SiteIt's the Friday before the shut. Production finishes at two. Your plan has 140 jobs on it, and you found out on Wednesday that the gearbox for line 3 won't land until the following Thursday.
The electrical contractor can send two people instead of four. The scaffold firm wants a permit nobody has written. And someone from production has just added "while you're in there, can you look at the wrapper?"
By Sunday night you'll be choosing which jobs to drop. By Monday morning production will want the line back on time anyway.
Shutdowns rarely fail on the tools. They fail because the planning started six weeks too late.
Why 12 weeks
Twelve weeks gives you time to order long-lead parts, book the people, and write the paperwork without a rush. It isn't magic. A small weekend shut might need less. A full rebuild might need much more. But for a normal one or two week shutdown on a factory or warehouse site, 12 weeks is about where the trouble starts if you haven't begun.
HSE's maintenance guidance backs the basic idea. It suggests you "try to use downtime for maintenance", and do the work "before start-up or during shutdown periods" so you're not fighting production for the machine (HSE, maintenance of work equipment). A shutdown is the best chance you get all year. Waste it and you're doing the same jobs as breakdowns in March.
Weeks 12 to 10: fix the scope
Start with a list of every job anyone wants done. Pull it from:
- the PPM tasks that need the machine fully down
- open defects from LOLER reports and PUWER inspections
- the breakdown log, for repeat failures that need a proper fix
- condition monitoring readings that are trending the wrong way
- production's wish list, and the projects team's installs
Then rank it. Safety items and statutory defects first. Then jobs that stop repeat breakdowns. Then everything else. Our guide to criticality ranking helps here.
At the end of week 10, freeze the scope. New jobs can still come in, but only if something of the same size comes out. Scope creep kills more shutdowns than any failed part.
Weeks 10 to 8: parts and people
Order anything with a long lead time now. Gearboxes, bespoke drives, bearings in odd sizes, conveyor belting cut to length. Chase the supplier for a firm date in writing.
Then count the hours. Go through each job and estimate the hours and the skill it needs. Mechanical, electrical, controls, specialist. Add it up by day and by trade. Compare it with your own team, after holidays and the people you need to keep on site cover.
That gap is your contractor and agency need, and this is the point to book it. Good shutdown engineers get booked early, because every site wants them in the same weeks. Leave it to week 4 and you'll take whoever's left. If you're short of a controls engineer on day three, the line 3 rebuild sits half done while you pay everyone else to wait. We cover the timing in more detail in booking extra hands for a planned shutdown.
Weeks 8 to 6: check if it's construction work
This one catches sites out. Some shutdown work falls under the Construction (Design and Management) Regulations 2015. The definition of construction work includes the installation, maintenance, repair or removal of services "which are normally fixed within or to a structure", such as electrical, compressed air or hydraulic services (CDM 2015, regulation 2). So replacing a ring main or a section of the site's air pipework could count, even if fixing a machine doesn't.
If it is construction work, you have client duties. A project is notifiable to HSE if it's scheduled to last longer than 30 working days* with more than 20 workers* on site at the same time, or to exceed 500 person days* (CDM 2015, regulation 6). Most maintenance shuts won't hit that. A big install might. Check now, not in week 1.
Weeks 6 to 4: paperwork and permits
Get risk assessments and method statements from every contractor, and read them. Write your own for the jobs your team is doing. Our post on permits to work covers which jobs need a formal permit. HSE notes that a formal system such as a permit to work is "required in some cases" for high-risk maintenance (HSE, maintenance of work equipment).
A shutdown puts many employers on one site at once. The law expects you all to co-operate when you share a workplace, "whether on a temporary or a permanent basis" (Management Regulations 1999, regulation 11). HSE's leaflet on using contractors says to agree the measures to control risk "before work starts", and puts it bluntly: "Don't assume someone is competent, check it yourself" (INDG368). Our guide to contractors on site has the detail.
Weeks 4 to 1: the plan on the wall
Build a day-by-day plan. Each job gets a start, a finish, a trade, a name and an isolation. Watch for clashes. Two crews can't share one isolation without a clear lock-off plan. The scaffolders need to finish before the fitters start. The crane can't be in two places.
Plan the hours too. Shutdowns are where long days creep in. HSE's guidance on fatigue warns that "problems with overtime and shift-swapping may indicate inadequate resource allocation and staffing levels" (HSE, fatigue). If your plan only works with your team on 14-hour days for a fortnight, you don't have enough people.
In the last week, run pre-shutdown checks. Parts on site and checked against the order. Tools and lifting gear in date. Inductions booked for every contractor. Spares for the jobs you'll open up and find worse than you expected.
Plan the restart as hard as the stop
Most plans end on the last job. They should end with the line running.
Build in time to test, run in and sign off each machine. Kit you've moved or rebuilt may need an inspection before it goes back into use. PUWER requires one where safety depends on installation, including "after assembly at a new site or in a new location" (PUWER, regulation 6). Keep some of your best people back for the first shift after start-up. That's when the problems show. See restarting after a long stop.
What to do on Monday
- Set the date of your next shutdown and count back 12 weeks. Put the scope freeze in the diary.
- Start the job list today, from PPM, defects, the breakdown log and production.
- Find every part with a lead time over four weeks and order it.
- Add up the hours by trade, and book the people you're short of now.
* CDM notification thresholds correct as of 29 September 2026. Check the CDM Regulations 2015 on legislation.gov.uk for the latest.