Inspecting a chimney? Choose the right scaffold.

For looking at this height the RS52 at 135 cm wide is the pleasantest hire, even though you carry almost nothing up. You stand still for long stretches, rest a hip against the guardrail and hold a camera or phone in two hands; a narrow deck makes you fidgety doing that. There is also room for binoculars, a notebook and a mirror on a stick. The extra width also gives a tripod somewhere to stand. What else is in the range sits on the overview of mobile scaffolds available to hire.

Looking with two of you makes that width more welcome still. On this job one person points out what strikes him while the other photographs, and passing each other on a 245 cm deck should simply be possible without anybody hanging off the rail. That deck length also sets how far you can shuffle sideways to get a different angle on the stack without moving the whole build. Two metres across sometimes gives a completely different picture.

The narrow RS51 at 75 cm stays a perfectly good alternative when the only route to the right side of the house runs down an alley or through a gate. You trade away some elbow room, but your viewing angle does not change. A room scaffold such as the RS44 drops out here: it reaches 3 to 4 metres and is made for indoor work, and from there you see nothing of a stack at all. For roof work the numbers only start counting above the gutter.

When inspecting a chimney you do not measure to a point you must reach but to a point you want to see over. That is the gutter, and everything you hire above it gives you a flatter view onto the roof slope and so more sight of the base. For a two storey house that works out at a reach of 8 to 12 metres. Ridge stacks are the awkward ones to hire for. What such a build involves is on the page about ten metres of reach.

Take the platform height, allow roughly two metres of reach on top of it, and you have the working height, except that here you are not using those two metres to reach but to see over. If you want to judge the stack properly from above, your eyes belong level with the roof edge or just past it, and that alone is half a build. Start the tape on the paving under the wheels, and count in a drive that falls away or a garden path that has sunk.

Hiring too low wastes the day. With your head under the gutter you see the bottom course of tiles and nothing else, and of the stack only the upper half against the sky. You will have hired, built and struck without an answer to your question. For a house with the ridge above the second floor pick on the generous side. The frames for that last metre barely register; a wasted day certainly does. Measure once from the ground and once from the pavement, since the two rarely agree.

Find out first where the stack sits on the roof. On a mid terrace it often sits on the party wall and so close to one side; on a detached house it is regularly halfway along the ridge. The further from the roof edge, the more acute your view and the less of the lower courses you see. So put your build against the elevation nearest the chimney, even when that is the least convenient side of the house.

After that comes the ordinary question: can the build actually stand there. You want flat ground under the feet, and space all round for four stabilisers that at this reach swing out a fair way. A viewing spot that fits nowhere is not a viewing spot. On a side elevation watch the boundary, a shed or the neighbours' drive, because the good position sometimes sits just on somebody else's land. For a garden that is not level there is the guide to uneven ground under a tower.

Count on a complete picture costing two standing positions. From the front you see the front face of the stack and part of one flank; for the other flank you roll or rebuild round to the side. The back face often stays invisible, and that is not a shortcoming of your build but of where the chimney sits. Inspecting a chimney all round is worth planning before you fix a hire day, because a second position costs half a day rather than half an hour.

Looking costs little time. Once the build is standing you are done with the stack, the cowl and the lead in half an hour, photographs included. Putting it up costs more than inspecting a chimney does, and on this job that is the only thing that shapes your plan. For a single stack on an ordinary house one hire day is therefore often enough, provided you keep that day genuinely free for building, looking and striking. Do not assume you will fit an errand in as well.

Booking two days makes sense as soon as you want more than one face. Looking from two elevations means rebuilding in between, and that costs an extra half day. The weather counts too: with rain on the lens and grey light on the brickwork you simply do not see a hairline crack. A day with low sun tells you far more, and with a generous reservation you can wait for it calmly instead of forcing it. Sunshine straight on the brick flattens every shadow you were hoping to read.

That second day is financially mild. Day one carries the standard rate and everything you book behind it runs at ninety five per cent off, so a reserve day hardly shows in the rental price. What you do feel is a journey that has to be made again because you thought you had finished early and then wanted the other elevation after all. Reserve with a day in hand and return early if you like. Estimating such a short period is covered in the piece on the number of hire days.

Be honest about what inspecting a chimney from a hired build actually gives you. From a tower along the wall you see the face turned towards you, usually a fair part of both flanks, and the top edge if you stand high enough. What you do not see is the back, the lead on the roof side and the top of the cowl when it rises above your eye line. That comes with the job; it does not make your findings worthless, but it does make them incomplete.

So take out of it what is there. Zoom in with your phone rather than trying to get closer than the build allows, use a mirror on a stick to look behind the cowl, and shoot an overview and then a detail of each face. Write down what you see while you are still up top, because on the ground you no longer know which crack belonged to which angle. A second person watching from the street with binoculars often catches the bit you miss.

What you never do is step onto the tiles to see that last piece after all. A tiled roof is no walkway, you go through it or you slide off, and the tower you hire is meant as a working place at the edge and not as a step onto the slope. If it will not come out that way, the moment has arrived to have someone look who works with roof ladders and a harness. That is not weakness but the limit of what a mobile scaffold offers.

The parts arrive loose, counted and complete, and the stack needs a spot to lie for a while. A back garden delivery means every frame goes through the gate. On this job that is seldom a problem, since you usually build the whole thing the same morning and the pavement is clear again. Wrap the reservation up on a working day before three and the parts are with you the next working day. That way you can plan inspecting a chimney the moment you see something you do not trust.

You name the arrival date and the departure date yourself; on a short hire you would rather put those around a dry day. Two people and a clear morning is the honest minimum. Bear in mind that building at this height takes two people half a day, while the looking takes half an hour. So do not attempt it alone at the end of the afternoon. The order is set out step by step in the build plan for a mobile tower, with a video alongside.

Finished looking, you dismantle everything and put the parts together; the collecting is ours. Go through your photographs before you strike, because a forgotten corner otherwise means building again. Count the parts while you stack, and you will not be hunting a brace in the hedge afterwards. The parts go back exactly as they came, so a missing brace is easier to spot on your own stack than on ours. Transport carries a fixed amount per province, and that sits on the page about what bringing and fetching a set costs.

The floor takes 200 kg per square metre, load class 3 in the EN 1004 standard. On a visit like this you use a fraction of that, since it goes no further than a camera, binoculars and perhaps a tripod. That is not a free pass, though. The temptation is exactly to go up three at a time to look; keep it to two. What the class means is explained further in the note on that standard.

The risk when inspecting a chimney is not weight but posture. You stand still, you peer, and almost without noticing you lean out over the rail for a slightly better view. Do not: move the build a metre instead, even though that costs ten minutes. Brake the wheels before you climb, never roll it while somebody is up top, and reset the four stabilisers after every move before you go back up. That check returns at each viewing position.

Watch the wind as well, and what goes on below you. At twelve metres there is more wind than at street level, and a phone slipping out of your hand lands on the pavement where people walk. Use a wrist strap and stow loose things before you climb down. Beyond that the usual agreements from the rules on working at height apply, even for half an hour up there. Being up briefly makes the height no lower. A hired tower asks the same discipline for thirty minutes as it does for three days.