Repairing a downpipe? Choose the right scaffold.

For a mend to a rainwater pipe the Altrex RS51 is the obvious choice: a slim 75 cm model whose lifts run from 4.2 metres of working height as far up as 14.2 metres. You will only use part of that range here, because you set it up around the point where the pipe is letting water out. The narrow footprint is the argument here, since a downpipe runs down a corner, past a shed or along an alley between two houses. The range of mobile towers on hire shows the alternatives.

The 135 cm wide version gives you more deck, but spot work on a pipe does not need it and you will not get that width down half the routes to the back of a house. A room scaffold is out because it is built for indoor work and will not reach a gutter. What is left is exactly what suits: a 75 cm tower you can carry through in armfuls of parts and that still stands upright on a path a metre wide.

The 245 cm platform mostly serves as a bench when you are repairing a downpipe. A replacement bracket, a roll of tape, a cartridge of sealant, a cordless drill and an offcut of pipe all sit side by side on it, and you still have room to move about. That matters here, because with a leak you never know in advance which tool will turn out to be the one you need. Climbing down for every item costs more time than the mend itself.

On this job you measure to the damage and not to the gutter. If the split sits just under the upstairs floor, or the wet trail starts at a socket on the first floor, a build of 6 to 8 metres gives you plenty. That figure is your deck height with roughly two metres of standing reach added on top. What such a stand asks for in parts is set out under a build of eight metres working height, worth a look before you book.

The awkward part is that water tells lies. The wet streak on the brickwork often begins well below the hole the water is escaping from, because it clings to the pipe before it touches the wall. So when you give us your height, allow your margin upwards rather than downwards. Stand too low and you end up staring at the underside of a socket, only spotting the hairline crack above it once the tower has already gone back on the van.

Measure from the slab your castors will actually rest on, not from the level of your back doorstep. Paving around a rainwater outlet nearly always falls towards the gully, so your starting point sits lower than you think. If the damage turns out to be higher than you first judged, an extra lift is easy to add when you reserve, but you cannot order a platform halfway through a hire day. Take the roomier stand: it barely moves the rental price and it saves your temper.

When you are repairing a downpipe you want the deck alongside the damage rather than square in front of it, because a pipe hanging under your nose cannot be inspected all the way round. Set the tower half a step to one side of the line of the run, so you can get at the socket and still have room to undo a bracket. Down below, allow a level area noticeably bigger than the tower, since the stabilisers splay outwards and want firm ground under them.

Traditionally there is more clutter round a rainwater pipe than anywhere else on the property. A water butt plumbed in with a diverter, an outside tap on a hose reel, wheelie bins, a cycle rack and a border planted right up to the brickwork. Clear all of that before the van arrives, not on the morning you intend to start. If the fault is above a single storey extension or a flat shed roof, look for a sideways approach, because this tower may not stand on a roof.

Watch the surface itself as well. Loose decorative setts and old slabs around a gully tip under a stabiliser foot and put the whole assembly out of plumb. A solid board under the foot usually settles it. How to take up a slope or an uneven bay is explained in the piece on uneven ground under a tower. Keep the gully cover clear too, so that when you test with water you can see where it goes and whether it drains away at all.

A single leak is rewarding work as far as time goes. Two of you will have the tower up in a couple of hours, finding and sealing the damage takes half a day, and dismantling goes quicker than building. That lands you on one working day, which is what most people book for this. If the fault is in a solvent welded joint, or a bracket has to go back into the pointing, all of that still fits inside the same day as long as your materials are ready.

There is one waiting period built in that you cannot shorten. Sealant and adhesive have to grab before you put water near them, and you would rather check that the next morning than half an hour later. Proving it is watertight also takes rain, or a hose run into the gutter. That is why a second hire day makes such a difference on this job: you inspect with the tower still standing rather than craning your neck from the paving.

That extra day hardly registers on the bill. You are charged in full for one day and one night, after which every further hire day drops by ninety five per cent. Book exactly one day, find the mend still weeping, and you are hiring again, arranging delivery again and building the whole tower again for ten minutes of work. Judging a longer job is easier with this guide to counting hire days in front of you.

The big difference from renewing a whole rainwater run is that you do not reposition. You build, climb up and finish the work from that one stand. Only if the damage runs over more than two metres, or you meet a second loose bracket on the way down, do you drop a platform. If the entire pipe has to come off, the character of the job changes and you are better off reading about renewing a complete rainwater downpipe.

Check your tools over before you step onto the ladder. An abrasive pad, degreaser, the new gaskets or collars, plugs in two sizes, the cordless drill and a small saw. Anything you forget costs a climb down and back, and that is a waste here because the mending itself is short. Put whatever can roll against the side of the deck where the guard rail is, because a length of pipe slides away faster than you would expect.

Cleaning first is the least glamorous part of repairing a downpipe and the part that decides it. A crack in zinc or plastic will not hold sealant over a film of green growth, and nine out of ten failures come apart on exactly that. While you are there, see whether the brackets above and below are still tight, because a pipe free to move splits again in the same place. Five minutes of checking from a hired scaffold saves you a second hire period later in the year.

Everything arrives loose and pre counted: uprights, braces, platforms, guard rails and castors, checked off one by one before it leaves us. Decide in advance where that pile is to land and keep the strip directly under the pipe empty, because you will be walking tools back and forth there. A driveway or a patch of grass beside the path works better than the path itself. Place the booking on a working day and beat three o'clock, and the parts are with you the following working day.

You pin the arrival date and the departure date yourself. With a weeping rainwater pipe you would rather have that arrival on a dry morning, so the build goes up dry and you can start straight afterwards. Erecting it is your side of the arrangement, and with a colleague, the printed manual open and the assembly film playing on a phone you are on the deck within a couple of hours at this height. Collecting the set yourself costs nothing and is arranged by appointment at Zeeburgerpad 89, Amsterdam.

As soon as the work is done we come for the parts again. You take the tower apart, count everything as you go and lay the full set out at the agreed spot. Before you start dismantling, have one more look at whether the mend stays dry under a good slug of water; from the platform you see that at a glance and from the ground you do not. Fixed charges per province are listed under delivery rates by region.

The deck you stand on belongs in load class 3 of EN 1004 and carries two hundred kilos per square metre. On a job like repairing a downpipe you will not come near that, because you go up with a bag of tools rather than a stack of materials. What does matter is the spread: put the cordless drill and the cartridge of sealant in the middle of the floor and not all against the rail you are leaning over as you work.

The ordinary agreements hold in full. Castor brakes go on before anyone sets foot on a rung, the deck is cleared of people and kit whenever the tower has to shift a metre sideways, and you stay off it in strong wind. That last one bites sooner here than you would expect, because you are often in a narrow passage between two houses where the wind pulls hard from one direction. The remaining rules sit at the rules for working at height.

The risks peculiar to this job are sharp metal and getting wet. Old zinc cuts when you open a split seam, so wear gloves. Water and green growth make the deck slippery the moment you flush a blocked pipe through, and you usually notice only as you turn round. Keep the zone beneath you clear, because a pulled off length of pipe or a falling bracket lands exactly on the slabs someone else walks over on the way past.