Who is responsible for scaffold safety: client, contractor, or designer?

If you ask three people this on a building site, you’ll get four answers and at least one shrug.

The reality is: scaffold safety is shared — but the duties are different depending on whether you’re the client, principal contractor / contractor, scaffold contractor, principal designer, or scaffold designer. Under CDM 2015, each dutyholder must do their part, and nobody gets to outsource their legal responsibilities with a purchase order.

This post explains who is responsible for what, and where scaffold design fits in.

The simple rule: the person controlling the risk must manage it

Scaffolding safety isn’t one job; it’s a chain:

• Design (is the proposed configuration structurally safe and buildable?)

• Supply / erection (is it erected correctly and altered safely?)

• Use (is it used within its limits, and kept stable?)

• Inspection (is it checked at the right intervals and after events?)

• Change control (are alterations controlled and re-designed when needed?)

Different dutyholders sit on different links in that chain.

1) The Client’s responsibilities

Under CDM 2015, the client must make suitable arrangements for managing health and safety on the project. On multi-contractor projects, the client must appoint a Principal Designer (PD) and Principal Contractor (PC), and ensure those appointees have the right skills/knowledge/experience.

In scaffold terms, the client should ensure:

• competent organisations are appointed (including scaffolding and design where required),

• adequate time and resources are allowed (rushed scaffolds are where “interesting” things happen),

• the project team has the information they need to plan safely.

Important nuance: the client doesn’t normally “own” day-to-day scaffold control on site — but they do have a duty to set up a management structure where scaffolding can be planned, designed (when needed), erected, inspected and used safely.

2) The Principal Contractor / Contractor responsibilities

On projects with more than one contractor, the Principal Contractor controls the construction phase and must plan, manage and monitor health and safety during that phase.

Practically, for scaffolding this usually means the PC (or the contractor controlling the work area) is responsible for making sure:

• the right scaffold solution is specified (TG20/TG30 compliance route vs bespoke design),

• scaffolds are only used once they’re safe to use,

• inspection regimes happen and are recorded,

• changes/alterations are controlled and communicated,

• users don’t overload or misuse the scaffold.

This is where many projects fall over: the scaffold might be “designed well”, but then gets altered, loaded, sheeted, or partially struck without proper control.

3) The Scaffold Contractor (erector) responsibilities

The scaffold contractor is responsible for erecting, altering and dismantling scaffolding safely. HSE points to NASC guidance (e.g., SG4) or equivalent manufacturer guidance for system scaffolds as a route to safe erection practices.

The scaffold contractor’s duties typically include:

• competent erection/alteration/dismantle,

• building to the provided design or compliance sheet,

• installing ties/bracing/stability measures correctly and progressively,

• ensuring that agreed handover and tagging procedures are followed,

• cooperating with site management on inspection and change control.

If the job is TG20/TG30 compliant, the scaffold contractor must still ensure the build genuinely matches the compliance requirements — “close enough” is not a compliance strategy.

4) The Scaffold Designer responsibilities (that’s us)

Under CDM 2015, designers must eliminate, reduce or control foreseeable risks through design and provide information to others so they can carry out their duties.

For scaffold design specifically, our responsibility is to provide:

• a design that is structurally adequate for the stated loads and constraints,

• clear drawings, tie patterns/requirements, bracing and stability provisions,

• assumptions and limitations (e.g., max lift loads, tie capacities, “no sheeting unless designed”, sequencing notes),

• any residual risks that the contractor must manage during erection/use/dismantle.

What designers are not responsible for: physically building the scaffold, policing it daily, or controlling unauthorised alterations on site. That sits with those managing and carrying out the construction phase — typically the PC and scaffold contractor.

5) The Principal Designer responsibilities (pre-construction coordination)

The Principal Designer coordinates health and safety in the pre-construction phase, including ensuring relevant information is shared and design risks are managed.

Where scaffolding is significant (temporary roofs, sheeted scaffolds, complex access, public protection), the PD role often affects:

• whether a design is required and when,

• ensuring designers get the information needed (façade constraints, load requirements, sequencing constraints),

• ensuring residual risks are communicated into construction planning.

The “inspection” question: who ensures scaffolds are inspected?

Scaffold inspection duties are driven by the Work at Height Regulations 2005, which include requirements around the safety conditions and permissible loadings for scaffolding and the need to manage changing weather conditions that could affect safety.

In practical terms on most sites:

• the PC / site management typically ensures the inspection regime is in place and records are kept (because they control the construction phase), and

• inspections must be carried out by a competent person appropriate to the scaffold type and complexity. (Competence is a core HSE expectation.)

Where responsibility commonly goes wrong

Here are the repeat offenders:

1. Design provided, but scaffold altered without review
   Adding a loading bay, removing ties, cutting in a hoist, adding sheeting/signage — these are design changes.

2. “It’s TG20” used as a blanket excuse
   TG20/TG30 compliance only works if you stay within scope and follow the requirements exactly.

3. Client assumes “the contractor has it”
   Clients must still ensure the project is set up and resourced to manage risk properly.

4. No clear owner for inspections and change control
   Scaffolds don’t fail only at erection — they fail after impact, weather, unauthorised alterations, and creep loading.

What we need from you (so responsibilities don’t blur)

To keep everyone in their lane (and keep the scaffold safe), we typically need:

• who the PC / site controller is (and who signs off changes),

• intended use and loading (access only, loading bays, hoists, sheeting),

• tie constraints and façade type,

• any sequencing constraints (phasing, live areas, public interface),

• confirmation of who will manage inspection and alteration control on site.

That way the design reflects reality — and the site team knows what can and can’t be changed without review.

Bottom line

• Client: sets the project up properly; appoints competent PD/PC where required.

• Principal Contractor / contractor in control: manages scaffold safety in use, inspections, and change control during the construction phase.

• Scaffold contractor: erects/alters/dismantles safely and to the design/compliance requirements.

• Designer (scaffold design): designs out risk where possible, provides a safe design with clear limitations and information.

Everyone has a piece of the duty. The safest sites are the ones that treat scaffolding like temporary works: designed when needed, controlled always.