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Construction

Coordinating several firms in one window

Four firms, one window and a sequence that allows no improvisation. If one cannot get in, the other three do not work either.

Updated on 13/08/2026

Your window does not admit one firm: it admits four, in a specific order, because one cannot start until another finishes. **Your job is not to execute, it is to make sure all four can** — which means a documentary problem in any of them, however small, becomes a problem for the whole operation.

Why the risk does not add, it multiplies

Firms in the windowIf each fails 1 time in 20Chance of a clean window
One5%95%
Two5%90%
Four5%**81%**
**Eight****5%****66%**

Important

**In this position it is not enough for each firm to carry its own: it all has to be seen together and in advance.** Each will tell you they are ready, and each will say so in good faith, because each looks at its own folder. What nobody looks at —and it is exactly what decides the window— is the whole: whether all four are current at once, on the same date, with the specific people going in that night.

What must be visible at a glance

  1. 1

    All four firms on one screen

    If it means opening four folders, it will not be done four times.

  2. 2

    Detail per person and per machine

    Company level says nothing about who goes in that night.

  3. 3

    What expires between today and the window

    It is the gap that slips through most: at review time it was fine.

  4. 4

    And the planned entry sequence

    Because gaps do not cost the same: the first firm's stops everyone.

Watch out

The costliest failure is **discovering at the last moment that two firms relied on the same subcontractor**, and that subcontractor is not current. Each assumed it was covered because «the other one handles it», and nobody checked. In multi-firm operations it pays to look once at the complete list of who will physically be there, without trusting the contractual chart: the window is stopped by whoever is at the gate, not by whoever signed the contract.

Worth knowing

What coordination duties exist when several firms work in the same place and time, and what falls to the facility owner and to each firm, **is determined by the applicable rules and settled by your prevention service or adviser**. Here we cover the organisational part: how to see the whole before the window rather than firm by firm.

Is each firm not responsible for its own?

It is, and you all still lose the window. Seeing it together is what saves it.

How far ahead do you review?

With enough room for the failing one to fix it. Days, not hours.

And my contractors' subcontractors?

They slip through most. It pays to hold the list of who will physically be there.

A real case

The situation

Four firms say they are ready and one is not.

What you do

  1. Shows the status of all of them at once

What you get

The whole is visible without opening four folders.

The situation

A document expires between the review and the window.

What you do

  1. Warns about what expires on the appointed date

What you get

The gap is caught before it opens.

The situation

Two contractors rely on the same subcontractor unknowingly.

What you do

  1. Records which firms are declared under each contract

What you get

The overlap surfaces before the night.

The situation

Each firm sends documentation in a different format.

What you do

  1. Requests specific documents to a single destination

What you get

Comparing stops being manual work.

The situation

The review is done at company level and one person fails.

What you do

  1. Allows checking per person and per machine

What you get

What actually comes through the gate is what gets checked.

The situation

Chasing four firms occupies someone all week.

What you do

  1. Chases automatically until it arrives

What you get

The week before goes on preparing rather than nagging.

This article answers

  • coordinating several firms in one shutdown
  • contractor entry sequence
  • one firm cannot enter and blocks the rest
  • documentary control of several contractors at once