Why programmes slip
Four structural causes, all specific to the exercise. They relate to discoveries, permits and participants.
Discoveries create stopping points. The time to record, characterise, price and decide adds to execution time.
Trades follow one another less smoothly. In new build, trades succeed each other in a predictable order; in renovation, access to areas depends on the progress of other trades and sometimes on occupation.
Specialist contractors have their own lead times. Some operations fall to approved firms whose availability does not align with the project programme.
Inspections impose milestones. Commissioning may depend on an inspection whose date cannot be freely chosen, as the article on the state of the electrical installation explains.
How to write a period that holds
Three principles, worth more than an optimistic duration. They make the calendar credible and defensible.
Fix a verifiable triggering event, not a date. Grant of permit, vacant possession, receipt of a document: specifying the event matters more than specifying duration.
Break it into phases rather than announcing a global period. A global period slips away at the first deviation; phases allow the delay to be located.
Provide explicitly for the effect of addenda on the programme, covered in the article on addenda.
A period without a triggering event does not allow delay to be established, which renders inoperative any penalty clause resting on it.
The five causes of interruption
Their allocation must be written, failing which each becomes an argument. The causes of suspension are recorded as they arise.
| Cause | Natural allocation |
|---|---|
| Technical discovery | the building's contingency |
| Awaiting a decision | whoever had to decide |
| Supply failure | the contractor, save force majeure |
| Third-party intervention | per the agreed organisation |
| Access unavailable | whoever had to vacate |
The second line is the most frequent in renovation, and it is the one contracts address least.
Awaiting a decision costs without producing. The contractor mobilises or demobilises, and either way that is paid for.
The effect of occupation
A factor specific to renovation, often underestimated at quotation stage. It concerns occupation of the premises during the works.
A building occupied during works imposes constraints, working hours, protection, daily reinstatement, phasing by area.
Those constraints affect outputs without changing quantities, connecting with the point developed in the article on measurement in renovation.
They must be described in the contract, failing which the contractor prices work on a vacant site and discovers the constraints on starting.
A project on an occupied site is not an ordinary project done more slowly. It is a different organisation, priced differently.
What to provide for on a stoppage
Four stipulations, simple and rarely present. They organise how interruptions are handled.
Written notification of the stoppage, with its cause and date.
The fate of site installations during the stoppage, an item quickly significant.
Conditions of resumption, notably a notice period allowing the contractor to remobilise.
The effect on the overall period, the stoppage suspending rather than consuming it.
Those four points take a few lines to write and avoid arguments that themselves concern substantial amounts.
What this means for a professional
Four rules.
Write periods by phase, with verifiable triggering events.
Provide for the allocation of interruptions, particularly waits for decisions.
Describe occupation constraints in the contract, before pricing rather than after.
Notify any stoppage in writing, with its cause, which governs any later discussion.
This article sets out drafting principles at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.