A subcontractor is a firm that carries out a defined part of a building project under contract to the main contractor. The subcontractor’s contract is with the main contractor, not with the client. That contractual chain determines who you go to when something goes wrong.
How the chain works
- Client — holds one contract, with the main contractor
- Main contractor — responsible for the whole of the works, the programme and coordination
- Subcontractor — provides a trade or specialism: mechanical and electrical services, roofing, plastering, tiling, windows
The main contractor remains liable to the client for the work of its subcontractors. If the plastering is defective, the client pursues the main contractor — even though the main contractor did not do the work.
In practice
Subcontracting is the norm rather than the exception. Almost every house is built by a chain of specialist firms:
| Element | Usually subcontracted |
|---|---|
| Structure / brickwork | Often the contractor’s own labour |
| Mechanical and electrical | Almost always subcontracted |
| Roof covering | Almost always subcontracted |
| Windows and glazing | Usually subcontracted |
| Finishes (plaster, tiling, floors) | Usually subcontracted |
What clients should watch
- Ask who is doing the work — establish at tender stage which packages are being sublet and to whom
- Put coordination in writing — the main contractor is responsible for sequencing all parties; make that explicit in the contract
- Pay through the main contractor. Paying a subcontractor directly breaks the chain and can weaken your position on defects
- Check insurance and status. Ask for evidence of public liability cover, and be aware that tax and employment rules for construction supply chains can create obligations for the party above
- Check warranties. Confirm whether the guarantee on, say, the roof covering or the heating system runs through the main contractor or directly with the manufacturer
Related terms
- Main contractor
- Contractor
- Building contract
- Tendering
- Construction costs
- Retention
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