One late material stops a site. A calculation showing how to identify which orders actually govern the programme.
Procurement is usually reactive: order when the trade approaches. That works for everything available locally and fails for everything that is not, which is how a single item delays an entire project.
The situation
A contractor is planning procurement for a villa and wants to identify which materials govern the programme and when each must be ordered.
Assumptions (illustrative)
- Structure starts week 6, finishing starts week 24, handover week 40.
- Assumed lead time for locally stocked blocks and cement: 1 week.
- Assumed lead time for reinforcement in standard diameters: 2 weeks.
- Assumed lead time for imported floor tiles: 10 weeks.
- Assumed lead time for bespoke joinery from approved drawings: 12 weeks.
- Assumed drawing and approval period for joinery: 3 weeks.
- Assumed lead time for specified sanitary ware: 6 weeks.
- All figures are illustrative assumptions used to demonstrate the method.
Step 1: Identify the trade start dates
Tiling begins week 26, joinery installation week 32, sanitary ware installation week 30.
Procurement dates work backward from when each material is needed on site, not from when the trade is contracted.
Step 2: Backward calculation for tiles
Week 26 less 10 weeks equals week 16 for the order.
The tile decision must be final ten weeks before tiling starts, which is usually before owners feel ready to choose.
Step 3: Backward calculation for joinery
Week 32 less 12 weeks production less 3 weeks drawings equals week 17.
Joinery requires a decision at a similar time to tiles despite being installed six weeks later, because of the drawing stage.
Step 4: Backward calculation for sanitary ware
Week 30 less 6 weeks equals week 24.
Less critical, though selections affect plumbing first fix, which occurs considerably earlier.
Step 5: Identifying the governing item
Joinery at week 17 and tiles at week 16 are the earliest decisions required, both falling during the structural phase.
Finishing decisions govern the programme while the structure is still going up, which is counterintuitive and is why they are missed.
Step 6: Cost of missing the date
A four week delay on tiles stops the finishing sequence, with site overheads continuing throughout.
A decision delayed by four weeks costs four weeks of site overhead plus the knock-on to every following trade.
What changes the answer
- Local alternatives with shorter lead times can remove an item from the critical path entirely.
- Shipping disruption extends imported lead times unpredictably.
- Approval periods within the owner's control are often longer than the supplier's lead time.
- Batching orders reduces cost and couples delivery dates, which introduces its own risk.
What the numbers tell you
- Work backward from installation dates rather than forward from decision dates.
- Include drawing and approval periods, which are part of the lead time.
- Identify which items govern the programme and decide those first.
- Compare a more expensive local alternative against the cost of the delay it avoids.
Limits of this example
Every figure above is an illustrative assumption used to show the method, not a quote, valuation or market rate. Costs, rates, fees and regulations change and must be confirmed with the relevant authority, lender or supplier before you commit.
If you are procuring materials for a project, Domira can specify, source and verify them against the standards your drawings actually require.
Frequently Asked Questions
Which materials most often delay projects?
Items requiring drawings and production, such as bespoke joinery, and imported items with shipping exposure. Materials available from local stock are rarely the problem, which is why identifying the exceptions early is the whole exercise.
Should materials be ordered as early as possible?
Order early enough to arrive when needed, with a buffer, but not so early that materials occupy site space and risk damage. Delivery scheduled against the programme is better than delivery as early as possible.
Who should manage procurement, the contractor or the owner?
Whoever controls the decision should carry the lead time responsibility. Where owners select finishes personally, the programme consequence of late selection should be understood and reflected in the contract.
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