Site Instructions and Supplemental Instructions on the ExAC

During the construction phase, the architect's primary written tool for directing, clarifying, and correcting the work is the Supplemental Instruction. In practice, you'll also hear it called a Site Instruction, an Architect's Supplemental Instruction (ASI), or simply an SI. Under CCDC contracts, these are the same thing — and the ExAC tests your understanding of what they can and cannot do.

This is the document most candidates underestimate. It's not glamorous. It doesn't involve negotiating prices or resolving disputes. But it sits at the top of the change management hierarchy, and the ExAC uses it as the pivot point for an entire category of scenario questions: the architect just discovered something on site — what document do they issue first?

The answer almost always starts with a Supplemental Instruction. Whether it stays there depends on whether cost or time is affected.

What is a Supplemental Instruction?

A Supplemental Instruction (SI) is a written directive issued by the architect (or consultant) to the contractor during construction. It provides additional information, clarifies the contract documents, or directs a minor adjustment to the work — without changing the contract price or the contract time.

That last part is the key. An SI is explicitly limited to changes that have zero impact on cost and zero impact on schedule. The moment cost or time enters the picture, a different instrument is required.

CHOP (Canadian Handbook of Practice for Architects) Chapter 6.6 puts it plainly: if an SI involves changes to the contract price or to the contract time, the architect must then issue a Contemplated Change Notice or Proposed Change Notice, followed by either a Change Order or a Change Directive.

CCDC 24 — A Guide to Model Forms and Support Documents — goes further: it expressly prohibits architects from using Instructions to change elements of the contract. This is a common real-world mistake and a common exam trap.

What an SI can do

• Clarify dimensions, details, or specifications that are ambiguous in the contract documents
• Provide additional information the contractor needs to execute the work as designed
• Direct minor field adjustments that don't affect cost or time — for example, shifting the location of a non-structural partition by 50mm to accommodate an existing condition
• Confirm verbal instructions given during a site visit in writing
• Respond to an RFI (Request for Information) where the answer requires no change to cost or time

What an SI cannot do

• Direct work that adds cost to the contract
• Extend or reduce the contract time
• Substitute materials that change the contract price
• Direct the contractor to perform work outside the general scope of the contract documents
• Override the General Conditions of the contract

The change management hierarchy under CCDC 2

The ExAC tests your ability to pick the right instrument for the right situation. Here is the full hierarchy, from smallest to largest:

How to remember the flow

Think of it as an escalation ladder:

1. SI — "No cost, no time, just clarity." The architect acts alone.
2. CCN — "Something might change." The architect signals the contractor and asks for a price.
3. CO — "We agree on the change." Both the owner and contractor sign off.
4. CD — "We can't agree, but work can't wait." The owner directs the contractor to proceed; the price gets sorted out later.

The Contemplated Change Notice — the step most candidates skip

The Contemplated Change Notice (CCN) — also called a Proposed Change Notice (PCN) or Proposed Change (PC) in CCDC 24 — is the most misunderstood instrument in the hierarchy. It is not a change order. It is not an instruction to proceed. It is a formal notification that a change is being considered, paired with a request for the contractor to provide pricing.

The CCN exists for one reason: to give the contractor an opportunity to price the change before work proceeds. Without it, the architect risks issuing a Change Directive (which forces work to start before the price is agreed) or, worse, issuing an SI for a change that actually affects cost — which is contractually invalid.

When the CCN is required

• The architect identifies a design error or omission that requires correction, and the correction will change the contract price or time
• The owner requests a modification to the scope of work
• Unforeseen site conditions require a change in approach — for example, encountering contaminated soil that wasn't in the geotechnical report
• A substitution is proposed that affects cost

What happens after the CCN

The contractor submits a quotation for the proposed change. If the owner and contractor agree on the price and any time adjustment, a Change Order is issued. If they cannot agree but the work must proceed to avoid delay, the owner issues a Change Directive — and the price is resolved later, often through the dispute resolution mechanisms in CCDC 2 (mediation, then arbitration under CCDC 40).

Change Order vs. Change Directive — the distinction the ExAC loves

This is one of the most frequently tested distinctions in Section 4. Both instruments modify the contract. The difference is consent.

Change Order (CO)

A Change Order is a written amendment to the contract, prepared by the architect, signed by both the owner and the contractor, stating their agreement on the change to the work, the adjustment to the contract price, and the adjustment to the contract time. It is a bilateral agreement — both parties must sign.

Change Directive (CD)

A Change Directive is a written instruction signed by the owner directing the contractor to proceed with a change in the work within the general scope of the contract documents, before the owner and contractor have agreed on adjustments to the contract price and the contract time.

A Change Directive exists because construction doesn't stop for negotiations. If water is coming through the foundation wall and the contractor needs to install a waterproofing membrane that wasn't in the original documents, you can't wait three weeks for a pricing negotiation. The owner directs the work to proceed; the price gets resolved afterward.

The exam question pattern

A typical Section 4 scenario describes a situation where a change is needed on site. The answer choices usually include:

• Issue a Supplemental Instruction (wrong if cost or time is affected)
• Issue a Change Order (wrong if the contractor hasn't agreed to the price yet)
• Issue a Change Directive (correct when work must proceed before agreement)
• Issue a Contemplated Change Notice (correct when there's time to get pricing first)

The trap is always the same: candidates who don't know the hierarchy pick the SI (because the architect issued it on site) or the Change Order (because it sounds like the final answer). The correct answer depends entirely on whether cost/time is affected and whether agreement has been reached.

The architect's authority on site — what you can and cannot direct

Under CCDC 2 (Part 2 — Administration of the Contract), the architect's role during construction is defined carefully. The ExAC tests this definition because candidates often confuse the architect's authority with the contractor's responsibilities.

The architect can:

• Provide general review of the work to determine if it is being performed in general conformance with the contract documents (GC 2.3)
• Reject work that does not conform to the contract documents (GC 2.4)
• Issue Supplemental Instructions for clarifications
• Issue certificates of payment
• Determine the date of Substantial Performance
• Interpret the contract documents when disputes arise between owner and contractor

The architect cannot:

• Direct construction means, methods, techniques, sequences, or procedures — these are the contractor's sole responsibility (GC 3.8 of CCDC 2)
• Guarantee the quality of the work — the architect provides general review, not continuous inspection
• Stop the work — only the owner can issue a stop-work order
• Unilaterally change the contract price or time — only a Change Order (mutual) or a Change Directive (owner-signed) can do this

RFIs and their relationship to SIs

A Request for Information (RFI) is issued by the contractor when the contract documents are unclear or insufficient. The architect must respond — typically within a time frame established in the supplementary conditions or the project manual.

The response to an RFI can take several forms:

• A written response (email or formal letter) if the clarification doesn't require a change to the documents
• A Supplemental Instruction if the response involves minor clarification or adjustment with no cost or time impact
• A Contemplated Change Notice if the response reveals a discrepancy that will change cost or time

CHOP Chapter 6.6 notes that some contractors abuse the RFI process by issuing excessive or frivolous RFIs — sometimes to transfer responsibility for decisions to the architect, to imply errors in the documents that don't exist, or to set up future delay claims. The architect must evaluate each RFI on its merits and respond appropriately without overreacting or under-documenting.

Concealed conditions — the 5-day rule

When the contractor encounters conditions that were not visible before construction and that differ materially from what the contract documents indicated, they must give written notice within 5 working days (GC 6.4 of CCDC 2). This triggers the concealed conditions process:

1. Contractor provides notice within 5 working days of discovery
2. Architect investigates and determines whether the condition differs materially from what was anticipated
3. If the condition requires a change, the architect issues a CCN
4. Price and time adjustments are negotiated — Change Order or Change Directive

Quick reference — which document, when

What the ExAC is really testing

Section 4 doesn't test your ability to fill out forms. It tests whether you understand the logic of contract administration: who has authority to do what, in what sequence, and under what conditions. The change management hierarchy — SI → CCN → CO / CD — is the spine of that logic.

When you see a scenario question in Section 4, ask yourself three things:

1. Does this change affect the contract price or contract time? If no — SI. If yes — you need a CCN first.
2. Have the owner and contractor agreed on the price? If yes — Change Order. If no — Change Directive (if the work can't wait) or continue negotiating.
3. Who is signing? SI = architect. CCN = architect. CO = owner + contractor. CD = owner.

Get those three questions right and you'll handle every site instruction and change management scenario the ExAC throws at you.

Frequently asked questions