by Dr. Franco Mastrandrea

Purpose

This note addresses the concept of float in construction scheduling, being the amount of delay an activity can absorb without adversely impacting subsequent activities or the project completion date. It outlines different types of float (total, independent, free, and interfering) and emphasises its significance when assessing localised delays, costs, and contractor resource planning.

It examines the contentious issue of float ownership in relation to a traditional construction contract, noting that courts and industry guidance differ on whether float belongs to the contractor, the employer, or the project. The note proposes a distinction between original float (in the contractor’s programme) and emergent float (arising from planning errors, neutral events, or party-caused delays leading to project delays).

Understanding who may legitimately consume float is central to assessing both entitlement to time and financial recovery.

The contractor is here generally regarded as entitled to original float, while emergent float belongs to the party whose actions created it, with neutral-event float belonging to the project.

Examples illustrate how float may change as the critical path shifts and how parties may benefit from the float that arises during project delivery.

Understanding Float: Types and Terminology

A critical activity is one with no float. Activities with float are non – or sub-critical. Some activities may be critical for only part of their full duration. For example, the steel frame for a building may be critical up to the point when the roofing, cladding, or first‑fix MEP works can begin; it may be sub‑critical before or after that period.

Float takes various forms:

• total float: being the total time by which one (or more) sub‑critical activities may be delayed before causing delay to subsequent activities and to project or milestone completion dates. Total float is thus not a measure of flexibility within individual activities, but is often a key project-wide measure.
• activity (independent) float: being the difference between the early start and late start dates, or the early and late finish dates, of any sub‑critical activity.
• free float: being the amount of time a sub‑critical activity can consume without affecting the early start of a subsequent activity.
• interfering float: being the difference between total float and free float – a measure of the extent to which free float in a particular activity can be consumed without interfering with subsequent activities.

The critical path is dynamic and may shift, even frequently.^[1] Float may also emerge (reduce or disappear) as a result of such shift(s).

Float is also significant when considering localised delays, yet it is often overlooked by delay analysts and disputing parties.[^2]

Deferral

Where a sub‑critical activity is deferred in its start or performance, project completion may not be delayed, even if the entire float is consumed.^[3] However, the contractor may still incur additional costs, such as:

• where the duration of the activity once started remains as planned;^[4] or
• where the deferral impacts on the contractor’s planned deployment of resources.^[5]

Prolongation

Conversely, if an activity begins on its planned early start date and finishes no later than its planned late finish date, there will be no delay to project completion^[6] (and normally no need for an extension of project time), because the float consumed does not impinge on the start of the next planned activity.

However, the contractor may still incur additional time-sensitive costs, because the activity may have been prolonged, consuming independent float and, unless the contractor has reduced its resources, associated time-sensitive costs., such as localised management and supervision, and dedicated plant.

In this context, a localised delay claim, in which activity specific time-sensitive costs may be more easily identified and quantified, may yield a more favourable outcome than including such costs in a more precarious disruption claim.

Traditional Approaches to Float “Ownership”

The question of float ownership is often contentious. Tribunals have variously held that:

• the contractor owns the float,^[7] meaning, for example, that the employer is not entitled to use float to accommodate changes;^[8]

• the employer owns the float, on the basis that it has paid for a project that includes float and, unless the critical path is adversely impacted, the contractor can have no complaint. The challenge with that argument is that, as noted, localised deferral or prolongation caused by the employer are likely to come at additional cost to the contractor;
• float belongs to the project, meaning whichever party reaches the float first is entitled to consume it.^[9]

Limitations of Binary Ownership Models

I have suggested elsewhere that making everything turn on either “ownership” or critical path impact is neither adequate nor helpful.

Contracts sometimes make provision for float ownership. The SCL Protocol, for example, notes:^[10]

“The ‘ownership’ of float causes particular arguments in disputes over entitlement to an EOT. A Contractor may argue that it ‘owns’ the float, because, in planning how it proposes to carry out the works, it has allowed additional or float time to give itself some flexibility in the event that it is not able to carry out the works as quickly as it planned. If, therefore, there is any delay to the Contractor’s progress for which the Contractor is not responsible, it may contend that it is entitled to an EOT, even if the delay to progress will not result in the contract completion date being missed, but merely in erosion of its float. On the other hand, an Employer may typically say that the Contractor has no EOT entitlement unless the delay to progress will result in a contract completion date being missed. So (the Employer may say) the project owns the float.”

It asserts that the parties “should ensure that this issue is addressed in their contracts”. However, prescribing exclusive float ownership may be a dubious directive given the dynamic nature of an unfolding project.^[11]

A New Framework: Original vs. Emergent Float

A distinction between original float, and what I label ‘emergent’ float is considered appropriate.

Original Float

Original float refers to float built into the plan for the original works.[^12]

Experience (consistent with reviews of contractors’ scheduling of works) suggests that a sounder presumption may be appropriate. The contractor will typically have planned and priced the original works based on its optimal use (including levelling) of labour and plant resources, including allowances for the contractor’s risk items and performance contingency. Replanning of that original work because of errors or inadequacies in that original scheduling, provided no project delay arises from any such replanning, may result in the erosion of float. On this basis, original float belongs to the contractor, because the contractor embeds float into its planned sequencing and risk allowances.

Emergent Float: Allocation Based on Causation

Emergent float can arise from:

• correction of errors or inadequacies in the contractor’s original planning;
• neutral post-contract events; and/or
• post-contract events arising from either party’s acts, omissions or defaults

that generate project delay.

Pausing there and taking stock – subject always to the express contract terms,^[13] the following general rules are offered:

• the contractor “owns” and may take advantage of any original float.
• the creator of emergent float “owns”, and may take advantage of, that float.
• where emergent float arises from neutral events, it belongs to the project.

Application of the Framework: Case Categories

As already proposed, where float is generated during the execution phase as a result of acts omissions or default of the parties, the responsible party should be entitled to take advantage of the float created.

Employer-Caused Emergent Float

Thus, if the employer causes critical delay by, for example:

• ordering additional works falling on the critical path, or
• providing design information late,

then the employer may consume any emergent float generated in other activities by ordering varied work, or by deferring the provision of information in relation to the activities in that float, without incurring additional project-wide prolongation costs.[^14]

Where the employer’s breach generates critical delay, additional and less obvious advantages may accrue.^[15]

Contractor-Caused Emergent Float

Conversely, where emergent float is generated by the contractor’s correction of errors in original planning or by acts omissions or defaults in performance, the contractor may consume that float, and not be deprived of it by the employer whether by ordering variations or otherwise, albeit while still being exposed to payment of delay damages to the employer by reason of the resulting project overrun.

Neutral-Event Emergent Float

Where emergent float is generated by neutral events:

• and critical delay which is project-wide – such as exceptional weather – is suffered, opportunities to exploit float may be limited, as work in other activities may equally be adversely impacted by that weather. Exceptions may include internal or other activities in float which are non-weather sensitive, such as design or administrative tasks.
• and critical delay is suffered which is activity specific – such as a steelworkers’ strike – opportunities may arise in other unaffected activities in emergent float.

About the author

Dr. Franco Mastrandrea is a Chartered Quantity Surveyor and Chartered Arbitrator with over 40 years of experience in the construction industry. He has acted as expert on more than 50 international project management, delay and quantum-related disputes.

From London to Australia and Canada to Antarctica, Franco has extensive and diverse dispute resolution expertise. With an established record in drafting, interpreting and applying commercial terms in contracts, he successfully combines both knowledge and experience under traditional cross-examination and hot-tubbing.

Franco’s expert commissions cover a wide range of industries including oil and gas in Australia, Canada, Kazakhstan, North Africa and South East Asia; transport infrastructure in the Caribbean and the UK; power generation, from CCGT to windfarms, in the UK; and numerous building and infrastructure projects around the world.

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References

[1] Thus, in Fortec Constructors et al v. United States 8 Cl. Ct. 490 (1985), Yock J said for the US Court of Claims at [106]:

‘Indeed, Mr. Cook acknowledged that delay encountered in completion of a non-critical item may make that item critical so that ‘every month, conceivably, the critical path would change’, which is precisely what happened in the instant case.’

Cf. Dependable Mechanical Systems Inc. v. Four Seasons Site Development Ltd.
2019 ONSC 5798, at [18]:

‘Critical path on a project can change month-to-month… Scheduled work that was not previously on the critical path may become critical path work as a result of other project delays.’

[2] For a more detailed review of such delays, see Mastrandrea, F, “Localised Delays: The Poor Relation in Construction Claims Appraisals?”, [2023] ICLR 112.

[3] Unless, in conjunction with loss of float in other activities, shared or total float is exceeded. For the sorts of complications that can arise where the deferral does impact the critical path, consider Bacal Construction (Midlands) Ltd. v. Northampton Development Corp. (1975) 8 BLR 91, CA, in which the design/build contractor for 518 dwellings priced for a 65 week contract period with handover of dwellings to the employer to begin in week 43. The employer wanted handover of completed dwellings to begin earlier, from week 34, to which the contractor agreed, subject to closure of a lane before the work started. In the event, the lane closure was not achieved for some 26 weeks – too late to allow the 34 weeks’ programme to be achieved, a failure attributed to the employer. On a dispute over the meaning of a letter thereafter insisted on by the contractor providing for the recovery by the contractor of abortive expenditure, the Court of Appeal held that such expenditure included that resulting from the disruption of the 34 week programme due to the delayed closure of the lane – which would not have been incurred if the contractor had throughout followed its original 43 week programme, and expenditure in any overrun of the overall 65 week period had the original 43 week programme been followed.

[4] Additional costs might include re-planning, prolonged storage of materials and/or goods, escalation in prices for labour plant or materials, standing time for commissioned resources such as labour or plant which have no alternative work to go to, loss of contribution to overheads, additional borrowing, etc.

[5] Additional costs might include re-planning, learning curve effects through the need to introduce additional “green” resources, and efficiency losses through congestion.

[6] Subject to the same proviso on shared or total float being exceeded.

[7] See, for example, Weaver-Bailey Contractors, Inc. v. United States 19 Cl. Ct. 474 (1990) providing, at page 481, the following example:

‘Suppose that as part of the job, the contractor promised to build a fence along two edges of the property, and that building the fence will take 20 days. No other work depends on the completion of the fence, so delaying work on the fence until December 11, 1989 will not put the contractor in danger of late completion. In other words, building the fence is an activity with a lot of float time. However, float time is never unlimited. If on December 20 the contractor has yet to begin the fence, or if there is more than 11 days’ worth of fencing work to be done as of December 20, then the contractor will not finish the job on time.… Consider now the effect on our hypothetical contractor if on December 1, before fencing work had begun, the buyer of the house told the contractor that he would like all four sides of the property to be fenced, thereby doubling the fencing work. Clearly the contractor could not complete the entire project by the end of the year, but through no fault of his own.…’

In England, the matter appears first to have been explicitly addressed in Ascon Contracting Ltd. v. Alfred McAlpine Construction Isle of Man Ltd. (1999) 66 Con. LR 119, (2000) 16 Const. L.J. 316, in which HH Judge John Hicks, QC, held in relation to a sub-contract dispute that the contractor was entitled to the main contract float:

‘[91].…It does not seem to be in dispute that McAlpine’s programme contained a “float” of five weeks in the sense, as I understand it, that had the work started on time, and had all sub-programmes for sub-contract works and for elements to be carried out by McAlpine’s own labour been fulfilled without slippage the main contract would have been completed five weeks early. McAlpine’s argument seems to be that it is entitled to the “benefit” or “value” of this float….

[92] … The float is certainly of value to the main contractor in the sense that delays of up to that total amount, however caused, can be accommodated without involving him in liability for liquidated damages to the employer or, if he calculates his own prolongation costs from the contractual completion date (as McAlpine has here) rather than from the earlier date which might have been achieved, in any such costs.’.

[8]See, for example, Natkin & Co. v. George A. Fuller Co. and another 347 F.Supp. 17 (1972) for a finding of fact to that effect: ‘R… Neither total nor free float is to be used for changes.’

Cf. Commissioners of the State Bank of Victoria v. Costain Australia Ltd [1982] Vic SC 431, (1983) 5 BCLRS 193, in which Gobbo J in the Supreme Court of Victoria said:

‘The given facts did not indicate whether the delayed activity was critical. The extra work could be completed contemporaneously with the other works remaining to be completed. In those circumstances it could not be said that the given facts necessarily established that the variation had an effect upon the time required to complete… Another situation which is similar… is that where the builder has, by careful management, husbanded some saving in time. In that situation the builder should not be deprived of the benefit of such saving. Where an architect, with the benefit of knowledge of all the actual circumstances, makes a fair and reasonable extension, it seems unlikely that he would be able, in effect, to deprive the builder of the benefit of this saving by allocating it only to the extra work.’

[9] See, for example, the AACE International Recommended Practice No. 29R-03 for Forensic Schedule Analysis (RP 29R-03), 2011, Section 1.5 Underlying Fundamentals and General Principles B General Principles 3:

‘In the absence of contrary contractual language, network float, as opposed to project float, is a shared commodity between the owner and the contractor. In such a case float must be shared in the interest of the project rather than to the sole benefit of one of the parties to the contract.’

[10] Second Edition, 2017, Guidance Part B, paragraph 8.2.

[11] One of the potentially unanticipated consequences is immediately pointed to, at Guidance Part B, paragraph 8.3:

‘… Under contracts where the Employer Delay has to affect the contract completion date, if an Employer Delay occurs first and uses up all the total float, then the Contractor can find itself in delay and paying liquidated damages as a result of a subsequent Contractor Delay which would not have been critical if the Employer Delay had not occurred first. Under contracts where the Employer Delay only has to affect the Contractor’s planned completion date, the Contractor is potentially entitled to an EOT every time the Employer or CA delays any of its activities, irrespective of their criticality to meeting the contract completion date. Under the type of contract that is silent or ambiguous about float, uncertainty exists and disputes are likely to follow.’

[12] Whether the original programme was viable – a matter often unexplored by delay analysts – may be a separate consideration, beyond the scope of this article.

[13] See, for example, Lexicon, Inc. v. Icon Construction, Inc. 2009 WL 722715, in which a subcontract provided:

 ‘All float or slack time is for the exclusive use or benefit of (the Contractor and specified others),’ but not the sub-contractor.

One may wonder why a well-informed contracting party (here the sub-contractor) would willingly enter into such a one-sided arrangement.

[14] It is assumed here that the contractor will typically be entitled to recover the resulting project prolongation costs arising from the employer-caused critical delay.

Leaving to one side other potential costs such as disruption, the contractor should also be entitled to recover additional localised deferral or prolongation costs generated by such further varied work or deferred information flow where such costs do not form part of the valuation of the varied or other work.

[15] It may then be relevant to consider costs avoided as a result of the breach, such as

• savings through reduced learning curve effects in those local work activities that can now be spread over a longer period with fewer resources, or
• improved efficiencies working in less crowded than planned-for conditions.

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