more often than the roof. A front elevation on a London terrace usually has nowhere to stand a ladder that is not a public footway, and a basement lightwell in front of the bay leaves no solid base at all. Sloping paving, soft borders and a patio over a void all fail the same test.

Weather stops it too. A slate roof is slippery wet and lethal frosted, and a ladder in gusting wind is a lever. Anything fragile underfoot — an old rooflight, a polycarbonate carport, a cement sheet garage roof — needs crawling boards and a platform regardless of height, because those roofs fail through rather than tip you off.

And working over glass changes it completely. A conservatory or a roof lantern below the work means a fall is a fall through glass, and the access has to be built so that nobody and nothing can land on it.

A mobile alloy tower is a proper working platform with a guardrail and a toe board, it goes up in about an hour, and it costs a fraction of scaffold. For a lot of London repairs it is exactly right: a chimney flashing on a two-storey rear, a rooflight reseal, a run of fascia and gutter, a small flat roof over a bay or a rear extension.

Its limits are real. It needs firm, level ground with room around it, so it is no use on a slope or a narrow side return. It reaches two to three storeys at the outside. It serves one bay at a time, so a long run means dismantling and rebuilding it along the wall. And it gives you a platform at the eaves, not edge protection on the roof itself — so it does not make a whole slope workable.

There is a point where nothing else will do, and a roofer who says otherwise is gambling with somebody's back.

Scaffold is priced by the scaffolder, not the roofer, and it is quoted as erect, hire for an initial period, then dismantle. The price moves a long way on the details underneath.

Scaffold standing on or overhanging a public footway or road needs a licence from the borough under the Highways Act. Southwark, Lambeth, Lewisham, Wandsworth, Merton, and Hammersmith and Fulham each run their own scheme with their own fee and their own turnaround, and it is days to a fortnight rather than an afternoon. The council will want a drawing and the scaffolder's public liability cover before it grants anything.

The footway has to stay usable, so a narrow pavement usually means a pedestrian gantry or a fenced walkway, plus reflective markers and lighting at night. In a controlled parking zone you will also need a bay suspension for the scaffold lorry and later for the skip, applied for separately and charged by the bay per day. A skip on the highway is a third permit again.

That lead time is why an emergency and a permanent repair are usually two visits. Nobody waits ten days for a licence with water coming in — the first visit is a make-safe from a ladder, and the proper repair happens when the access is legal and in place.

One more thing worth asking about: some home insurers want to be told when scaffold is up against the house, and some ask for a scaffold alarm on the ladder lift, because a scaffold is also a staircase to your first-floor windows.

If two prices for the same roof are a long way apart, the gap is very often the scaffold — one firm has priced it and the other has left it out, intending to raise it once the job is booked and you are committed. That conversation always happens on the morning the work is meant to start.

So make the access its own line and ask five questions of every quote. Is the scaffold in this price or extra. How many elevations does it cover. How long is the hire period included. Who applies for the pavement licence and the bay suspension, and are those fees in the figure. What does an extra week cost.

The other side of that is worth knowing too. Access is a fixed cost that does not care how much work you do while it is there. If the ridge needs re-bedding, the chimney needs repointing, the fascias are rotten and the gutters need replacing, doing all four on one scaffold costs far less than four visits with four lots of access. Send the whole list rather than the one thing that is leaking.

We tell you which of the three — ladder, tower or scaffold — your job needs at the survey, before you have spent anything, and it goes on the written quote as its own figure rather than disappearing into a rate.