Fitting a sun blind? Choose the right scaffold.

A folding arm unit hangs above one window opening, which keeps the job neat: you are working inside a strip no more than three metres wide. The RS51 suits that exactly, the narrow Altrex version with a deck 75 centimetres across. That measurement threads past a bay, a downpipe or a parked car without you having to clear half the front garden first. Sizes and build stages for the whole fleet are listed with the mobile scaffolds in our hire range, including the heights you can order against.

The deck length of 245 centimetres covers the full width of the unit above an ordinary window. Both end supports are therefore within reach without climbing down in between, and the cassette can be laid into the brackets in one movement. That matters a great deal when fitting a sun blind, because the housing goes up as a whole and there is nowhere to rest it halfway. Work in a pair: one holds the cassette while the other runs the bolts into the brackets.

Where the plan is not one unit above one window but shade across an entire elevation, the approach changes completely; that story sits on the page about shading fitted across a whole facade. Here it stays one tower under one opening, and then the slim deck beats a wide floor you could not fill anyway. Fitting a sun blind above one window needs one position and no more. A wide unit over the garden doors at the back is a different job again, and that one is set out at installing an awning above a terrace.

The highest point of this job is the pair of brackets, and those always sit above the head of the frame. With that window on the first floor you land at 6 to 8 metres of working height. The sum behind it is simple: platform height with about 2 metres of reach standing on top of it gives the figure you order against. You want the fixing points at chest height, since drilling above your own head costs you exactly the accuracy the cassette will later hang on.

The unit sits higher on the wall than the drawing suggests. Above the head of the frame you still need room for the housing and for the pivots of the folding arms, and on top of that comes the mounting clearance the manufacturer prescribes. So measure from the pavement to the upper edge of those brackets and not to the top of the glass, or you will be half a metre short. What that stage looks like in practice is shown at an eight metre build.

Remember too that the fabric drops outwards rather than straight down. If you want to run the unit right out while the tower is still up, you need to be able to shift a little to one side. Where your window sits above an extension or a bay, take the measurement from that roof and not from the grass beside it. On a window at first floor level that can save a whole stage of build on the order. Half a metre of misjudged height is the usual mistake made here.

The position sits directly under the window the unit is going on, which on a front elevation means the pavement or half a parking bay. See whether you can free a strip of roughly two by three metres there, because the four stabilisers splay outwards from the base and every one of them has to find support. Leave a route past the wall for pedestrians, and if in doubt, ask your council what may stand in your street while the hire period runs. Fitting a sun blind over a public footway needs that check first.

Watch for the things that live under a window in particular. A sill with a projecting cill below it, a border, a gravel margin or the grating over a basement light all make the ground you want to stand on smaller than it looks. Where a drive falls away underneath, work the difference out on the spindles and check with a level that the deck really is flat before anyone climbs. A low box hedge is easier removed than worked around. Level ground under all four feet is not negotiable on this job.

Keep the swing of the fabric clear as well. A folding arm unit travels outwards and downwards on its first run, so you want no bicycle, planter or garden chair standing in that path. The cassette and its housing wait indoors by the door rather than out in the garden, since neither may get dirty or damp before it hangs on the wall. Getting the base solid is covered at steadying and tying a tower. Mark the swing path with tape if children use the garden.

Hiring a tower for one unit above a single window costs you two days in most cases. On the first you put the set-up together, mark the brackets out and drill the holes. Bolting the cassette in, adjusting the folding arms and running the fabric out happen the day after, which leaves room to correct anything that is not quite right. Anyone keeping to a tight schedule with two people occasionally finishes in one long day and hands the tower back later anyway.

Overruns nearly always come out of the wall. Land in a cavity where the plug finds nothing to bite on and you have to switch to a through fixing, which costs half a day of searching and trial. A unit made to measure can also turn up later than the supplier promised. So set the end of the hire a day beyond whenever you expect the sun blind to be hanging straight, rather than taking the tower down with the blind still crooked. Order the anchors for a cavity wall before you start drilling.

The way the tariff is built makes that extra day affordable. Day one is the one billed at the whole rate; after that a reduction of 95 per cent lands on every further date, so slack costs you next to nothing. That is welcome with a made to measure unit whose delivery date may still move. What the rental price comes to depends on model and height, listed at the rates per mobile scaffold, so you can see beforehand what a spare day adds. That extra day of hire is easier than a second visit.

Start by settling the projection, because that figure governs everything else. The projection is how far the fabric travels outwards, and you choose it so the hem still hangs above the pavement when the sun is low. Count back from the mounting height and keep enough clearance under the hem for somebody to pass without ducking. Check that against the wall before the first bracket is fixed, since correcting later means fresh holes and a row of old plugs to fill. Fitting a sun blind starts with that single number.

Then look at how the window itself opens. A casement or a top hung light that swings outwards fouls the fabric once it is run out, and that usually comes to light the first time somebody throws the window wide. Hang the unit higher in that case, or pick a projection that leaves the sash free. From a deck of 245 centimetres you take in the whole opening from one position and can try it calmly before anything is screwed down. Do that with the sash thrown wide.

The folding arms are under spring tension, and that is the sharpest part of fitting a sun blind. Leave the transport brackets on until the housing is bolted home, and keep your face out of the path of an arm. Then wind the unit slowly out for its first run and watch whether the fabric comes up evenly taut across the width. If a crease stays in it, adjust the arms while the tower is still under the window and you can reach them.

A counted set of loose components turns up on the day, dropped wherever you point. Do not have that pile placed directly under the window the sun blind is going on, because that is the ground you want to keep free. A garage, the side of the house or a corner of the drive works better. Confirm before the 15:00 deadline on any weekday and the set travels out on the very next working day, so you know exactly which morning to keep clear. Point that spot out before the van arrives.

Building it is your job, and a manual comes with the parts; a film online shows how the decks and the guard rails go in. Reckon on a pair of you spending a couple of hours on the build at this height. Put the delivery on the day before the unit itself is due to arrive, so the tower is ready and waiting rather than the other way about. The cost of that run out and back is listed province by province at the charges for delivery and collection.

Once the first run is behind you and the site is tidy we collect the lot again, on the date you fixed yourself. Take the tower down and stack the parts somewhere the driver can get to them, with nothing left in the hedge or behind the bin. Put that end date a day after your last fitting day and you keep time in hand to run the fabric out in sunshine and watch how it falls.

Everything in the hire fleet is built to EN 1004 in load class 3: the deck takes 200 kg for every square metre of its area. Fitting a sun blind does not take you near that ceiling, but do count what is up there at once: two people, a cassette of about three metres and a cordless drill with its case. Spread the weight across the deck boards. The standard and what it permits are unpacked at this note on the standard, with examples of what people take aloft.

The brakes go on before anybody takes the first rung, and the tower stays put as long as material is lying on the deck. Moving it with the cassette aboard is asking for trouble, even for one metre to the left. If the wind picks up, the fitting waits: an extended sheet behaves like canvas and pulls at everything it is fastened to. Up at deck height you feel a gust well before anyone notices it down in the street. Close the fabric and wait for a calmer morning.

The real danger on this job is the spring tension in the arms. One of them can fly open with force if the restraint comes off too early, so follow the order the manufacturer sets out and never stand with your head in front of it. Keep the zone under the tower empty while you drill, because dust and a falling plug land exactly where people walk past. The remainder is at the rules that apply at height. Warn anybody using that pavement while the drill is running.