Replacing roof tiles? Choose the right scaffold.

For a whole course of roof tiles you hire the wide mobile scaffold, the Altrex RS TOWER 52 at 135 cm across. That width is not a luxury on this job. Every tile you lift out has to go somewhere before its replacement goes in, and that somewhere is the deck beside your feet. On a narrow platform you end up wedged between two stacks within the hour and cannot turn round. In the range of mobile scaffolds you can hire the RS52 is the model this work needs.

After the width comes the length of the deck, 245 cm. That is how much roof edge you serve from one position, and it decides how often you have to move before the whole slope is renewed. The slim RS51 at 75 cm goes through a side gate more easily, but on that deck you cannot keep old and new material apart. If the only route to the roof is a narrow passage, measure the opening before you book the wide tower. Under a metre and a half the wide build usually becomes too tight.

The difference with a repair job is the volume. For a broken tile or two you climb up with the replacement under your arm and are back down within the hour; a narrower build and a single hire day cover that. For a full course or an entire slope, hundreds of kilos travel over the roof edge in two directions. That is a different job, with a different model, more days and a working strip below that has to stay clear. Repairing single cracked roof tiles is covered separately.

When replacing roof tiles you measure not to the ridge but to the roof edge you work over. You stand alongside the slope and take the tiles across the gutter, so the gutter is your reference point. A house of two full storeys with a pitched roof puts you in the band of 8 to 12 metres. What a build to ten metres of working height needs in parts is listed on that page. If the roof of an extension sits in between, you still measure from ground level upwards.

Work back from that roof edge to the deck you will stand on. On top of your platform height comes roughly 2 metres of reach, because you take in a fair strip of slope over the guard rail. To work at ten metres, your top deck sits at around eight. Measure from the paving under the wheels and not from a raised terrace or a doorstep, particularly where the ground falls away towards the street. Half a metre of difference at the foot is half a metre short at the top.

Hiring too low shows up immediately on this job. With your chest under the gutter you lift every tile up instead of drawing it towards you, and with an armful of tiles you will not keep that going for half a day. You want the platform just under the roof edge so the material slides towards you. When in doubt take the taller build, because at hire that costs you less than a day of carrying at the wrong reach.

The wide tower goes as close to the gutter line as it can, and in most gardens that is precisely the strip with the most in the way. Think of a downpipe with a gully under it, a shed roof that oversails by half a metre, or a hedge grown hard against the brickwork. Clear that strip before delivery, because shuffling an erected tower loaded with tiles is not an option. Half a day of clearing pays for itself twice over when the build has to move four or five times.

The ground has to carry the build plus your material. Under every wheel belongs a flat, hard spot: paving, block setts or firmly trodden gravel. A lawn that sinks after rain is extra risky here, because you are stacking weight up top as well. The four stabilisers splay outwards and want room on each side, including the spot where your skip bag was going to stand. On sloping ground, read the notes on uneven ground before you begin.

Think about where the tiles you take off will end up. You want a fenced off spot beside the build below, a bulk bag or a skip, so you can unload in one movement. Do not put it directly under the platform, because nobody may stand there while you are working above. The pallet of new material goes on the other side. Together that is a working strip a few metres wide along the house, plus a path that stays clear for residents and neighbours.

Replacing a whole course along one elevation usually takes a day or two. For a complete slope you are quickly at four to five days, because you divide the work into positions along the wall and have to move the tower between them. Count the build day in, since on that first morning the scaffold is not standing yet. Carting the old material away and clearing the working strip take another half day at the very end.

The weather decides more than you would like. Tiles are slippery on a wet slope and on a frosty day you leave them alone; in strong wind the work stops anyway. Your hire period therefore has to be longer than the sum of your working hours. Look at the forecast for the whole week and set your collection date a day behind it, not on the date you would finish in the best case. Two dry days back to back are worth more here than four scattered ones.

Reserving with room to spare is inexpensive on a job like this. Only the opening 24 hours are charged at the full rate; each hire day that follows carries 95 per cent off it. A spare day in hand therefore costs almost nothing, while booking again with another delivery and another build costs both money and time. Let the collection date fall after the day the last section is closed. To judge that period for a large slope, see the guide to estimating hire days.

With a deck of 245 cm you serve a good two metres of roof edge per position. In practice you work upwards through the slope: you take out the bottom course, lay the new tiles in, and only then move along. That keeps the live work within arm's reach of the guard rail and saves you walking over the roof itself, which is unwise on old battens anyway. It also spares the battens under your knees a great deal.

Moving is the real time loss here. Before you roll the tower the deck has to be completely empty: no loose tiles, no tools, no bucket of hooks. Then the wheels go back on the brake and the four stabilisers come out again. Reckon on a quarter of an hour per move and add that to your planning. Anyone working along a ten metre elevation does that four times per lift and loses a good hour a day to it.

What people misjudge on this work is the weight that has to go up. New tiles arrive on a pallet and that pallet never goes up in one go. You take them in small stacks of five or six, or somebody passes them to you from the deck below. Always keep a clear route open on the platform between the ladder hatch and the spot where you are actually working, or you end up stepping over your own supply with a tile in both hands.

The mobile scaffold arrives as a complete, counted set of loose parts. The parts come out on the next working day when your reservation is in before 15:00, and you fix that date yourself. Plan the delivery for the day before your first roof day, so building it does not clash with the tile work. Let the pallet of new tiles follow after that, not before. The delivery charges per province are listed including VAT, so the figure can go straight into your budget.

Putting it up is your part of the job; a manual and an instruction video come with the set. Tackle it with two people, because the parts of a wide build to 12 metres are too unwieldy to work up on your own. Point out in advance where the parts may be laid down, and keep that away from the spot the pallet will occupy. A drive or a stretch of pavement works better than a border, because you have to walk round the parts while you assemble.

Afterwards we collect the tower again, on the date you picked at booking. You dismantle it and lay the parts out complete, somewhere the driver can reach with a sack truck. Count them through as you strip down, so that no brace, coupler or deck panel stays behind in the garden or behind the skip. Sweep grit and moss off the platforms as well; roof work always leaves a layer of it and that does not belong in the van.

Load class 3 within EN 1004 means that each square metre of decking may take 200 kg. That sounds generous, but on this job you reach it faster than on most: you, a second person and two stacks of material add up quickly. Spread that weight over the whole deck rather than piling it against the guard rail, and never have the contents of a full pallet up there at once. Two manageable stacks work better than one tall one.

The fixed rules weigh heavily here. The moment you step on, the wheels go on the brake, and you never move the tower with material or a person on it, not even that one metre. In strong wind you stop, because a slope stripped of tiles catches wind quite differently from a closed roof. After every move, check the stabilisers and the couplers before the first tile goes up, and see that the deck hatches are properly shut.

The hazard that belongs to this particular roof work is falling material. A tile that slides off the edge arrives below with real force, so keep the zone under the platform empty and fence it off if neighbours or children pass by. Do not work hanging over the rail; move the tower one extra time rather than reach half a metre too far for a tile. You will find the rest under the rules for working at height.