RFI vs Site Instruction: The Difference on UK Jobs

An RFI asks a question, while a site instruction directs the work. Learn how to distinguish between them to avoid unpaid variations and contractual disputes on UK projects.

By James Shorter ·

RFI vs Site Instruction: The Difference on UK Jobs

Site team reviewing a proposed construction change

An RFI asks for information. A site instruction tells you what to do. That is the whole difference, and most disputes start when the two get mixed up. A question gets answered with a change, nobody calls it a variation, and the cost turns up months later as an argument.

This guide explains what each one is, who can issue them under NEC and JCT, what to do when an RFI answer changes the work, and how to keep a record that holds up. It is written for builders, contractors, subbies and site managers on UK jobs.

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TL;DR

  • An RFI is a question to the designer or contract administrator. A site instruction is a direction from the person with authority under the contract.
  • Only the person named in the contract can instruct. Under NEC that is the Project Manager. Under JCT Minor Works it is the Architect or Contract Administrator.
  • If an RFI answer changes scope, it should be followed by a proper instruction. If it only clarifies, it does not need one.
  • Email can be enough in writing, but a verbal instruction to change scope should not be acted on until it is confirmed in writing.
  • Log both against the same project, with dates, names and drawing revisions, so the cost trail is there when you need it.

Table of Contents

What an RFI is

A request for information is a project communication used to ask a designer, consultant or contract administrator to clarify or supply information needed to carry out the works. LexisNexis describes it in those terms in its UK legal glossary.

On site, “raising an RFI” means writing the question down formally, sending it to the right person and waiting for a written answer. Typical examples:

  • The architect’s drawing shows a 100mm stud wall, the structural drawing shows a 150mm block wall. Which is right?
  • The spec calls for a product that is no longer made. What is the approved alternative?
  • A beam on the drawing clashes with a duct run. Which gives way?

The key point is that an RFI is a question. It does not change the contract, the price or the programme by itself. It exists so you can build the right thing first time.

Not every email with a question mark is an RFI. A proper RFI has a number, a date, a clear question, the drawing or spec reference, who it is addressed to and the date you need an answer by. If you want a ready format, our UK construction RFI template covers the fields.

What a site instruction is

A site instruction is a direction to the contractor to do something: carry out extra work, omit work, change a specification, open up for inspection, or proceed in a particular way. It comes from the person the contract authorises, and it can change scope, cost and time.

The label varies by contract:

  • Architect’s Instruction (AI) or Contract Administrator’s Instruction (CAI) under JCT.
  • Project Manager’s Instruction under NEC.
  • “Site instruction” as the general site term, often for smaller jobs with no formal contract administrator.

A usable instruction should identify the change, say what is to be done, carry a date and state how it will be valued. If any of those is missing, ask before you start. Pricing after the work is built is the position you do not want to be in.

RFI vs site instruction: side by side

RFI Site instruction
Purpose Ask for missing or conflicting information Direct the contractor to do, change or omit work
Who sends it Usually the contractor or subcontractor The person authorised under the contract
Who answers or issues Designer, consultant or contract administrator Project Manager, Architect or Contract Administrator
Timing Before the work is built Before or during the work
Effect on contract None on its own Can change scope, cost and programme
Does it justify extra payment? Not by itself Often, if it changes scope
Typical record RFI log with number, dates, response Instruction register and variation log

The row that matters most is the contractual effect. An RFI is a practical tool. Under NEC, RFIs and technical queries are practical systems for finding the information needed to progress work, but are not referenced in the contract, according to CECA’s NEC4 bulletin. A site instruction is a contract mechanism.

Who is allowed to issue a site instruction

This is where jobs go wrong. The client says “can you move that wall?” on a walkabout. The clerk of works mentions a different finish. The architect’s assistant emails a sketch. Which of those is an instruction?

The answer comes from the contract, not the job title. RICS guidance makes the point that the authority to instruct derives from the contract’s terms rather than the title of the individual, so setting out who can issue valid instructions is a key project set-up task.

NEC contracts

Under NEC, the Project Manager is the only person contractually able to issue an instruction changing the original Scope, unless that power has been delegated. Check whether a delegation has been made and to whom, and get it in writing.

JCT contracts

Under the JCT Minor Works Building Contract 2011, only the Architect or Contract Administrator can issue instructions to the contractor, and the employer is not entitled to instruct the contractor directly. Other JCT forms have their own wording, so read the one you are on.

Practical rule for site

Before you act on anything that changes the work, ask three questions:

  1. Who sent it, and are they named in the contract as able to instruct?
  2. Is it in writing, with a date?
  3. Does it say how the change will be valued, or at least that it will be?

If the answer to any is no, send a short written confirmation back and wait for a reply.

When an RFI answer turns into a variation

Most RFI answers are plain clarifications. “Use the 150mm block wall, as per the structural drawing.” You build what was already in the contract. No change, no cost.

Some answers are different. “Use the 150mm block wall and add a steel lintel over the new opening.” Now the answer adds something that was not in the original scope. The CECA bulletin on RFIs says that a response that changes Scope should be issued separately as a Project Manager Instruction, while a clarification does not need one.

The same logic applies on JCT and on smaller jobs. If an RFI reply changes what you price, flag it straight away and ask for a formal instruction. Do not treat the reply as the instruction unless the person replying has the authority and the reply says so.

What NEC says about cost and time

Under NEC, an instruction changing the Scope is a compensation event. The exceptions are an instruction to accept a defect, to change Contractor-provided Scope at the Contractor’s request, or to comply with the Client’s Scope. Where additional work is instructed and notified as a compensation event, the contractor must proceed while following the quotation process.

Also under NEC, an RFI or technical query that becomes urgent or could affect time or cost should be notified as an early warning. So an overdue RFI is not just an irritation. It can be a contractual notice you need to serve.

NEC and JCT notice periods differ, so check your own form for the time limits. Our guide to RFI response times under NEC and JCT goes through what turnaround to expect.

Do emails, WhatsApp messages and verbal requests count?

This is the question that comes up most on small and mid-size jobs, where half the decisions are made on a phone.

Under NEC, instructions must be in a form that can be read, copied and recorded, and an email may suffice. The same bulletin says a verbal instruction to change the Scope should not be followed until the Project Manager confirms it in writing.

In practice:

  • A verbal “just do it” from the client, architect or site manager is not something to price on. Confirm it in writing the same day.
  • A message thread can be evidence of what was said, but only if you can find it later. Scattered chats make that hard.
  • A message from someone without authority may still be a request you need to answer, but it is not an instruction.

The habit that protects you is simple. When a decision is made verbally or by message, write it up as “Further to our conversation today, I understand you want X. Please confirm this is an instruction and how it will be valued.” Send it to the person with authority.

A worked example

You are building a rear extension under a JCT Minor Works contract. The architect is the Contract Administrator.

Day 1. Your groundworker spots that the drawing shows the drain run 1.2m from the new foundation, but the survey shows a manhole closer. You raise RFI 014: “Drain position conflicts with foundation setting out. Please confirm foundation depth or drain diversion. Drawings A-102 rev C and S-004 rev B. Response needed in 5 working days.”

Day 3. The architect replies: “Deepen the foundation locally to 1.5m. See sketch.” This is an answer to your question, but it adds work: extra excavation and concrete.

Day 3, same afternoon. You do not just start digging. You reply: “Thanks for RFI 014. This adds work not in the original scope. Please issue a Contract Administrator’s Instruction so we can price it.” The instruction arrives on day 4, with the valuation basis. Your log now shows RFI 014, the instruction number, the variation and its value, all connected.

Worked example from RFI to formal instruction

Without that step, the same job ends with a foundation built to a sketch, no instruction, and a disagreement at final account about whether the extra was ever agreed.

How to raise, answer and record an RFI

The checked contract sources above cover who can instruct. For the RFI itself, the discipline is mostly about clarity and record-keeping. A workable process:

  1. Check first. Look at the latest drawing revisions and spec before asking. An RFI that the documents already answer wastes everyone’s time.
  2. Write one question per RFI. Mixed questions get partial answers.
  3. Give the references. Drawing number and revision, spec clause, location on site, a photo or marked-up sketch.
  4. Address it to the right person. The designer or contract administrator named in the contract, not whoever is easiest to reach.
  5. State the date you need a reply by, and what it will hold up if it is late.
  6. Log it. Number, date sent, who to, date due, date answered.
  7. Decide what the answer is. Clarification, or a change? If it is a change, ask for an instruction.
  8. Close it out. Link the answer to the drawing revision and the instruction or variation, if there is one.

Our post on RFI vs submittal covers another pair people confuse, and drawing version control explains how to keep the revision trail clean so every RFI points at the right drawing.

Perspective: where the paperwork actually breaks

We built BRCKS because we have seen how this plays out on real jobs. The contract documents are rarely the problem. The problem is that the question is asked in a WhatsApp group, answered by phone, acted on by a subbie the next morning, and priced by nobody.

The RFI and the instruction are two different documents because they do two different jobs. When teams treat a chat message as both, they lose the paper trail at the moment it matters: the final account.

Perspective: where the paperwork actually breaks — overview diagram

Our view is that site teams should not have to change how they talk. People will keep messaging, and that is fine. What has to change is what happens afterwards. Every question, answer, instruction and variation should end up filed against the right project, in order, with dates. That is what we have designed BRCKS to do, including capturing project messages from WhatsApp through a dedicated business number, so the decision trail builds as you work rather than being rebuilt later from memory.

The practical test we use: could you hand your project record to a quantity surveyor today and have them follow every change from question to instruction to cost without ringing you? If not, that is the gap to close.

— James

Keeping RFIs and instructions in one record

If you want RFIs, site instructions and variations linked rather than scattered across inboxes and phones, BRCKS for builders tracks RFIs with audit trails, logs variations in a structured way and files photos, drawings and decisions against the right project. Subcontractors and clients join free, so the people who raise questions and receive instructions are in the same place.

BRCKS is £40 per seat per month, billed annually, with a 14-day free trial. See the pricing page for the detail. The plain-English search across project history is built for moments like this: type the RFI number or the drawing and see everything connected to it, which we find saves site teams 30+ minutes a day.

Common mistakes to avoid

  • Treating an RFI reply as an instruction. Unless it comes from the authorised person and says it is an instruction, it is an answer.
  • Starting work on a verbal go-ahead. Confirm it in writing first, as the NEC guidance above advises for scope changes.
  • Taking instructions from the wrong person. A client on site is not automatically able to instruct under a JCT contract.
  • Letting RFIs sit. An unanswered question that affects time or cost can need an early warning under NEC.
  • Pricing late. Raise the cost impact when the instruction arrives, not at final account.
  • Losing the revision. An answer that refers to a superseded drawing causes the next RFI.
  • Using email only for everything. Email can be valid, but without a number and log, nobody can see what is open.

FAQ

Is an RFI the same as a site instruction?

No. An RFI is a question asking for clarification or missing information. A site instruction is a direction from the person authorised under the contract to do, change or omit work. An RFI answer can lead to an instruction if it changes the scope.

Can I get paid for work done after an RFI response?

Only if the response is an instruction, or is followed by one, that changes the scope and your contract provides for valuing it. A clarification of work already in your price does not usually carry extra payment. If the answer adds work, ask for a formal instruction before you start and state that you will price it.

Who can issue a site instruction on a UK job?

The person named in your contract. Under NEC that is the Project Manager unless they have delegated the power. Under the JCT Minor Works Building Contract 2011, it is the Architect or Contract Administrator, and the employer cannot instruct the contractor directly.

Is a WhatsApp message a valid instruction?

Under NEC, instructions need to be in a form that can be read, copied and recorded, and an email may suffice. A message from someone without authority is not an instruction, and a verbal or informal scope change should be confirmed in writing by the person who can instruct. Check your own contract wording and take advice if the value is significant.

What does “raise an RFI” mean?

It means formally submitting a written question to the designer or contract administrator, usually with a number, date, references and a required response date, then logging it until it is answered.

Sources

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How BRCKS Can Help

Distinguishing between RFIs and Site Instructions is vital for maintaining a clear audit trail and avoiding costly delays on UK projects. BRCKS simplifies this process by providing a centralised platform where teams can issue, track, and resolve these documents with full transparency. By digitising your site communications, you ensure that every instruction is recorded and every query is answered promptly. Explore how BRCKS can streamline your project management and keep your site moving forward today. Learn more at BRCKS and explore our full feature set.


Sources

Record, price and get sign-off on changes with variation management in BRCKS.