Installing cavity wall insulation? Choose the right scaffold.

For filling a cavity in a two storey house you take the 75 cm Altrex RS51, and the narrow base is a deliberate choice here. The strip along the wall is already carrying the hose, the plant and often a path through to the back garden, and a wide undercarriage swallows every bit of that. Widths and builds are gathered together on the page of towers you can hire by the day, the narrow model set out beside the wide one for comparison.

Little kit goes up with you in the first place: the lance hangs from the hose, a cloth and a stopper live in your pocket, and the sacks stay down beside the plant. Beads or fibre travel up through the hose rather than in your arms, so the deck stays clear for your feet. The wider 135 cm RS52 only earns its place when two of you work aloft together, one on the lance and one capping behind, and both need room to pass.

The dimension that shapes how the day runs is the 245 cm deck, since it fixes how many openings one stand serves before you roll along. A broad deck buys working room rather than reach. The single-person MiTower stops at 6.2 metres and belongs on a bungalow or a garage wall, never on a two storey job of this kind. Compare the two facade builds properly in the overview of tower sizes before any dates are committed to, because a change of model later means a change of build.

The uppermost openings sit immediately beneath the roof edge, because a cavity has to come full right to the top course. Measure to that final row rather than to the gutter, and two storeys returns a working height of 6 to 8 metres. Turn the figure into a build by adding what you reach while standing, near enough two metres, to the height of the platform itself. Which assembly matches that band is worked out in full at a build reaching eight metres, part list included.

Something else counts on this job. You fill upwards, so from each stand you want two or three rows of openings within reach: the row at chest height, the row beneath it and the row just above your shoulders. Pick the build so one deck covers a broad band of elevation rather than pinning it tightly to the highest hole. That saves stripping an intermediate platform out and resetting the whole thing halfway through the afternoon, with a charged hose lying across the deck.

Your tape begins at wheel level, since a back garden seldom sits flush with the pavement out front. Come up short and the top row stays unfilled, leaving a cold strip directly under the roof where heat escapes quickest. Putting that right later means hiring a tower once more and building the whole thing a second time before installing cavity wall insulation in a single missed panel. Where the wall runs on past the windows of the first floor, take the roomier build without arguing about it.

Ground beside the tower is doubly occupied on this job. The plant stands there with its sacks alongside it, and the four stabilisers reach into precisely the same area. Put the machine next to the stand rather than under it, so rolling along does not begin with shifting a loaded hopper across the path. What you want is level ground running wider than the stand on all sides, with room to slit sacks open and somewhere sensible for empty packaging to end up.

Decide exactly where you will stand before the parts are dropped off. Slabs, a drive or a raked path will do; grass that gives way under four wheels after a wet week certainly will not. Watch the run of the hose too, since it climbs from the plant and must not finish under a wheel or chafe across the sharp edge of a sole plate. For a step between terrace and garden, ground that slopes away offers practical answers.

Think about the neighbours, and think about dust. Some material always escapes around the openings while you are filling, and it carries a good deal further than people expect it to. Cover a pond, a vegetable patch or an open cellar light before you start, and avoid setting up right beside a car that has to stay parked all day. The tower is tied to nothing whatever, since nobody drills anchors into a cavity minutes after installing cavity wall insulation behind it.

The filling itself finishes surprisingly fast. An ordinary two storey terrace is done inside a day, assuming the pattern is set out already and the cavity behind the brickwork holds no surprises. That tempts people into booking one single day, and that is exactly where it goes wrong. Time goes into everything around the filling: capping openings with mortar that matches, brushing the brickwork down, and only then checking whether the result actually holds up across the whole elevation you have filled.

Meet an obstruction and the whole plan slides. Rubble at the bottom of the cavity, mortar snots on the wall ties or a pipe blocking the flow all mean extra holes and a second attempt at another height. You discover it mid job, because the machine either empties faster than expected at that spot or refuses to feed at all. Carry a day of slack in the period you hire, even in cases where the survey beforehand was done as thoroughly as anyone could ask.

Your wallet copes with that easily enough. Full rate applies across the opening twenty four hours, while every day placed behind it counts with 95 per cent removed, so the slack weighs almost nothing. What does matter is this: send the tower away too early and there is nothing left to stand on when the thermal camera finds a cold patch. Every model has its own rental price, and every one of them is gathered at the rates for each tower alongside the builds they belong to.

Each stand handles a band of wall as wide as the deck, so 245 cm of brickwork. Inside that band you work from the bottom row upwards, opening by opening, so the material settles on itself and leaves no voids behind. Only once the band is full over its whole height do you roll along to the next one. Work across an elevation at random and you lose track of what has been filled, which surfaces later in the thermal images as a patchwork rather than an evenly insulated wall.

Blowback is your chief instrument while installing cavity wall insulation. When material shows at the neighbouring opening the panel is full and you stop; when it never shows, something is in the way or the material is escaping somewhere else entirely. That is why both holes want to be in view from the deck without craning around an upright. Cap each filled opening at once with a plug, or the contents run straight back out while you charge the hole beside it.

Capping belongs inside the same hire period. You close the openings with mortar matched to the colour and grain of the existing pointing, and that only works while you can still reach them from the deck. Do the round from the same stand, directly after the band is full, and no metre of wall has to be reached twice. How the pattern you are working through came about, hole by hole, sits on the sister page about judging the cavity first, which is where the survey work is described.

The tower reaches you in loose pieces, as a set counted through in advance. Agree beforehand where those pieces are to land, because the strip beside the wall is already promised to the plant and to the stock of sacks. A drive or a corner of the lawn beats the path along which you will be laying the hose. Place the order during working hours and finish it before 15:00, and every part of it turns up on the working day that follows.

Arrival day and departure day are both recorded when you hire. On this job let the set come the day before the filling: assembly is yours, a couple of hours with two people, the sequence set out by the manual and the video. Plant pulling up at eight while you are still levelling frames costs half a session of waiting about before installing cavity wall insulation even begins. The step by step assembly guide shows exactly what goes where and in what order.

Collection we arrange; dismantling stays yours, and the order matters a great deal here. Take nothing down before the mortar is in the openings and the elevation has been read over, or you lose the chance to fill a forgotten panel. Stack the whole set complete where the van reaches it easily, so not behind a gate that has to be locked. What your region charges for the round trip out and back is at delivery charges listed by region, so it can go into the plan early.

Load class 3 applies to the towers in this fleet, an EN 1004 rating that puts 200 kg on each square metre of deck. You and the lance stay well inside it, but a hose full of material weighs more than it looks and tugs steadily at your arm besides. Set the brakes before hauling that hose upwards, and lay it across the guardrail in a generous curve rather than pulled tight down an upright where it will snag on a brace.

Rolling happens with an empty deck and a hose pulled clear first, never with anybody aboard. Take the hose along in the direction of travel, drop all four stabilisers firmly afterwards, and check nothing is trapped before the plant starts again. That check costs half a minute and saves a pinched line. In strong wind you stop altogether: escaping material blows across the entire garden next door as well, and you stand unsheltered on the topmost deck while it happens.

The hazard that genuinely belongs to this job is dust and a slippery deck. Material coming back out of an opening spreads across the platform, turns greasy underfoot and gets into your eyes whenever you look upwards. Sweep between bands, wear goggles, and keep the area beneath the tower clear of people, since a lance breaking loose whips about hard. The remaining rules, including what to do when the wind turns, sit at the regulations covering work at height.