> Disclaimer: SiteKiln gives you plain-English information, not legal or health and safety advice. Always follow your site-specific risk assessments and talk to a qualified professional.
The short version
Temporary works (things like propping, formwork, falsework, temp stability, edge protection, some scaffolds, temporary ramps and platforms) have to be properly designed, checked and managed, the same as permanent works.
Under CDM, the contractor in control of the job carries the can for managing them; BS 5975 and TWf guidance then spell out the usual setup: a Temporary Works Coordinator (TWC) to manage the process, Temporary Works Designers (TWDs) to do the calcs/details, and checks by competent people before you load or rely on anything.
Why it matters
A lot of the nastiest collapses are about temporary works -- not the final building -- failing under load, in high winds, or during alteration or strip-out.
Things like back-propping, needles, facade retention, tower crane bases, hoarding, excavations, temporary works to permanent structures -- these are all classic failure points if they're not designed, checked, and used exactly as intended.
HSE see poor temporary works management as a sign that the job isn't under control; they use BS 5975 and TWf guidance as the benchmark for "good practice" even on smaller projects.
Who does what -- plain English roles
On a typical job, you'll see these roles (even if they don't always use the titles):
Client (CDM): picks the project team and must ensure there are suitable management arrangements for health and safety, including temporary works.
Principal designer / designers: must think about how the permanent works will be built, foresee where temporary works will be needed, and pass that information on -- not pretend construction sequence is someone else's problem.
Principal contractor / contractor in control: legally responsible for making sure temporary works are planned, designed, checked, installed, used and removed safely -- that's where HSE point first if something collapses.
Temporary Works Coordinator (TWC) -- BS 5975 "good practice" role:
- Appointed by the contractor in control.
- Manages the process, not all the detailed calcs: makes sure all temporary works are identified, designed by competent people, allocated a risk category/class, checked where needed, and only loaded/changed/removed with proper sign-off.
Temporary Works Designers (TWDs):
- Engineers or specialist designers who actually design the temporary works (calcs, drawings, sequences) to suit the loads, site conditions and build sequence.
Temporary Works Supervisors (TWSs) / site team:
- Make sure what gets built on site matches the TWD's drawings and the TWC's procedures -- no "modifications" with a gas axe or extra packers because it "looked okay".
BS 5975 isn't law, but HSE call it "industry consensus good practice" and expect projects to have arrangements that achieve the same level of control, even if titles differ.
Who is liable when temporary works fail?
If temporary works collapse, move, or don't perform as they should, HSE and insurers will look at several layers:
Contractor / principal contractor (your LTD if you're running the job):
- Primary duty under HSWA and CDM to plan, manage and monitor the work safely, including temporary works.
- Liable if there was no coherent temporary works process, if designs weren't obtained or followed, or if unapproved changes were allowed.
Temporary Works Designer(s):
- Liable for negligent design -- wrong assumptions, mis-calculated loads, designs that weren't buildable as drawn, etc., subject to what they were asked and what information they got.
Permanent works designer (in some cases):
- If they failed to flag temporary works needs, stability issues or sequencing risks that a competent designer should have foreseen.
TWC / management individuals:
- Personal liability can arise if someone in a controlling role was grossly negligent or ignored clear problems -- but usually the company is front and centre.
Subcontractors / TWS / site team:
- Liable where they depart from design, cut corners, or make changes without approval, especially if that's why the failure happened.
In reality, responsibility is often shared -- but if you're the small builder or principal contractor, you're almost always in the frame if the temporary works were under your control.
For a small builder -- what you actually need to do
If you're the main/only contractor on a job:
Identify temporary works early
Anything that temporarily supports, restrains, provides access or protects -- propping, formwork/falsework, temporary cut-and-prop, facade retention, temp roofs, edge protection, hoardings, big excavations, crane bases, some scaffolds and towers.
Decide who will design them
- Use competent engineers or proprietary systems (with proper load limits) for anything beyond very simple, low-risk items.
- Don't "design" needle beams, back-propping or facade retention on the back of a fag packet.
Put someone in charge of temporary works
- On small jobs, this might be you wearing the TWC hat by another name -- but you still need a procedure: you log each bit of temporary works, get design/check as needed, keep drawings on site, and don't let anyone alter/remove it without sign-off.
Follow the design and control changes
- Build what's on the drawing; if site conditions differ or someone wants to tweak something, get the designer to agree a change -- don't bodge it.
- Make sure temporary works are inspected before use and at intervals, especially after major weather or impacts.
For a small subcontractor, your play is to:
- Be clear what temporary works you're responsible for (e.g. your own formwork/scaffold) and what the PC is providing.
- Ask for designs and limits where you're being asked to load or rely on others' temporary works (e.g. "how much can this slab be back-propped for my kit?").
You don't have to be a structural engineer to get this right, but you do need to make sure someone competent is doing the sums -- and that nobody quietly "improves" their design with a sledgehammer or a saw.
What to do next
- List every piece of temporary works on your current job -- propping, formwork, edge protection, shoring, hoardings -- and check each one has a design or specification behind it.
- If you're the main contractor, make sure someone is wearing the Temporary Works Coordinator hat, even if it's you.
- Never alter or remove temporary works without sign-off from the designer or TWC -- no "quick fixes" with a gas axe.
- Keep temporary works drawings on site where the team can see them, not filed in the office.
- If you're a subcontractor, ask the PC what temporary works you're relying on and what limits they have.
Sources
- Construction (Design and Management) Regulations 2015 -- planning and management of construction work including temporary works.
- Health and Safety at Work etc. Act 1974 -- general duties.
- HSE -- Temporary works SIM and FAQs: management expectations and BS 5975 as industry good practice.
- BS 5975 / industry commentary -- TWC and TWS roles, procedural control and design/check requirements.
Disclaimer
This guide is general information for small UK construction businesses and trades, not formal legal or engineering advice.
SiteKiln is not a law firm and this page is not a substitute for getting advice on your specific situation.
Health and safety law, CDM and industry standards including BS 5975 are updated from time to time, and how they apply will always depend on the exact facts on your project and your role.
If you're dealing with a temporary works failure, collapse, enforcement notice or complex structural situation, get specific advice from a competent structural/temporary works engineer and/or solicitor before you make big decisions.
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