Site Instruction vs Variation – Why the Difference Matters
On most construction sites, instructions come in many forms: verbal directions, emails, marked-up drawings, site meeting notes, or formal written site instructions. Not every instruction is automatically a variation that you can claim extra money for.
Under the standard SA-2017 Subcontract Agreement (Section 9), the distinction is important and the process is clear.
What is a Site Instruction?
A site instruction is simply a direction from the main contractor about how the work should be carried out. It might confirm something already in the contract, clarify a detail, or change the sequence of work. On its own, a site instruction does not automatically mean you will be paid extra.
What turns work into a Variation?
A variation is a change to the original scope, quantity, quality, or method of the subcontract works. Under SA-2017:
- The main contractor can issue a written instruction to vary the works (clause 9.1.1).
- If you receive an instruction and believe it involves a variation, you must notify the main contractor in writing within the time stated in the Specific Conditions (commonly 5 Working Days – clause 9.1.3).
- You must then submit a price and supporting details within the required timeframe (clause 9.2.2).
If you do not notify within the required period, the work may not be treated as a variation at all.
The practical sequence that protects you
- Receive a written instruction (or immediately confirm a verbal one in writing).
- Decide whether the instruction changes the original scope or cost.
- Notify the main contractor in writing that you consider it a variation and that additional costs will apply.
- Submit a properly substantiated variation claim with the additional costs, labour, materials, and any other supporting evidence.
- Only include approved variations in your monthly payment claim.
Where subcontractors commonly lose money
- Treating every site instruction as automatically payable extra work.
- Doing the work first and trying to claim it later without proper notification.
- Missing the notification deadline.
- Submitting a variation claim with weak or missing supporting information.
- Bundling unapproved variations into the progress claim and having them scheduled at nil.
Why this matters for cash flow
When variations are not properly notified and substantiated, they are frequently declined or deferred. That money either arrives late or never arrives at all. Over a project, the cumulative effect can be significant.
The subcontractors who protect their margin treat every instruction as a potential commercial event. They record it, assess it, notify it, and evidence it while the work is still fresh — instead of trying to reconstruct it weeks later at claim time.
That disciplined approach is exactly what Subbie HQ is designed to support.