A delay that isn't notified is a delay you'll pay for. Here's how to identify delay events, notify properly, and build EOT claims that actually succeed.
Every project runs late. That's not cynicism, it's thirty years of observation. The question isn't whether delays will happen — it's whether you'll recover the time and cost when they do.
Extension of time claims are where small contractors consistently leave money on the table. Not because the entitlement isn't there, but because the notifications are late, the records are thin, and by the time the final account comes around, the contractor's QS is trying to reconstruct a delay narrative from memory and a few emails.
An EOT moves the contractual completion date. That matters for one very specific reason: liquidated damages. If the contract says you'll finish on 15 March and you finish on 30 March, the employer can deduct LDs for those 15 days. But if you've been granted a 15-day extension, the completion date moves to 30 March and no LDs apply.
That's the core of it. An EOT doesn't give you money directly — it protects you from having money taken away. The financial recovery for delay-related costs (prolongation, disruption, loss and expense) is a separate claim, though the two are closely linked.
Under JCT contracts, you can only claim an extension of time for "relevant events" listed in the contract. The most common ones for small contractor projects:
Variations. Any instruction that changes the works can affect the programme. An architect's instruction to add scope, change materials, or alter the sequence is a relevant event if it delays completion.
Late information. If you need design information to proceed and it arrives late, that's a relevant event. The key is proving you actually needed it when you said you did — which means your information required schedule needs to be realistic and issued early enough.
Employer's persons. Other contractors employed directly by the client, or the client's own team, causing delay. On multi-contractor sites, this comes up constantly — the employer's fit-out contractor hasn't cleared the area you need access to.
Exceptionally adverse weather. This doesn't mean any rain. It means weather that's significantly worse than what you'd reasonably expect for the time of year and location. Met Office data is your friend here — compare actual conditions against historical averages for your site location.
Force majeure and statutory powers. Less common but they happen. COVID taught everyone about force majeure whether they wanted the lesson or not.
Here's where most claims fail. JCT requires the contractor to give notice of delay "forthwith" — meaning as soon as you become aware that a relevant event is likely to cause delay. Not when the delay has happened. Not at the end of the month. Forthwith.
The notice should state:
Keep it factual and short. You're not writing the full claim at this stage — you're putting the contract administrator on notice that a delay has occurred and you're going to claim time.
I've seen contractors lose six-figure EOT claims because the first written notification arrived three months after the delay event. The contract administrator's response is predictable: "If it was causing you delay, why didn't you tell us at the time?"
Once you've notified, you need to build the substance:
Programme analysis. Show how the delay event affected the critical path. This doesn't need to be a full forensic delay analysis with Primavera P6 — for most small contractor projects, a simple impacted as-planned analysis is sufficient. Take your baseline programme, show where the delay event sits, and demonstrate how it pushed the completion date.
Records. Your site diary is critical. Daily records showing what work was planned, what was actually done, and what couldn't proceed because of the delay. If the delay was due to late information, show the RFI dates, the expected response dates, and the actual response dates. If it was weather, show Met Office data alongside your daily records.
Causation. You need to demonstrate the link between the relevant event and the delay to completion. This is where many claims fall apart — the delay event might have genuinely happened, but if it wasn't on the critical path, it didn't delay completion. Be honest about this. Claiming time for a delay to a non-critical activity damages your credibility on the claims that are genuine.
Quantification. State how many days or weeks the delay event pushed completion. Be specific. "Approximately 3-4 weeks" is weak. "17 working days, calculated as follows..." is strong.
Not notifying at all. The biggest one. Some contractors treat EOT claims as something you deal with at the end of the job. By then, your leverage is gone and your records are stale.
Over-claiming. Claiming 12 weeks of extension when the actual critical delay was 4 weeks. This happens when contractors try to dump every problem into a single claim. It's transparent, it annoys the contract administrator, and it undermines your genuine entitlements.
Ignoring concurrent delay. If your own works are also in delay at the same time as the employer's delay event, the position is more complicated. Under JCT, concurrent delay generally still entitles you to the extension (but not the prolongation costs). Pretending your own delays don't exist is a quick way to lose credibility.
No programme baseline. If you never issued a proper baseline programme, proving that anything delayed completion becomes much harder. Invest the time at the start of every project to produce a realistic, agreed programme. It's your measuring stick for the rest of the job.
An extension of time protects you from LDs. But if the delay means you're on site longer, you're incurring costs — site management, temporary accommodation, welfare facilities, scaffold hire, plant standing time, insurance. These are prolongation costs, and they're claimed separately under the loss and expense provisions.
The calculation is straightforward in principle: take your time-related preliminaries cost per week, multiply by the number of weeks of employer-caused delay. In practice, there's often argument about which costs are genuinely time-related and what the correct weekly rate is. Keep your preliminaries build-up from the tender — it's the starting point for any prolongation calculation.
EOT management is really about three things: early notification, good records, and honest assessment. Notify the moment you see a delay developing. Record what's happening every day in your site diary. And be honest about which delays are the employer's problem and which are yours.
At Construction AI, delay tracking is built into the financial module's contract administration tools — linking delay events to programme activities, tracking notifications, and building the record trail that supports your claim. But the fundamentals don't change whether you're using software or a filing cabinet: notify early, record everything, and don't wait until the final account to raise it.
Stephen Mckenna MCIOB
30+ years in UK commercial construction, from site management to director level. Now building the project management tools he wished he'd had.
Tier-one contractor processes shouldn't only be available to tier-one contractors. Drawing registers, document control, RFIs, programmes, financial tracking — built for how you actually run projects, priced so any construction business can access them. Get started today.
By subscribing, you agree to our Privacy Policy.
NEC4 is gaining ground where JCT has dominated. Here's what's actually different, when each contract framework makes sense, and what your software must handle.
Practical completion triggers half your contract obligations. Here's what it actually means, the common arguments, and how to manage the process properly.
Choosing the wrong JCT contract costs thousands. A practical guide to when Minor Works is right, when you need Intermediate, and the grey area in between.
Tier-one processes, priced for any size business. Get started today.