Direct costs vs indirect costs.
Every construction cost falls into one of two categories. Direct costs belong to a specific work item; indirect costs support the project as a whole. Getting the split right is the foundation of reliable pricing.
Authored by Alexandr Vreme & Maksym Vasylkov
Published — Next review
What are direct costs?
Direct costs are expenses that can be measured and assigned to a specific work item or measured element of the project. If you can say "this cost exists because we are building that wall," it is probably a direct cost.
Common direct cost categories in construction include:
- Labour — wages and employment costs for operatives working on a specific activity (bricklayers laying a cavity wall, carpenters fixing roof trusses).
- Materials — bricks, blocks, cement, timber, plasterboard, insulation, drainage goods, and every other item that becomes part of the works.
- Plant — hired or owned equipment allocated to a measured item, such as a telehandler for roof loading or a mini-digger for foundation excavation.
- Subcontractors — specialist packages such as steel erection, M&E installations, or cladding, where the subcontractor's price maps to a defined scope.
What are indirect costs?
Indirect costs (often called preliminaries or project overheads) support the project but cannot be allocated to any single measured item. If the cost would still exist even if one particular work item were removed, it is indirect.
Typical indirect costs include:
- Site management and supervision
- Welfare facilities (toilets, canteen, drying room)
- Temporary services (water, electricity, telecoms)
- Scaffolding and hoardings
- Site security and fencing
- Traffic management and dust control
- Waste disposal and skip hire
- Health and safety documentation and inductions
Miniature example: single-storey extension
A typical rear extension might break down as follows:
| Cost item | Amount | Classification |
|---|---|---|
| Excavator and digger driver (1 week) | £1,250 | Direct — plant |
| Concrete, steel, blocks, insulation | £4,800 | Direct — materials |
| Bricklayer and general labourer (2 weeks) | £2,600 | Direct — labour |
| Welfare cabin hire (6 weeks) | £900 | Indirect — preliminaries |
| Scaffolding (4-week hire) | £1,600 | Indirect — preliminaries |
| Waste skip and disposal | £320 | Indirect — preliminaries |
| Total | £11,470 | Direct: £8,650 / Indirect: £2,820 |
Common mistakes
- Burying preliminaries in unit rates. Spreading welfare, security, and supervision costs across individual measured items seems convenient but makes every rate uncompetitive when comparing against a tender that has priced them separately.
- Classifying all labour as direct. The site manager's salary is usually indirect (preliminaries), not a direct cost of any single trade — unless allocated under a specific supervision item.
- Forgetting time-related costs. Welfare hire, security, and temporary services are indirectly proportional to programme duration. Extend the programme and you extend these costs, yet many estimators treat them as fixed.
- Double-counting overheads. Charging preliminaries as a percentage add-on while also embedding supervision costs in hourly labour rates creates a hidden overlap.
Questions to ask
- Are welfare facilities, supervision, site security, and waste disposal included in preliminaries or spread across the unit rates?
- Does my pricing clearly show the split between direct costs and indirect overheads so the client can see what they are paying for?
- If the project programme extends by two weeks, how much does each indirect cost line increase?
- Am I recovering my indirect costs proportionally across projects, or are small jobs subsidising large ones?
Related guides and tools
Deepen your understanding of cost structure with our guide to preliminaries and site overheads and learn how overheads and profit fit into the final price. Use the Construction Estimator to build a fully classified cost breakdown.