Extension of Time (EOT) & Delay Impact Calculator

An Extension of Time (EOT) is a formal contractual relief granted to the contractor extending the contractual completion date when project progress is delayed by excusable events beyond the contractor's control.

Excusable delays are caused by employer actions, variations, or neutral events (like extreme weather), granting the contractor time relief. Non-excusable delays are caused by contractor fault or subcontractor defaults, subjecting the contractor to liquidated damages.

Compensable delays entitle the contractor to both an Extension of Time and site prolongation overhead costs (e.g. employer-instructed variations). Time-only delays grant additional completion time but no financial compensation (e.g. exceptionally adverse weather).

Under English and US common law principles (such as the Malmaison approach), when an excusable employer delay overlaps with a non-excusable contractor delay, the contractor is entitled to an Extension of Time (relieving liquidated damages) but is denied prolongation costs for the overlapping period ('time-but-no-money').

FIDIC 1999 Sub-Clause 8.4 entitles the contractor to an EOT for variations, exceptionally adverse climatic conditions, or employer delays. FIDIC 2017 Sub-Clause 8.5 refines weather to 'Unforeseeable having regard to climatic data', adds quantity increases over 10%, and requires strict compliance with Clause 20 claim notices.

In US commercial construction, AIA A201-2017 § 8.3 governs Delays and Extensions of Time, specifying that completion times shall be extended by Change Order for owner delays, fire, unusual transportation delays, or unavoidable casualties.

Approved EOT days shift the target completion date forward. Liquidated damages can only be assessed for net unexcused delay days remaining after subtracting approved EOT days from total gross project delay.

Contractors must submit baseline CPM schedule updates, delay impact analysis (as-planned vs as-built or time impact analysis), site daily records, weather logs, and timely formal written notices per contract requirements.

An EOT is a contractual adjustment moving the formal project completion date outward, excusing the contractor from delay damages for owner-caused or force majeure delays.

Excusable & Compensable delays (owner fault/variations) grant extra time AND cost compensation. Excusable & Non-Compensable delays (neutral events/weather) grant extra time ONLY. Non-Excusable delays (contractor fault) grant neither.

Delays to non-critical tasks absorb available float without delaying overall project completion. An EOT is granted only if the event delays critical path activities.

Contracts (such as FIDIC Clause 20.1) mandate submitting a formal delay notice within a strict window (e.g. 28 days); failure to notify within time bars the EOT claim.

Concurrent delay occurs when two independent delay events—one employer risk and one contractor risk—happen during the same time frame and both affect the critical path.

The SCL Protocol provides internationally recognized best-practice guidelines for analyzing delay, float ownership, concurrency, and EOT entitlement.

Common methodologies include Time Impact Analysis (TIA), As-Planned vs As-Built, Collapsed As-Built, and Impacted As-Planned CPM schedule modeling.

Constructive acceleration occurs when an owner refuses a valid EOT request, forcing the contractor to expend additional resources and overtime to meet the original completion date.

To qualify for an EOT, weather events must exceed statistical 10-year historical averages for that month and location, and directly stall critical exterior work.

A contractor can claim time-related site overhead (site office rental, supervision salaries, equipment rental, utilities) incurred during the approved extended duration.