Mobile scaffold tower rules: PASMA, 3T and what the law requires

What mobile scaffold tower regulations actually require

A mobile tower is still a scaffold. Mobile scaffold tower regulations are not some separate rulebook, they are part of the Work at Height Regulations 2005. That means plan the work, choose suitable equipment, and make sure only competent people assemble, alter and dismantle it. If you would not send a lad up a fixed scaffold with missing guardrails, do not accept it on a tower. The law does not care if it is a Sunday in a quiet unit or a wet Tuesday in a live school, the duty is the same.

Competence is a legal requirement in the Work at Height Regulations 2005. In plain terms, the person building and using the tower needs the right training, knowledge and experience for that make and model. PASMA is the recognised training route for mobile towers across the UK, but it is not a legal monopoly. If you can prove another route delivers equal competence, that can be fine. On most sites, PASMA cards are the simple way to show it.

Design matters too. Buy or hire towers that comply with BS EN 1004, the product standard for mobile access and working towers. That standard sets things like guardrail heights and load classes so you are not gambling with oddball kit. Mixing parts from different systems is asking for trouble. If the braces do not match and the pins sit proud, you will end up bodging something that will let go when someone leans on it.

Competence and PASMA: what counts

We see sites where the foreman thinks anyone who can build flatpack can build a tower. That is how you end up with a baseplate on a kerb and a caster wheel hanging over fresh tarmac. The Work at Height Regulations 2005 require competence for those who assemble, use, and inspect towers. PASMA training is the common proof. The standard course covers manufacturer manuals, 3T and AGR builds, hazards like overhead lines, and the inspection routine.

Training is only half of competence. You also need the right experience and supervision. If a labourer did PASMA three years ago and has not touched a tower since, pair them with a competent person. Keep the manufacturer’s manual on site and follow it line by line. That manual is not a suggestion, it is the build sequence and the limits for platform height, stabilisers and wind.

If you are a specialist team working to a different training scheme, document it. Show the syllabus, show assessments, and keep records of toolbox talks and on the job supervision. The Work at Height Regulations 2005 do not mandate a specific card, they expect you to be able to prove your people are competent for the task and the equipment in front of them.

If you are writing up the job, this Scaffolding RAMS Template helps you capture the sequence, controls and inspection regime in one place.

3T versus AGR: two safe ways to build

Most falls on towers happen during assembly and alteration. You can avoid the nasty bit by using a safe system that gives you guardrail protection before you climb to the next level. That is what 3T and AGR are for. Both are accepted methods and both are taught on PASMA. The method you use needs to match the kit in your hands and the build sequence in the manual.

3T, or through the trap, means you install the next level’s guardrails while standing in the trap of the platform below, so you never stand on an unprotected edge. It takes a bit of discipline. Clip the braces in, check they are level, then climb up within the ladder bay. Do not be tempted to pop your head out and reach across an open side. That is how people end up with a bruised rib and a bent toe board.

AGR, or advanced guardrail, uses a dedicated frame or telescopic guardrail that you put in from the level below so the next platform is already protected on the open sides. It is tidy and fast once you know the sequence, especially on repetitive builds indoors. Some systems are AGR only, others offer both. The key point is simple. Pick one proven method and stick to it properly.

Inspections and records: after assembly, every 7 days and after changes

Once the tower is up, it becomes a working platform and needs inspecting. Under the Work at Height Regulations 2005, you must inspect a tower after assembly, at intervals not exceeding seven days, and after any event likely to affect its safety, like high winds or being hit by plant. If a person could fall 2 metres or more, you must also make a written inspection report that meets Schedule 7 of the Work at Height Regulations 2005 and keep it on site until the work is complete.

What does a competent inspection look like in the real world? You start at the base. Check the ground is firm and level. Wheels locked and adjusted so the frames are plumb. Stabilisers fitted at the right angle, with feet on the deck and not on a stray offcut. Then go up level by level. All braces present and correctly oriented. Platforms fully decked with trapdoors closing the right way. Internal ladders secured. Guardrails at the right heights. Toe boards fitted. No gaps where a tape measure or drill could roll out.

Daily pre use checks are just as important. They do not replace the seven day inspection, but they find the silly things. A missing clip. A brace moved to hang a jacket. A bent frame that was fine yesterday and is not fine after the painter drove the scissor past it. Record formal inspections, fix what is wrong, and tag the tower to show status if that is how your site runs. Tags help communication, they are not a legal requirement on their own.

If your site uses scaffold tags, make sure your team knows what the colours and cards mean by reading scaffold tags.

Stabilisers, height limits and wind: follow the manual, not pub wisdom

Most tower problems start at the base. Manufacturers give a height to base ratio and a stabiliser configuration for each platform height and for indoor or outdoor use. Respect it. If the manual says fit the long stabilisers at 4.2 metres outdoors, you fit them. If it says tie to the structure at a certain height because wind could push the tower, then you tie it. Guesswork and rules of thumb get people hurt.

Outriggers and stabilisers are not decoration. Set the feet at the specified angle and extension. Use base plates or pads if the ground is soft or you are on block paving. Indoors on a smooth slab you still need them at relatively modest heights. Outdoors, wind becomes a bigger factor. Many manufacturers give wind speed limits for in use and out of use. If the weather turns, drop the platform and secure the tower. A clattering tower on its side in the car park is not a good look.

Do not climb the outside frame. Use the internal ladder with three points of contact, keep the trap closed when you are working, and never stand on guardrails. If the job needs more reach, adjust the tower properly or move and rebuild to suit. A quick stand on the toe board to get that last scrub of filler is how a cheap day rate ends up as lost time and paperwork.

Common failures on towers and how to avoid them

The greatest hits are the same on every site. Moving a tower with someone or materials on it. Leaving out braces because you think it makes boarding quicker. Building on a slope and blaming the laser. All of these feature in HSE accident investigations, which is why inspectors get grumpy when they see them. If a caster wheel catches a cable tray or expansion joint while someone is halfway up, you will not like the outcome.

Never move a tower with anyone or anything on it. Empty it, lower the platform if needed, check for overhead obstructions, and push from the base at the frame uprights. Unlock, move slowly on a clean route, then re lock and re level. If you are outside, factor in wind. Moving a sail on wheels in a gust is asking for a topple. If the route is rough, break it down and carry the frames. The extra ten minutes is cheaper than a broken wrist.

Missing braces are a classic. If your brace count on the pallet does not match the manual, stop. Towers rely on triangulation. Leave one out and the frame will sway, then rack, then twist, and the platform will not sit right. People try to fix this with lashings or by leaning it into a wall. That is not a fix. Fit the correct braces in the correct position or do not use the tower.

Ground conditions get ignored until they bite. Polished painted floors with dust behave like ice. New screed can crush under point loads. Block paving caves in if you set a stabiliser foot on a single block on the edge of a gully. Spread the load with pads where needed and do not guess. If the leg sinks overnight, your morning climb is on a lean and your guardrails are no longer at the right height.

Questions we get asked

Do I legally need PASMA to build a mobile scaffold tower?

You legally need competence under the Work at Height Regulations 2005, not a specific card. PASMA is the recognised training route for towers and is widely accepted by clients, but the law allows any route that demonstrably provides competence for the equipment and task.

How often must a mobile tower be inspected in the UK?

Inspect after assembly, then at intervals not exceeding seven days, and after any event likely to affect safety under the Work at Height Regulations 2005. If a fall of 2 metres or more is possible, complete and retain a Schedule 7 inspection report.

What is the difference between 3T and AGR on towers?

3T, or through the trap, has you install guardrails for the next lift from the platform below, so you never work at an unprotected edge. AGR, or advanced guardrail, uses dedicated guardrail units that are installed from below so the next platform is already protected. Both are accepted safe systems when used as the manufacturer intends.

Can you move a mobile scaffold tower with someone on it?

No. You should never move a tower with a person or materials on it. Moving occupied towers is unsafe and conflicts with your duty to organise and use work equipment safely under the Work at Height Regulations 2005. Empty it, unlock, move on a clear route, then re level and re inspect.

Do I need stabilisers on a short indoor tower?

Usually yes. Manufacturers specify stabilisers and height to base ratios for each platform height, even indoors. Follow the manual exactly. If the configuration calls for stabilisers or ties at your intended height, fit them. Do not rely on rules of thumb.

Are scaffold tags legally required on mobile towers?

Tags are not mandated by law, but they are a good way to show inspection status and control use. The legal duty is to inspect and, where applicable, record under the Work at Height Regulations 2005. Many sites require tagging as part of their procedures.

The short version

Mobile towers are covered by the Work at Height Regulations 2005. That means competent people, a safe assembly method like 3T or AGR, and inspections after assembly, every seven days where a fall of 2 metres or more is possible, and after any event that could affect safety. PASMA is the recognised route to competence, but not a legal monopoly.

Fit stabilisers and respect the height to base ratios in the manufacturer’s manual. Do not move occupied towers, do not leave out braces, and do not climb the outside. Keep the manual on site, record your inspections, and tag if your site uses a tagging system. If the weather is foul or the ground is suspect, drop the platform and make it safe before anyone goes up.