The principal contractor is the contractor appointed by the Client, under the CDM Regulations 2015, to plan, manage and coordinate the construction phase of a project that has more than one contractor. It is a health and safety role, separate from being the Main Contractor under the building contract, although on most projects the same company holds both.
What the role involves
- Preparing the construction phase plan before the construction phase starts, and keeping it up to date.
- Organising cooperation and coordination between all contractors on site.
- Providing site welfare and making sure the site is secure and has suitable inductions.
- Making sure workers are consulted on health and safety matters and that the principal designer receives what it needs for the health and safety file.
The HSE guidance on principal contractor duties sets out the full list.
Worked example
A main contractor wins an £850,000 extension contract as the principal contractor. It prices the role into preliminaries for a 20 week programme.
| Cost | Basis | Amount |
|---|---|---|
| Site manager | 20 weeks at £1,350 | £27,000 |
| Welfare and site security | 20 weeks at £420 | £8,400 |
| Construction phase plan, inductions, signage | Lump sum | £2,100 |
| Principal contractor costs | £37,500 |
If the programme runs four weeks late, those weekly items add another £7,080, which is a prelims overspend unless an Extension of Time (EOT) and Loss and Expense recover it.
Principal contractor in the cost report
Subcontractors on your project rely on your welfare, supervision and coordination without paying for them in their orders, so those costs sit with you as the principal contractor. Track them against the preliminaries budget by week, not just in total.
Check that your Subcontract orders require each Subcontractor to supply risk assessments and method statements, and that any attendance you promise is written into the order.
If you are a specialist subcontractor on a smaller job with one other contractor, you may be asked to take the principal contractor role, so understand the extra duty and cost before you agree.
Related terms
CDM Regulations, Main Contractor, Preliminary Costs, Subcontractor, Client.
Planyard's job costing shows preliminaries spend against budget as the programme runs, so principal contractor costs are not hidden in general overheads.
