Inspecting roofing? Choose the right scaffold.

For this inspection the RS52 is the model to pick: an Altrex tower with a floor 135 cm wide. Judging a roof covering, you often stand up there in twos, one leaning over the edge and pointing, one noting or photographing. On a narrow floor you swap places the whole time. On top of that you lean forwards over the upstand for this work, and then a deep floor with your feet planted well behind you is a good deal more comfortable.

The platform length of 245 cm sets how much roof edge you can go along per build. That is just enough to look at a run of seams and a stretch of bonded edge in one go, without moving halfway and losing the thread. Bring a moisture meter, a scraper and a torch and they lie beside you rather than in your coat pocket, which saves fiddling at height. What else stands ready is shown at the mobile scaffolds you can hire by the day.

If the flat section sits on an extension or garage only one storey high, the one person MiTower with a working height to 6.2 metres is enough and you work with fewer parts. For a dormer or a flat roof on the second storey it falls short. The slim RS51 at 75 cm stays the alternative when the way through to the back is tight, and the RS44 room scaffold you hire purely for indoor work at limited height.

Your highest measuring point on an inspection is the top of the upstand or the roof edge trim, because that is where the covering starts and where it most often goes wrong. For a flat section on the second storey that sits at 8 to 12 metres of working height. If it is the small flat roof of a dormer, measure up to that little roof rather than to the ridge of the main roof, or you hire more build than you actually use.

To get from height to build you use the usual relation: your platform stands about 2 metres of reach below the working height you state. On an inspection, though, it is not about reaching but about seeing, so look for the setting where your eyes come just above the roof edge. Stand too high and you look straight down on it and miss the blistering entirely. Which build belongs to that is set out on the page about 10 metres of working height.

Choose too tight and the assessment stops halfway. You see the surface but not the joint where the covering runs up against the wall, and that is precisely where water gets in. So measure from the spot your build will stand on, and remember that a terrace or a sunken garden puts your starting point lower than the pavement at the front. In doubt you hire the height above, because an assessment you cannot finish costs you the whole day.

Flat roof sections are rarely on the street side. Usually you are looking at an extension at the back, a bay beside the kitchen or a dormer to the rear, which makes your position the back garden or the path along the boundary. Walk that spot before you hire the mobile scaffold, because at many houses that is precisely where the obstacles sit: a shed, an outdoor air conditioning unit, a water butt or a raised terrace.

The ground has to be flat and carry the weight, including after a night of rain on it. Slabs and bricks are suitable, a lawn with a molehill in it is not. Around the foot you need room on all sides for the stabilisers, which stick outwards and must not end up half in a border. Half a metre of play all round is no luxury. For a sloping terrace or a settled path, see setting up on uneven ground.

Think about the route there as well. The parts have to go from the drop off point to the back, and a gate of 80 cm then decides more than the size of your garden. If a wide set will not pass, you would rather hire the slim version than lift everything over the fence. If part of your build ends up on the terrace next door, ask beforehand and not on the morning of your inspection.

An inspection is short work, and that makes this job different from most. You apply nothing, you have nothing to wait for and there is no drying time. For one flat section or a dormer you are usually through in a single day, building, looking, photographing and dismantling included. If you want to go along several sections, or the build has to move to the other side of the house, you hire it for a second day.

Even so that one day is tightly planned if you really only hire it for a day. The building takes half a day, and if it rains that morning you are looking at a wet covering on which cracks and loose seams are hard to see. Better then to book two days when you hire: the first to build and start, the second to finish calmly and take it apart without having to watch the clock all afternoon.

That costs less than you would think, because the full rate covers the first 24 hours alone, and a discount of 95 per cent applies to every day you add behind it. For a short job like this the second day effectively runs along free, while it gives you the room to go up once more when you have doubts about a photograph. See as well what stands in the piece on how long to keep a scaffold.

From the floor you go over roughly two and a half metres of the roof edge for each build, and you do that in a fixed order. Begin at the upstand against the wall, move on to the bonded edge and the trim along the rim, and only after that look out across the surface. Stroke a seam with a flat hand rather than pulling at it, because a seam still closed feels tight while one letting go gives under your fingers.

Blistering only shows when the light falls across the surface at an angle, so look low over the covering instead of straight down at it. Watch for pools left standing after a shower, for gravel that has blown away and for the point where a rainwater outlet is starting to silt up. Be honest about the limits of this workplace: from the tower you take in the roof edge and the first few metres, but the middle and the far corner stay out of sight.

Where this job often goes wrong is the difference from an ordinary roof survey. With inspecting the whole roof you look at tiles, lead, chimney and gutter, while here you judge only that one layer and sit far closer to your work. As a result you stand longer in the same place, move the tower less often and hire it for a shorter period, but per metre you look far more precisely than on a walk round the whole roof.

You get the mobile scaffold supplied in parts, counted and complete, and you put it together yourself. On a short job the planning therefore matters more than on a long one: book the delivery for the day before your inspection, so you are not waiting for the van while it happens to be dry outside. A booking that is complete before 15:00 on a working day lands on your pavement the next working day, ready to build.

The assembly is your part: with the manual and the accompanying video to hand, two people are busy for half a day. You decide yourself on which date the set is brought and on which date it goes away again, so you can put your inspection on the first dry day of the week. That is the biggest advantage of hiring by the day here: you tune the build to the forecast and not the other way round.

Afterwards you take the build down again and put all the parts together, after which we collect them. On an inspection that is quickly done, because nothing has got dirty and no material has been left behind. Go along the parts as you take them apart and you can be sure nothing has stayed lying among the plants. What the run out and back comes to is stated with the cost of delivery in your province.

According to EN 1004 this mobile scaffold belongs in load class 3, with a permissible floor load of 200 kg per square metre. On an inspection you come nowhere near that, because you carry only a phone, a lamp and some hand tools. It is exactly that light work which tempts people into sloppiness: they step on without braking the wheels because they will only be up there briefly. Do not, not even for that one photograph.

So brake the wheels the moment you step on, never move the build while anyone or anything is on it, and set the stabilisers properly again after every move. In hard wind an inspection does not go ahead, because you lean forwards over the edge on this work and you do not want a gust in your back. A day of postponement is rarely a problem, certainly not when you already fixed a second day at the hire.

The risk belonging to this job is over reaching. You want to see that seam two metres further along as well, and then your upper body goes over the guard rail. Move the tower along instead, one extra build. Nor should you step off onto the roof for a better view: on the scaffold you stand within rails, on a bitumen surface you are protected by nothing. What else applies is in the rules around working at height.