Removing a dormer? Choose the right scaffold.

For taking a dormer apart you hire the wide Altrex RS52, a mobile scaffold measuring 135 cm between the uprights. That extra width is no luxury on demolition work, because you are never standing still: you carry panels, lengths of frame and sheets of zinc across the deck to the edge and set them down for a moment before they go over. With two people side by side and a sawn out window between them, a slim deck is full straight away. All the models stand together in the mobile scaffold hire range.

The slim RS51 at 75 cm is usually too tight here. You can stand on it perfectly well to paint or to drive screws, but steering demolition parts between your feet gets awkward as soon as something of any size comes away. Count in that your tools lie there all day too: a reciprocating saw, a wrecking bar, a bucket for screws and nails, and a roll of sheeting for when the weather turns. At 135 cm you also keep a walkway clear, and that walkway is what keeps this work safe.

If a wide tower will not get round the back, that is the one real reason to rent slim after all. So before you book, measure the passage through to the spot where the dormer sits: a 90 cm gate, a path along the boundary, an alley between two houses. If the wide set will not fit, you carry the parts round in armfuls and build it there instead. The explanation of choosing a scaffold for a dormer puts the models next to each other.

On a dormer you do not measure up to the gutter but to the top of the dormer itself, because that is where the lead sits and that is where you start. On an ordinary two storey terraced house that point is soon 7 to 9 metres above the garden, and on a property with an extra floor it runs towards 11 metres. That is why you hire a working height of between 8 and 12 metres for this job and choose inside that band on the strength of your own measurement.

Those two figures are far apart, so measure before you book. What you state when you hire is the working height, and that already has roughly 2 metres of reach built into it: you stand on the deck and your arms come out above it. If you want your hip level with the roof edge you have to work backwards, since a deck at 7 metres amounts to a working height of about 9. What such a build looks like in practice is shown at ten metres of working height.

Renting too low punishes you immediately on demolition work. With the deck below the floor of the dormer, you lift every part you have freed before you can lower it, and that is exactly the movement in which people lose their back or their balance. You want the deck roughly level with the bottom rail of the dormer, so that everything comes towards you horizontally. Half a metre extra is one click at the booking stage; the wrong build costs you half a working day.

The tower goes directly under the dormer, and on most houses that means the pavement at the front or the terrace at the back. Look first at what lies under the four wheels: paving and tarmac are fine, a border or fresh turf sinks away the moment weight goes on it. Put spreader plates or thick slabs under the feet where you need to. The four stabilisers angle outwards and therefore reach further than the build itself is wide, so that spread belongs in your free space as well.

On this job a second object shares your pavement: the skip. You want it as close to the base as you can get it, but not so close that the stabilisers foul it or that you lose the way to the ladder hatch. Allow about a metre in between. If the skip has to stand in a parking bay, ask the council what that takes and arrange it in the same week that you book the tower, because those two applications rarely move at the same speed.

Then look at what stands between you and the elevation. An extension or conservatory under the dormer means you cannot bring the scaffold up to the wall and have to sit further back, which immediately costs you extra height. The same goes for a bay, a shed against the side wall or a low carport. If your terrace falls away or there is a threshold in it, read the guidance on uneven ground before the parts arrive.

The stripping out itself is a day's work with two of you and a timber dormer of normal size. But that day does not stand alone. Before it you lift tiles, tape up sheeting and seal the loft off against dust; after it the roof slope has to be closed, the battens have to line up and everything lying on the deck has to come down. In practice you therefore hire a mobile scaffold for three to four days, and no setback is priced into that yet.

The waiting sits in the weather and in the people who follow you. An open roof slope and a downpour do not go together, so you only start on the demolition on a day the forecast keeps dry into the evening. If a roofer or joiner comes behind you to close the hole, his diary partly decides how long the tower stays up. Plan your rental period around the day the roof has to be shut, not around the day you begin.

Booking generously is cheaper here than planning tight. Only the first 24 hours are charged at the full rate, and every day you hang on the back of that carries 95 per cent off. Two spare days therefore cost barely more than that first day alone, while they keep you out of the situation where the van is at the door and your roof slope is still open. Estimating a period like that is easier with the guidance on the number of rental days beside you.

A platform is 245 cm long and a dormer is often the same, or a shade wider. On a dormer of two and a half metres you stand in front of the whole front from one position; on a wide one of four metres or more you move the tower halfway through. Think that out first, because you want the second position on ground as level as the first. So measure the width of the dormer before you rent, and not once the scaffold is already up.

The order runs from light to heavy and from loose to load bearing. Glass out first, because you do not want it anywhere near you when things start being pulled; then the frames, the boarding on the cheeks and only last of all the roof structure. Everything that comes free travels down by way of the deck, in a bucket on a rope or hand to hand. Throwing is not an option: you never know who is walking under the tower.

What people misjudge is how much rubbish stays behind on the deck. Screws, offcuts of zinc, nails from the battens and sawn ends collect faster than you expect, and a mobile scaffold only rolls with an empty platform. So sweep before you move and lower the waste bucket first. A brush on the deck is not an extravagance on this job. If you are taking the replacement of the roof boarding on as well, allow a further round of planks over precisely the same route.

The tower arrives at your address as a complete, counted set of parts: uprights, decks, braces, guard rails and the four stabilisers. Orders that reach us before 15:00 on a working day go out the next working day. Point out beforehand where those parts may lie and take the skip into account while you do, because the skip claims the most useful piece of pavement. Put the set on the drive or in a corner of the garden rather than right in front of the door you use all week.

You choose yourself which day the scaffold comes and which day it goes again. For a dormer strip out it is best delivered two days before the demolition: one day to build and check it over, and a margin in case the drop lands in the afternoon. Anyone with a van of their own may collect the parts free of charge by appointment at the Zeeburgerpad in Amsterdam, though for a 12 metre set delivery is usually the sensible route.

Afterwards we come back for the tower; you leave it dismantled and stacked on the pavement. Wait with that until the roof slope really is closed and the last tile is down, because as long as anything remains to be done up there you want to keep your way up. Count the parts as you take it apart, so you know nothing has ended up in the skip. The charge for bringing and fetching in your region is set out in the overview of delivery costs by province.

The deck carries 200 kg for every square metre, which is load class 3 under the EN 1004 standard. On demolition you get near that sooner than on painting: two people together already weigh 160 kilos, and then a cut out frame has to lie there as well. So do not collect, lower each part the moment it is free, and use the platform as a hatch rather than as storage. What a deck like that may carry is worked out in the article on loading and weight.

The standing rules weigh heavily on this job. Put the wheels on the brake as soon as anyone goes up and never move the tower while someone is on it or while material is lying on it. Stop when the wind gets up, because a loose piece of roof boarding catches far more of it at ten metres than you notice on the ground. After every reposition, walk round the stabilisers, the braces and the guard rails, since on demolition you are knocking into them all day.

The biggest risk when you remove a dormer sits under the scaffold rather than on it. All sorts of things fall: screws, slivers of glass, a sawn off batten. Fence the zone under and beside the build off with tape or cones, certainly if the tower stands on a pavement children walk along. Wear a helmet even though it feels excessive, and agree that nobody stands under the deck while sawing or pulling is going on above.