Repairing roof covering? Choose the right scaffold.

Take the wide 135 cm version for roof covering, the RS52 from the Altrex range. That size looks heavy for a repair of less than a square metre, but you rarely go up with a sealant gun alone. Up with you go a length of roll material, a knife, a pressure roller, a bucket for the old stuff and usually someone to pass things across. On a slim deck all that ends up against your calves. On the wide deck you push it to one side and keep a walking strip along the edge clear.

What you cover from one position follows from the platform length of 245 cm. With a leak that matters more than usual, because the broken spot is seldom directly above the stain you can see on the ceiling indoors. You work along the upstand, along the vent pipe and along the joint with the dormer. With a good two metres of edge per position you walk a normal rear elevation in three or four moves, without skipping a suspect seam.

If the wide frames will not go through your gate, only the 75 cm version is left. You trade working room for access, and at ten metres up you feel that all day: every bucket you set down is in the way of something. Indoor towers such as the room scaffold or the one-person MiTower drop out for this job, because they come nowhere near this height. Go through the models standing ready for hire calmly before you commit to anything.

Do not aim at the ridge or the highest point of the building, but at the edge you have to step over. On a flat roof above the second or third storey that edge hangs six to ten metres above the garden. The reach that goes with it is what we call working height, and you work it out as your platform height plus roughly 2 metres that your arms add. That is where the 8 to 12 metres for this kind of roof comes from.

Ideally your deck stands a hand's breadth below the edge. Stay well under that and you hoist every roll above your head onto the roof without seeing where it lands. Come out above it and you step down onto the roof with a full bucket, which works even worse. So measure from the paving where the castors will stand to the top of the edge, and if you are in doubt pick the build that reaches a little further than you calculated.

Booking too low cannot be fixed afterwards. Nothing may be slid under the legs and nothing should be stacked on the deck to make up that half metre. So before you hire, check whether a rooflight, a chimney or a raised upstand rises above the edge that you also have to work on, because that lifts the whole job a rung higher. Which build goes with a reach of 10 metres is set out on the page about it.

Flat roofs often sit over an extension or a rear annexe, so the tower usually ends up in the back garden or on an inner courtyard. That is rarely the flattest part of the plot. Brick paving and a concrete drive are fine; a lawn that sinks under the castors after a week of rain is not. Clear a space of roughly three by three metres, because at this reach the four stabilisers stand well out and all four want to rest on the same firm layer.

Behind a house there is nearly always something in the way. Think of a water butt under the downpipe, a canopy sticking out half a metre, a shed hard against the boundary or a terrace with a step in front of it. Walk that route before the parts arrive, because every obstacle you have to work around means an extra move and so half a day of work. How to deal with a sloping garden is described in the notes on setting up on uneven ground.

Keep the supply line for your material in mind as well. A roll of roof covering is not something you get up a ladder on your own, so you want to stand close enough to the gate or the back door for things to be handed across. If the tower partly stands on the neighbours' path, mention it in advance. With a leak you often end up staying a day longer than expected, and that conversation is better had on a Monday than on a Wednesday morning.

Sealing takes an hour, finding takes the day. You start at the edge and the outlets, scoop leaf litter out of the corner by the drain, lift seams and sometimes pour water over a suspect strip to see where it goes. Before you know it the morning has gone. After that the spot has to be dry and clean before new material may go on. For most repairs that comes down to two to four days of hire.

There is waiting time in it too that you cannot speed up. A wet substrate does not rub dry, and a repair made onto damp will let go again sooner or later. The weather does the rest: in rain and in frost the roll simply stays on the ground and nothing happens. Plan tightly and have to be finished on day two, and after a wet night you stand with a half opened roof surface while the van is already at the door.

Happily the way the rate is built up works in your favour. Only the first twenty four hours are charged in full and every following day has 95 per cent taken off, so two days of slack costs you almost nothing extra. Set your end date not on the day you hope to be done, but on the day you know for certain it has worked. Every amount, VAT included, sits on the page listing the rental price per build, so you can do the sum before you book.

From one position you cover a good two metres of edge plus the piece of roof surface behind it that is still within arm's reach. Finish that section completely before you climb down: searching, sweeping, cutting out, laying new material and going back over the seam. Move halfway and you unpack and repack everything twice. With a leak you have not found yet the urge to shuffle along is strong, but then you lose track of which part you have already covered.

You move to the next position with an empty deck. Take off the roll, the knife and the bucket, even if you only shift two metres, and do not leave your coat over the guard rail either. Then look at where the castors will run, because a back garden is rarely laid true and a rocking slab gives you a crooked floor straight away. Tighten the four stabilisers properly again after every move before anyone climbs up.

Where it usually goes wrong is the logistics of the material. A roll of roof covering is heavy and stiff, and you would rather carry it once properly than three times badly. Take up only what you are certain you need per position and lay the rest ready beside the legs below, so that passing things up stays a matter of reaching. If you are also going through the repair of a leaking gutter, add a position and therefore a day.

What you get delivered is a complete set of loose parts, counted out. Agree in advance which square metres that stack may land on, preferably on the drive or right beside the gate and certainly not in the middle of the path you will be carrying a roll along. An order placed on a working day before 15:00 goes out for delivery on the next working day. With a roof that is already letting water through, that saves a night with buckets.

The date the parts arrive and the date they go back are yours to choose, and with roof work you set them against the forecast for the week you want to start. Ask for delivery a day before your first working day, then the build is behind you and you begin the next morning with full hours of daylight. Take the order of assembly from the step by step guide with you, so you are not puzzling over a brace halfway through.

Once the roof is watertight again we come and collect it all. You take the build apart, count the parts as you stack them and set them out complete on the same square metres where the van dropped them. If that count is right the job is finished as far as we are concerned and you have nothing else to arrange. What you pay for delivery differs by province and is listed with the rates for bringing and collecting.

The deck under your feet is rated for two hundred kilos per square metre, which is load class 3 under EN 1004. That sounds like a lot, but with two people, a full roll and a bucket of broken material you run up against it sooner than you expect. So spread the weight over the deck instead of putting everything in one corner against the rail. What you strip off the roof goes down before new stuff comes up.

The ordinary rules apply here too. Brakes on as soon as anyone gets on the ladder, nobody and nothing on the deck while you roll it along, and in a stiff wind you stay on the ground. You reach that limit along a free standing rear elevation at ten metres sooner than between two houses at four. Cut roof covering also acts like a sail that pulls at everything, so fix down what you loosen or throw it straight to the ground.

The real risk on this job is the step across onto the roof. As soon as you are over the edge you are no longer inside the rails and the scaffold no longer protects you. Only take that step if the work genuinely calls for it, keep the edge clear of tools and work from the deck as much as you can. Put nobody to work underneath the tower: a knife or a roll that goes down lands exactly there.