The working at height hierarchy of control, with real site examples

What the hierarchy really means on a live job

You hear people talk about the working at height hierarchy, then you get to site on a wet Tuesday and someone is already unloading a ladder. The hierarchy is not a slogan. It is a way to make decisions the same way, every time, so people go home in one piece. The Work at Height Regulations 2005 reg 6 sets it out as avoid, prevent, mitigate. That is the order. If you ignore the order, you end up relying on luck and a harness, which is exactly what the law wants you to avoid.

Think of it as three doors. Door one, you avoid the height. Door two, you work at height but you stop people falling with collective protection. Door three, you accept a fall might still happen and you reduce the harm. If you find yourself opening door three at nine in the morning, you should be able to point to the reasons why doors one and two were not possible, not just that the scaffold would have been a faff or the MEWP was booked elsewhere.

We see crews with good habits do the same simple thing first. They ask if the job can be brought down to them. If it cannot, they look for guardrails, platforms and a sensible access choice, and only then think about nets, airbags or a harness. The smell of cut cement board, the wind pushing spindrift off the roof, the broken gully below, all of that matters. The hierarchy helps you strip the noise back to what will actually stop a fall.

Step 1: avoid the height in the first place

Avoiding the height sounds obvious, but it is the step most often skipped. Can you prefabricate fittings at ground level, then lift them in as a unit? Brackets for a duct run, a run of cable tray, a bank of solar rails, they can often be set up on trestles by the van, checked, labelled and lifted in. On cladding jobs, pre-cutting and colour-marking panels on the deck stops people measuring with a tape on a live edge.

Long‑reach tools help more than people think. Clearing gutters with a vacuum pole saves a set of ladders on a greasy patio. Testing smoke vents from the panel avoids opening roof hatches. Even moving a CCTV camera using a mast with a tilt base stops a cherry pick. The job feels slower at ground level until you add in every climb, every reposition, every chance to slip on a rung with wet boots.

Design out the height if you can influence the spec. Choose hinged or sliding plant screens, not fixed panels that need someone leaning out. Put isolators on the ground floor where possible. On small commercial sites, plan crane lifts to land kit where it will be worked on, not just where the lorry can park. If the client wants it quicker, remind them the law, the Work at Height Regulations 2005, asks you to avoid work at height where it is reasonably practicable.

For a deeper look at planning, inspections and documents, see our work at height RAMS guide which turns the legal duties into what you brief on site.

Step 2: prevent the fall with collective protection

If you cannot avoid it, your next job is to stop anyone falling. Collective protection comes first because it protects everyone without them having to do anything clever. That means fixed scaffold with guardrails, a properly built mobile scaffold tower, a platform on a MEWP, or a permanent working platform with edge protection. Handrails, toe boards, fully boarded platforms, sensible step‑offs and no gaps. This is the bread and butter of preventing falls under the Work at Height Regulations 2005.

Scaffold vs MEWP vs ladder is a choice you make with the job, not with habit. For a two‑week facade repair over a pavement, independent scaffold with fans and a pavement licence is usually the right call. For a day of louvre cleaning around a plant deck with decent access roads, a boom MEWP is often quicker and keeps edges behind mid‑rails. For a five‑minute adjustment at 3 metres, a properly footed ladder can be fine, but only if the task is low risk and short duration. If a ladder stays up all morning, it is not short duration.

Ground and surrounds decide a lot. MEWPs hate soft verges, voids and utility covers. You cannot magic bearing capacity onto paving laid on sand. Scaffold needs ties or buttressing and somewhere to land boards and tubes without blocking fire exits. Towers need level ground and someone who actually holds the PASMA card and knows 3T or AGR methods, checked against current NASC guidance. Ladders need a flat base, secure top, the angle right and someone to say no when it is windy.

Duration and repeats matter. If you have to go up and down fifty times, choose a platform with guardrails and step‑off points, not a ladder. If you will be carrying kit, think how you will handle it without leaning out. If you need both hands all the time, a ladder is probably the wrong tool. If the work face moves along twenty metres, scaffold or a tracked boom that can slew and travel at height will save you risking a reposition every two minutes.

Step 3: mitigate the consequences if a fall still happens

Mitigation accepts that even with prevention there is still a risk. You reduce the harm if someone does fall. Safety nets beneath a roof steel, airbag systems on a deck, soft landing systems, or personal fall protection. Nets and airbags are collective, so they sit above personal kit in the hierarchy because they protect everyone on that area, not just the person wearing a harness.

Personal protection splits into work restraint and fall arrest. Work restraint stops you reaching the edge in the first place, like a fixed‑length lanyard clipped to a certified anchor so you cannot get into a fall position. Fall arrest is the last resort because it lets you fall, then stops you, which means forces on the body, swing, and clearance problems. If someone shouts that they always use harnesses, that is not a policy, that is an admission they are living at the bottom of the hierarchy.

If you do use harnesses, the basics are not optional. Use certified anchors, check the clearance below, pick the right lanyard or SRL, manage swing, and train people to fit and use the kit. You also need a rescue plan that you can actually do, within minutes, not just call 999. The Work at Height Regulations 2005 require you to plan for emergencies and rescue, and emergency services are not your rescue plan. Practise it with the kit and people you will have on the day.

If you use harnesses at all, read our piece on working at height rescue plans so your team knows exactly how to recover a person quickly.

Worked example: choosing access for a gutter replacement

You are swapping gutters and fascias on a semi with a small rear conservatory. Eaves height is roughly second storey. The drive is block paving with a soakaway, the back garden is soft ground, and a narrow alley runs down the side. There is a street tree at the front with a low branch and a couple of overhead telecoms lines. Forecast says showers and a stiff breeze. The client wants it done by Friday and does not want the roses touched.

Avoiding the height is out for the replacement itself, but you can still bring jobs down. Pre‑cut and label all trims, joiners and brackets on trestles. Set out lengths on the ground with chalk. Bag fixings, label unions, lay out sealants and wipes. If you are clearing the old gutter first, use a pole system from the ground where you can, so when you are at the eaves you are only fitting, not scooping sludge with cold hands.

Now prevent the fall. Scaffold gives you a full run with guardrails, easy step‑offs and somewhere to stage material. The conservatory at the back means you need a cantilever or a small bridge section, which a decent scaffold firm can sort under current NASC guidance. The front has space for a short independent scaffold with a fan over the pavement if you need to drop old lengths. If you will be there more than a day, scaffold is the sensible choice because you will move along, carry long pieces and need both hands.

A MEWP is tempting at the front if the drive can take the load and you can set outriggers away from the soakaway. Check the bearing capacity under the blocks. If it is just sand and a crate, forget it. The back garden is soft, so a MEWP there is a non‑starter. A tower could work for short sections if you can get it down the alley and level it on decent pads, but leapfrogging a tower around a conservatory in showers gets risky and slow. A ladder should not be your main access for stripping and fitting long runs, it is fine only for short fixes like a bracket tweak. Under the Working at Height Regulations 2005 reg 6, collective protection like scaffold takes priority over relying on people to balance on rungs.

Mitigation still has a place. If you have a short section over the conservatory that cannot be scaffolded, you might use work restraint from a certified anchor on the roof, keeping the worker away from the edge. If there is any chance of fall arrest, you must measure the drop, check for obstructions, and have a rescue plan with kit on site. For most domestic gutter replacements, the right answer is scaffold front and back, with a modest adaptation over the conservatory, and no harnesses unless you hit a weird junction you have planned for.

Turn the hierarchy into RAMS and daily briefings

A hierarchy on paper only helps if it changes what you do. Build it into your RAMS and your morning brief. Start with avoid, then prevent, then mitigate, and write the reasoning. Under the Work at Height Regulations 2005 you must plan the work and make sure the people involved are competent. That means your supervisor knows the sequence, your team knows the access choice, and you have the right kit and inspections done before first use.

Write triggers for changing plan. Wind at site above the machine limit, wet rungs, a blocked pavement that kills your exclusion zone, soft ground after heavy rain, these are reasons to stop and switch. Note who can call it and how you will swap to an alternative that still follows the hierarchy. Dynamic risk assessment is not winging it, it is making a sensible change when reality does not match the plan.

Keep inspection and housekeeping tight. Towers built and inspected by someone trained, tags in place, ties checked, MEWP pre‑use checks done, harnesses logged and inspected, and a clear route to and from the work face. The Work at Height Regulations 2005 require inspections at suitable intervals and after events that could affect safety, and some equipment needs formal records. A tidy platform with toe boards and somewhere to put tools is worth half the battle. It stops the daft reaches and the trip that ends with a boot off the edge.

Questions we get asked

What is the working at height hierarchy?

It is the legal order for controls under the Work at Height Regulations 2005 reg 6. First avoid the height if you can. If you cannot, prevent the fall with collective protection like guardrails and platforms. If there is still a residual risk, mitigate the consequences with things like nets, airbags or personal fall protection, with rescue planned.

When can I use a ladder instead of scaffold or a MEWP?

Use ladders only for short duration, low‑risk tasks where you can maintain three points of contact and you are not carrying heavy kit or leaning out. If the task takes time, needs two hands most of the time, or requires moving along the work face, a ladder is the wrong choice under the Work at Height Regulations 2005 hierarchy.

Do I always need a harness in a MEWP?

In boom‑type MEWPs you should wear a harness and short lanyard to prevent catapult ejection. In scissor lifts, a harness is not usually required if you stay within the guardrails, unless site rules say otherwise. Either way, the platform and mid‑rails are the primary protection under the hierarchy, not the harness. Plan rescue for any situation where a harness could be loaded.

What is better, safety nets or airbags?

Both are mitigation and both are collective. Nets suit large spans under steelwork where you can fix and tension them correctly, often before roof work starts. Airbags or soft landing systems suit smaller areas and fit‑out stages. Choose based on the structure, fixings, coverage and the sequence of the job, following the Work at Height Regulations 2005 duty to reduce the risk so far as reasonably practicable.

Do I need a rescue plan if we use harnesses?

Yes. The Work at Height Regulations 2005 require you to plan for emergencies and rescue. Calling 999 is not a rescue plan. You need a method, kit and people who can carry it out quickly on the actual work area, and you should brief and practise it.

The short version

The working at height hierarchy is avoid, prevent, mitigate under WAHR 2005 reg 6. Turn that into site choices. Bring work down where you can. If you must go up, pick collective protection first, comparing scaffold, MEWP and towers to your job’s ground, duration and handling needs. Ladders are for quick, low‑risk jobs only.

Mitigation sits last, with nets and airbags above personal kit. If you ever reach for a harness, prefer work restraint over fall arrest, and have a real rescue plan. Build the hierarchy into your RAMS and daily briefs so the choice is made before someone is halfway up a rung in the rain.