Installing screens? Choose the right scaffold.

For fabric on the upper storeys you hire the RS51, the Altrex RS TOWER 51 at 75 cm wide, a model carrying on to 14.2 metres of working height. On this job you stay far below that ceiling. The narrow base is a deliberate choice rather than an accident: the tower goes down afresh at every window, usually onto a pavement or into a front garden strip where a hedge leaves very little room to spare. Which versions stand ready is shown in the overview of the mobile scaffolds we hire out.

That width works well on the platform. You stand facing the reveal, the cassette lies lengthways along the guardrail and your tools sit at your feet. A screen cassette of two to three metres overhangs the deck at both ends, which is no obstacle at all so long as you keep it flat against the elevation instead of swinging it round. Everything else you need for installing screens fits into a single bucket hooked over the edge of the guardrail.

Where two of you lift a heavy cassette for a wide opening, the broad RS52 at 135 cm is worth weighing up. Two fitters stand side by side on that deck without getting in each other's way, and the headbox can be laid down flat while the brackets are being adjusted. The price of that is a tower harder to shuffle along an elevation and hungrier for pavement. On two or three ordinary windows it does not repay the extra carrying.

What you measure to on this job lies higher up the wall than most people assume. Forget the top of the glass and forget the top of the frame: aim at the upper edge of the brackets the headbox will finally hang from. Those brackets sit above the opening itself, inside the free space you surveyed before ordering anything. Then add half a metre again, because you want to stand square to a drill and to sight along the top of the box while setting it true.

Turn that measurement into a reach: platform height is what you climb to, and roughly two metres of arm and shoulder sits above it, and together they give the working height you book on. Fabric across an upper storey and the one below it therefore asks for six to eight metres, on a deck landing four to six metres above the pavement. State that range when you reserve, alongside the number of openings in the period. What such a build looks like is shown at an eight metre reach.

Setting the tower a stage too low punishes you the moment adjustment begins. With your eyes under the box you cannot tell whether it hangs level and you end up drilling by feel. You are also working with your arms above your head on a cassette you want to nudge a millimetre at a time. So pick the stage that puts the top of the headbox roughly at eye level. On a second floor window opening that choice saves half a working day when installing screens.

The position of your set-up follows the window rather than the other way round. The mobile scaffold therefore ends up centred on the reveal, with the deck at bracket height. That means a fresh pitch per window, and it means checking per window what lies underneath. At the front that is usually pavement or a tiled path; round the back it is a terrace, a planted border, or an outbuilding standing just that bit too close for comfort. Neither surface is a given until you have looked.

Look above all for what could put the frame out of true. A sloping drive, a sunken paving slab, a manhole cover or the grille over a basement light are the classics. All four adjustable legs have to rest on firm ground, because you will be drilling hard up there and that pushes the whole thing away from the wall. On soft or freshly dug ground, put boards down under each leg first. Taking up a difference in level neatly is covered in the advice for ground that is not flat.

Allow for the space you need in order to look, as well. A guide is not adjusted with your nose against it; you want to step back a few metres and judge whether the line is true. Where the tower ends up on a public footway, keep a route past it clear for pedestrians and check what is permitted in your street. At a bay or an extension, plan on two pitches for that one window instead of one, and count both of those moves into the hire day you booked.

Installing screens goes window by window, so it is the count of openings that matters and not the square metres of wall. Allow half a day per screen: take up the pitch, mark the brackets out, drill, hang the headbox, set the guides and run the fabric up and down a few times to watch it. Four screens on a front elevation therefore fill two full days, and that is before the motors are wired and before the morning spent building the tower. Count the moves between openings into the total as well.

The waiting comes from things outside your control. Fabric is cut to size for your openings, so the day it lands is the day that settles your start date. Beyond that you want dry and still weather: a wet reveal gives your plugs nothing to grip, and in any sort of breeze a three metre cassette refuses to sit quietly against the wall. Put your hire period after the screens themselves have been delivered rather than before, however tempting an earlier slot in the diary may look.

Booking wide is cheaper than starting again. That first 24 hour stretch takes the whole amount, and every later day is added at 95 per cent below it. Booking three days when you expect two therefore adds very little to the rental price, while it rescues the week if a motor refuses to run or a guide needs resetting from scratch. That saves a second delivery and a second build day. The rates per model and build are online including VAT.

You get 245 cm of deck length, and on this job that is rarely generous. A screen for a wide opening is often broader than the floor you stand on, so hang the headbox from a pitch taken mid-reveal and work outwards to both ends. Lay the cassette down lengthways before you lift it, never across the guardrail, where one end will always be in your way. When installing screens, set every bracket out first and hang the box into them afterwards in one movement rather than in stages.

Where the screw actually goes is the question that governs everything else on this job. Above a window opening there is usually a concrete or steel lintel, and that is sound ground. With external insulation in front of it you do not fix into the render but through the layer into the structure, using spacers so the box cannot pull back into soft material. On a timber-clad house you locate the backing behind the boarding, mark it out along the full width and only then reach for the drill.

Adjusting then happens in two directions. The headbox must hang level over its whole length, because a millimetre of difference shows up as fabric drifting to one side. The guides go up plumb and at exactly equal spacing, or the zip pulls crooked and wears itself out inside a single season. Let the fabric run all the way down and back up again several times while you watch it, and correct everything before you begin dismantling the hired mobile scaffold.

The mobile scaffold reaches you in parts, counted and bundled, and not in a built state. Before the van draws up, work out where that pile is allowed to go, because the pavement directly under the window is exactly the ground you need to keep free. A drive, a garage path or the grass strip beside a hedge suits far better. Order it on a weekday, with 15:00 as the deadline, and the next working day becomes your delivery day, so no morning goes to waiting in.

Arrival and departure dates are both yours to name at the moment of booking. For installing screens that mainly means talking to whoever supplies the fabric: only let the tower come once you are certain the cassettes have landed and been checked. Erecting it belongs to you. Work from the assembly booklet, watch the film once through beforehand, and at this height two people are finished inside an hour. See also how a tower goes up step by step.

After the final test run you take the set-up down and heap the parts together, and we collect them on the date you picked. Count the pieces as you dismantle and you will not be left short a brace at the end. Having your own transport and no wish to wait, you can load up by appointment at Zeeburgerpad 89 in Amsterdam, with nothing charged for it. What transport to your province costs is fixed in advance at the rates per province.

Load class 3 of EN 1004 is what every tower in the fleet is built to, and it carries 200 kg on each square metre of decking. On screen work you approach that sooner than you would guess: a three metre cassette runs to thirty kilos easily, and there are usually two fitters standing together. So share the weight out along the deck, and do not set the headbox down while two people are standing on the same board. The background is at what this standard actually governs.

The basic rules do not change. Brakes on before you climb, nobody and nothing aboard while you move it, and off you come in strong wind. That wind limit counts double here, because a three metre cassette behaves like a sail the moment you raise it. Never reposition the tower with the headbox still lying on the deck either: put it down at ground level first and send it back up only once the four legs stand firm.

The hazard belonging to this work comes from above your head. You drill at eye level or higher, so wear glasses and sweep grit off the deck before it turns slippery. Put the machine on a lanyard, because a drill that falls four metres cannot be stopped by anyone standing down below. Fence the area underneath off where people walk along that pavement, and leave the barrier standing for as long as the drill is running. More rules are set out at work at height in practice.