Replacing lead flashing? Choose the right scaffold.

At this height you go for the RS52, the wide version at 135 cm. Two reasons settle it. First you are standing high, and a broader base stands noticeably calmer at eight to twelve metres than a narrow one. Second you carry material up that has weight to it: a roll of lead half a metre wide weighs more than a tin of paint, and that roll needs somewhere to lie clear of your feet. What else stands in the hire range of mobile scaffolds is rarely a better answer for this job.

The deck that is 245 cm long and 135 cm deep gives you exactly what you need: your roll, your dresser, your mallet and the sealant gun on one side, room to kneel and dress on the other. On lead work you are often working low over your deck rather than upright, and then a narrow version is cramped. Two people on the same build, which is quite normal on this job, also fit here without stepping over one another or shifting tools about.

You only fall back on the narrow 75 cm RS51 when the way through to the facade really leaves no room. You give something up for it: less deck to put your material on, and a build you have to level even more carefully at this height. Where you have the choice, take the wide version and accept carrying a few more parts round the back. How high you may go with either model is at the maximum height of a mobile scaffold.

The point you have to reach is the joint itself: the bottom row of lead flashing along the chimney, the bead along the cheek of a dormer or the strip where the lead is let into the wall. On a house of two to three storeys that lies at eight to twelve metres, counted from the street where your wheels end up. Sits the joint at second floor level, then you are at the top of that range and you build on well past the gutter.

Translate that measurement into a build next. Your platform ends up at six to ten metres, and your arms add about 2 metres on top of that before you touch the joint. For lead work you would rather stand slightly lower than the maximum you can get to, with the joint somewhere at chest height. If the work is over your head you cannot put force behind it and you will never press the flashing tight into the joint.

There is a second measurement that counts and is often forgotten: the horizontal distance. A chimney standing two metres back from the roof edge you can no longer reach from a build against the facade, however high you go. So measure not only upwards but backwards as well before you commit to anything, because that decides whether this work can be done from a scaffold at all. Which build belongs to this reach you see at twelve metres of working height.

The standing place follows from the line you have to reach. Find the point on the ground directly under the joint first, and then look at whether there is space there for a build 135 cm wide plus the swing of the stabilisers. With a chimney near the ridge that often means you end up in the front garden or on the pavement. If that point lies above an extension, a conservatory or a garage, a build at ground level drops out and you have to look for another solution.

At this height the ground matters more than on a low job. A deviation of a centimetre down below becomes a hand's breadth up top, so level the build carefully and use all four stabilisers as this height requires. Do not set them half out because a paved path is just too narrow; move the whole build a metre instead, even if that costs you half an hour. Stabilising and anchoring says what else is needed as the height climbs.

Finally think about the zone under you. The old lead you strip out comes down, and so do bits of mortar, pointing and sometimes a tile that works loose. Cordon that zone off, certainly where the build stands on a pavement or a drive people want to pass along. With lead flashing round a chimney more loose material falls than you reckon on in advance, so put a sheet down and talk to the neighbours about where their car goes during those days.

The number of square metres is small, but the operations go slowly. Getting the old lead out, raking or cutting the joint, snipping new lead to size, dressing it until it follows the shape of the tiles, working it in and finishing off with sealant or mortar: per side of a chimney you are half a day gone before you know it. For a chimney you tackle all round, or a dormer with two cheeks, that soon runs to two or three days of work.

The build time comes on top of that. A ten metre build does not go up in an hour, certainly not if you still have to move it halfway to the other side of the chimney. Count that build day separately and do not count it as a day on which you get to the lead. Bear the weather in mind as well, because on wet tiles and with wind at ten metres you do not do this work. A spare day is therefore not a luxury here but simply part of your planning.

Luckily that extra day weighs little. The opening 24 hours are billed at the full rate and every day that follows has 95% taken off, which keeps the rental price of a roomy period close to that of a tight one. Ordering again after a break, by contrast, costs you a whole first day once more plus two extra runs of the van to your address. Making a realistic estimate works with the rules of thumb for rental days beside you.

Finish the joint side by side and not piece by piece. Stand on your deck, do the whole line you can reach from that stand, and only move once that side is done and watertight. With 245 cm of deck length you usually take a complete dormer cheek or half a chimney side in one go. A transition between two stands you never put in the middle of a joint, but on a corner or exactly where the pieces of flashing overlap generously anyway.

Make sure you have everything up before you start. Lead cut to size, a pair of grips, the dresser, a wooden mallet, sealant, a cloth and a bucket for the old material: every trip down costs you a few minutes at this height that you never win back. Pull the roll up on a line along the outside; climbing the ladder with it under your arm is asking for trouble. Lower the old lead the same way and do not throw it down, because it is heavy and bounces everywhere.

Bear in mind that from a build against the facade you cannot reach everything. The side of the chimney facing away from you is out of range, and that means moving or even a second build on the other side of the house. Take that into your planning, because such a move costs half a day. If you take the repair of other lead work with you, plan it in the same period, since you are up there anyway.

At this working height you get a fair number of parts delivered: uprights, braces, several decks, guardrails and the stabilisers, all counted and complete. It is clearly more material than for a low build, so genuinely set a place aside for it. A drive or a corner of the front garden suits better than a narrow path along the house, because you want to lay the parts out in order before you start stacking. That saves a lot of searching while you build.

Place your order midweek and make 15:00, and the delivery falls on the working day after. The arrival date and the date everything goes away again you fill in yourself, and with lead work you would rather put that first date just before a run of dry days. Building up is your own job, and at this height not on your own: bring somebody with you, keep the manual within reach and set the video beside it on your phone.

Once the joints are finished you take the tower apart and stack the parts somewhere clear; we come to collect them on the day you gave us. Breaking down goes from the top downwards and at ten metres takes more time than the build suggests, so do not start it at five in the afternoon. The amount for the run in your province you can check under the costs of delivery, neatly including VAT and fixed in advance.

Load class 3 from EN 1004 puts the limit at 200 kg per square metre of deck. On lead work you come closer to that than on most jobs, because a roll of lead, a bucket of broken-out material, tools and two people add up fast. So spread the weight along the length of your platform instead of piling it in one corner, and lower the bucket as soon as it fills. What that class means is at loading and weight.

The standing rules weigh heavier up here than down below. Set the brakes first and only then climb on, let nobody and nothing stay aboard while you roll, and come down as soon as wind gets up. At ten metres you feel a gust you would hardly notice at three, and with a sheet of lead in your hands you are also holding something that can catch like a sail. In that case rather wait a day than try it anyway.

Watch as well for the temptation to step over the guardrail onto the roof plane. Tiles are slippery, certainly with a bit of moss or damp on them, and a build is no stepping stone onto a roof unless you arrange something extra for that. Stay on your deck and move once more rather than stretching for the last piece of flashing. The rest of the agreements are at what is expected of you at height.