Replacing roof boarding? Choose the right scaffold.

Take the wide build of 135 cm here. With roof boarding everything turns on what fits on your deck and what you can park there for a while: a bundle of new lengths, a circular saw, a box of screws, a barrow load of old tiles still waiting to come down. On a slim deck there is nowhere to put such a stack without blocking your own walking route, and you notice that every time you pass. The wide platform gives you a working side and a storage side.

Something else plays a part: you are almost never up there alone on this job. One person works on the roof and the other passes things from the deck, and those two have to get past each other. On a floor of 75 cm you shuffle round one another all day, with a three metre board between you catching on something every time. The wide size is not a luxury here but a condition for working on without a fuss.

Only if the way through to the back really will not allow it do you fall back on the slim 75 cm variant, accepting that passing things across is slower and that you stack more often. Room scaffolds and the one person build stay out of the picture on a roof structure, since they are made for indoor and light work and come nowhere near this height. What is available and to what height you can look up among the mobile scaffolds standing ready to rent.

The governing point is the gutter or the bottom row of tiles, not the ridge. That is where you lay your material down, where you step across and where the stripping begins. On a house with a pitched roof above two full storeys that line hangs at six to ten metres. The height you order is the working height, and that figure is your platform height with about 2 metres of arm reach added on. For this job that puts you at 8 to 12 metres.

Set the deck a little under the gutter rather than above it. Stand too high and your knees are against the roof edge and you can pass nothing across without stooping. Stand half a metre too low and you lift every board up when you ought to be sliding it. Take your measurement from the ground the castors rest on up to the underside of the gutter, and bear in mind that a back garden often falls away by a decimetre or more.

A cramped choice punishes you for days on this work, because you do not shift material a few times but dozens of times. Every centimetre you have to bridge you pay back at the end of the week in tired arms and a slower pace. So before you hire, look as well at whether a dormer, a chimney or a projecting bay is in play that you have to work past or over. On the page about working on the second floor you see which heights are usual there.

The tower belongs close to the part of the roof where you begin, and that is usually the back or a side. Underneath you a heap of old material builds up, so reserve room for that too: a skip, a trailer or a fenced off corner for stripped timber and broken tiles. Make sure that dumping place does not sit directly under your working zone, because throwing things down while somebody is sorting below goes wrong eventually.

The ground has to hold this for days. A mobile scaffold that stands dead straight on the first morning can turn out, after three days of heavy carrying, to have sunk into a soft verge. Choose paving or a made up surface, lay boards or driving plates where you need to and check every morning that the four stabiliser legs still sit tight against the ground. A difference in level between garden and terrace you take up as described under stabilising and anchoring a build.

Add space for the delivery of new timber as well. Lengths of three or four metres have to go down somewhere without lying in the through route, and you would rather store them dry until the moment they go up. A sheet over a stack on the drive works better than standing everything against the wall. Think of the neighbours too: a roof that is opened up makes noise and dust for a week on end.

This is not an afternoon's work. Tiles off, battens loose, the old boarding out, the rafters checked, new material fitted, membrane and battens back and then every tile in its place again. For a single roof surface on a terraced house four to eight days of hire go on the calendar easily, and with an end of terrace or two surfaces it runs up further. On top of that count the day you lose putting the build up and taking it down.

Few jobs are as weather sensitive as this, because the moment the boarding is out your house stands open. So you work in blocks that you lay over a dry spell, and you sheet up as soon as showers appear on the radar. That sheeting and freeing it again the next morning costs you an hour each time, and that is exactly the hour nobody allows for. Cut it fine here and you spend a wet Wednesday wrestling with plastic.

For your hire period that means: take the longest option you still think reasonable. You set the start date and the end date yourself when you reserve, you may always hand back early and extending is usually possible too, so booking generously costs you little. Before you commit, look at how the models and heights relate to one another and how the rate runs over consecutive days, because that all sits together on the page with every hire rate.

Be plain about this. From the deck of 245 cm you work comfortably on the bottom metre of the roof surface: the gutter joint, the first row of battens, the fascia timber and the board that meets it. Everything above that you cannot reach from the platform, however high you set the build. For the middle section and the ridge you work on the roof itself, with the provisions that belong there. For that part the tower is your way up and your store, not your workplace.

That does not make the build any less valuable. With roof boarding it is precisely the carrying up and down that is the heavy part: a panel of two metres by one goes up from a deck easily and off a ladder not at all. You lay the new lengths ready on the platform, someone on the roof pulls them up, and the old material goes back the same way. Per position you finish a strip a good two metres wide before you roll the tower on.

Moving costs time, so plan it. Clear your deck first, because you may not roll with a stack of timber on it, and then set the legs out again. With roof boarding you move less often than on painting work, but with far more mess around you: screws, snapped battens and pieces of tile end up under your castors and then nothing rolls straight. If you are tackling the replacement of the gutter at the same time, allow an extra day.

You do not get an assembled tower but a collection of frames, decks, braces and legs that is counted before it goes into the van. Choose a square of ground in advance where that stack may lie and keep it clear of the skip and the new timber, otherwise you will be hunting for parts among the demolition material halfway through the week. With a job of a week it is also wise to have the delivery fall a day before the start.

If you have a van or a trailer of sufficient length yourself, you are welcome to collect the parts at no cost, by appointment, from Zeeburgerpad 89 in Amsterdam. For a build up to twelve metres that is a serious load, so count on several trips or have it brought. On a roof renovation most people choose delivery anyway, simply because you need your own van that whole week for timber, tiles and runs to the tip.

As soon as the last tile is back we take everything away again. You dismantle the build and stack the parts complete somewhere the van can reach; run through the count while you are at it. If it is all there, that side of the job is settled straight away and you have nothing to chase. Which provinces we drive to and what amount applies there is stated with the cost of bringing and collecting.

A deck in load class 3 to EN 1004 carries two hundred kilos per square metre. That sounds roomy until you work out that a bundle of sheet material, a tool box and two adults together go past it. With roof boarding that is a very real point, because you use the platform as intermediate storage. Lay heavy stacks against the uprights instead of in the middle of the deck, spread them along its length and take old material away before the new comes on.

The basic rules are not negotiable. Castors locked as soon as anyone goes up, no person and no load on the build while you roll it, and in a stiff wind you stay below. That last one counts double here: a loose sheet or a piece of membrane catches wind like an open door. Weight down anything light or take it with you at the end of the afternoon, so nothing can blow off the platform overnight.

The real danger on this job comes from above and from below. Above you work on a roof that is partly open, with rafters you may stand on and bays you certainly must not. Below, somebody is sorting old tiles. So fence off a zone around the foot, agree who throws down and when, and use a bucket or a chute for small pieces. More on this is set out under the rules for working at height.