Delay costs | Chalkline

TL;DR

Delay costs are the additional time-related expenses a builder incurs when a delay is caused by the principal: extended site overheads, supervision, idle plant, and escalated material prices. Getting an extension of time (EOT) does NOT automatically give you money; the EOT only stops liquidated damages (LDs) from running. To recover costs you need a separate contractual mechanism (a delay costs or delay damages clause) AND the delay must be a compensable cause, typically a principal-caused event such as a variation, late information, or late principal-supplied items. Weather and force majeure are usually time-only: you get the days, not the dollars. Price a daily delay-cost rate into your contract schedule before you sign, and keep contemporaneous records from the first day a qualifying event arises.

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What delay costs are

Delay costs (also called prolongation costs) are the site-running expenses that keep accumulating during a period of delay the builder did not cause. They are time-related costs: the costs go up with every extra day on site.

Common categories (verified 2026-06-11 against Chamberlains Law Firm, Delay Costs, Delay Damages and the Prevention Principle and Muscat Tanzer, Delay, Disruption and Prolongation Claims):

Extended preliminaries: site shed, portable toilets, hoarding, scaffold retention, scaffolding hire
Site overheads: project manager and site supervisor time, security, utilities, temporary services
Idle plant and equipment: crane hire, concrete pump, formwork on-hire, other plant that cannot be stood down
Extended labour: tradespeople held on-site in a standby capacity or forced to re-mobilise
Escalation: where the delay pushes work into a higher-cost period (price rises in materials or labour, usually relevant on longer commercial projects)

On a residential job the biggest delay-cost items are typically extended supervision, subcontractor re-mobilisation fees, and extended site shed and toilet hire. On a commercial job, idle plant and escalation can dwarf the rest.

The two conditions: delay event plus a cost mechanism

A builder cannot recover delay costs from entitlement to an EOT alone. Two things must both be present:

A qualifying delay event that falls within the contract’s list of compensable causes (see delay event).
A contractual mechanism that expressly entitles the builder to recover costs, not just time, when that event occurs.

Without both, the builder gets extra time (the EOT) but absorbs the costs internally.

The EOT-without-costs trap

This is the most common financial misunderstanding in residential and mid-tier commercial building.

An EOT adjusts the contract’s completion date. It stops LDs from running during the extension. It does not, by itself, entitle the builder to any money. The builder is simply protected from the penalty; they are not compensated for the cost of being held up (verified 2026-06-11 against Contracts Specialist, Extension of Time in Building Contracts).

The split between time and costs runs along the line of who caused the delay:

Delay cause	EOT entitlement	Cost entitlement
Principal variation or instruction	Yes (compensable)	Yes, where the contract has a delay costs clause
Late principal-supplied information or PC items	Yes (compensable)	Yes, where the contract has a delay costs clause
Latent conditions (rock, contaminated ground)	Yes (compensable in most contracts)	Yes, where the contract has a delay costs clause
Adverse weather above contract threshold	Yes (non-compensable in most residential contracts)	No
Force majeure, industry shutdown	Yes (non-compensable in most residential contracts)	No
Concurrent delay (both parties contributed)	Depends on the contract	Usually no, or reduced

HIA contracts. Clause 19.4 of the HIA residential contract creates an express entitlement to delay damages when the delay is caused by “an act, default, or omission of the owner.” The builder may claim the actual increase in cost to carry out the works, plus the builder’s margin applied to that cost. Common recoverable costs include increased material prices, trades and labour, and equipment hire (verified 2026-06-11 against Contracts Specialist, Clause 19.4 HIA Delay Damages). Weather and force majeure grounds that entitle only an EOT under Clause 19.1 do not activate Clause 19.4: those are time-only delays.

MBA and AS 4000 contracts. Commercial contract suites (AS 4000, AS 2124) typically include a separate clause entitling the contractor to recovery of time-related costs for principal-caused delays, in addition to the EOT. MBA residential contracts follow a broadly similar structure to HIA on compensable vs non-compensable causes, though the specific clause references differ by state contract edition.

No delay costs clause. If the contract contains no delay costs clause, the builder’s only avenue to recover costs for a principal-caused delay is damages for breach of contract at common law, which requires proving the delay amounted to a breach and quantifying the loss. That is a harder and slower path than a contractual claim.

VIC SOP Act: delay costs now claimable (post April 2026)

Before 15 April 2026, Victoria’s SOP Act had an “excluded amounts” regime (sections 10A and 10B) that prevented builders from including delay damages in statutory payment claims. Those costs had to be pursued through court, not adjudication.

From 15 April 2026, sections 10A and 10B were repealed. Delay costs are now claimable through the VIC SOP fast-track adjudication path, just as they have always been claimable in NSW and Queensland (verified 2026-06-11 against the excluded amounts article and the VIC SOP guide). This is the most significant practical change for Victorian builders with unresolved delay cost claims.

Pricing delay costs into the contract

The time to address delay costs is before you sign, not after a delay arises.

Include a delay cost schedule (sometimes called a preliminary cost schedule or daily rate schedule) in the contract. State the daily or weekly cost of extended preliminaries so the rate is pre-agreed and no argument is needed at claim time.
Check the compensable-cause list. If a likely risk (e.g. late CC approval, late owner decision on selections) is not listed as a compensable cause in the contract, it will produce time-only relief at best.
Negotiate a delay costs clause if none exists. A lump-sum or fixed-price contract with an LDs clause but no matching delay costs clause is commercially one-sided: the owner is protected from late completion but the builder carries the cost of any delay the owner causes.

Keeping records

Contemporaneous records are what convert an entitlement into a paid claim. From the first day a qualifying delay event arises, capture (verified 2026-06-11 against Muscat Tanzer, Delay, Disruption and Prolongation Claims):

Daily site diary entries noting the delay cause and what could not proceed
Receipts and invoices for every cost line affected (plant hire, sub fees, supervision timesheets)
Correspondence with the principal documenting the cause and your notice of the event
Programme updates showing the critical path impact

The final account is where delay cost claims land. If the records are not there by that point, the claim is unsupported and will not be paid.

What can go wrong

Claiming costs on a time-only EOT ground. If the contract specifies weather as a non-compensable cause, submitting a delay costs claim against a weather EOT will fail and may damage your credibility on other claims.
No contemporaneous records. Reconstructing costs after the fact is possible but much harder to substantiate and easier to dispute.
Missing the notice window. Most contracts require notice of the delay event (and separately, notice of the intention to claim costs) within a fixed period. Missing either can forfeit the entitlement.
Unsigned variations carrying hidden delay costs. If the owner instructs a variation that delays the programme, and the variation instruction is not followed by a formal EOT notice, the delay costs will be hard to separate from other project costs.
Concurrent delay. Where both the principal and the builder contributed to a delay at the same time, most contracts deny or apportion the cost recovery. This is a fact-intensive dispute and often requires expert programme analysis (verified 2026-06-11 against Norton Rose Fulbright, Time is ticking).

References

Chamberlains Law Firm: Delay Costs, Delay Damages and the Prevention Principle (verified 2026-06-11)
Contracts Specialist: Clause 19.4 HIA Contract, Delay Damages (verified 2026-06-11)
Contracts Specialist: Extension of Time in Building Contracts (verified 2026-06-11)
Muscat Tanzer: Delay, Disruption and Prolongation Claims (verified 2026-06-11)
Norton Rose Fulbright: Time is ticking, managing delay and EOT in construction contracts (verified 2026-06-11)