Quantum: extended site overhead

Extended site overhead is usually the largest single head of a delay claim. When the project runs longer, the contractor keeps paying for site staff, trailers, temporary services and equipment. The principle is simple: the contractor recovers the time-related costs of the compensable delay. The detail is where claims are won and lost: which costs truly run with time, at what rate, and for how many days.

Learning outcomes

• Distinguish time-related site costs from quantity-related and one-time costs.
• Build a daily site overhead rate from cost records.
• Audit a claimed daily rate line by line.
• Apply the rate only to compensable days.

The lesson

What counts

Time-related costs vary with how long the contractor is on site: site management and supervision, site offices and facilities, temporary utilities, small tools and equipment kept on site, and insurance or bond extensions where premiums actually increase. Quantity-related costs vary with the amount of work, such as materials and trade labour, and are not extended by delay. One-time costs, such as mobilization, do not repeat.

Building the rate

The best rate comes from actual costs during the delay period, not from the bid. Take the cost ledger for the period, keep only time-related costs, and divide by the days. CCDC 2-2020 GC 6.5 allows reasonable costs for owner-caused delay, and GC 6.6 requires records sufficient to substantiate the claim [1].

Auditing a claimed rate

• Is each cost truly time-related, or would it have been incurred anyway?
• Is the cost from the delay period, or an average across the job?
• Are staff actually on this project during the delay, at actual cost?
• Are insurance and bond extensions supported by premium invoices?
• Are bonuses, profit or head office costs hiding in the rate?

Which days

Apply the rate only to compensable days, and to the period when the delay actually happened. Site overhead at the end of a project, during commissioning, is often lower than at its peak; using a peak rate for an end-of-job delay overstates the claim.

Northgate worked example

Northgate Distribution Centre (fictional) is a 12,000 m² tilt-up warehouse in Vaughan, Ontario, built by Halvorsen Builders Ltd. (fictional) under CCDC 2-2020, with Ridgeline Architects Inc. (fictional) as Consultant. See the Northgate fact sheet. This course follows one delay claim from first notice to settlement. Ready-for-Takeover (M9) was due Friday, January 14, 2028 and was reached on Tuesday, March 14, 2028: 60 calendar days late. All events, dates and amounts are illustrative.

Halvorsen claimed 60 days at $8,700 per day: $522,000. The owner's representative audited the daily rate from Halvorsen's cost ledger for December 2027 to March 2028, the period of the owner's dock leveller delay (Figure 1).

Two lines changed. Equipment fell from $1,400 to $700 a day, because a telehandler and lift claimed as delay-related were on site for base-scope commissioning anyway. Insurance and bond fell from $400 to $200, matching the premium extension invoices. A $600 superintendent bonus was removed: it was a completion incentive, not a time-related cost. The audited rate is $7,200 per day.

View the data

Item	Value
Claimed: 60 days × $8,700	$522,000
Entitled: 18 days × $7,200	$129,600

Applied to the 18 compensable days, the result is $129,600. The other 42 days claimed were neutral, concurrent or Halvorsen's own, which earn no site overhead under the contract and the concurrency clause.

Your move

If you are the owner

• Audit the rate from the ledger for the delay period. Not from the bid.
• Remove costs that would have been incurred anyway. Ask what changed because of the delay.
• Ask for premium invoices. Insurance and bond extensions must be real.
• Apply the rate to compensable days only.

If you are the contractor

• Code time-related costs separately from day one. It makes the rate easy to prove.
• Use actual costs from the delay period. A rate built from the period is hard to attack.
• Leave out incentives and profit. They are not site overhead.
• Show who was on site. Timesheets for each person in the rate.

Common mistakes

1. Using the bid rate. Actual period costs are the evidence.
2. Applying the rate to all delay days. Only compensable days count.
3. Peak rate for an end-of-job delay. Use the period when the delay happened.
4. Including equipment on site anyway. No change, no claim.
5. Bonuses and profit in the rate. They are not time-related costs.

Quick quiz

1. Which cost is time-related?

   1. Concrete
   2. Site superintendent
   3. Mobilization
   4. Rebar

2. What is the best source for a daily rate?

   1. The bid
   2. Actual time-related costs during the delay period
   3. An industry average
   4. The owner's budget

3. Why was the equipment line reduced at Northgate?

   1. It was too old
   2. The equipment was on site for base scope anyway
   3. It was rented
   4. It was not invoiced

4. What is 18 days × $7,200?

   1. $108,000
   2. $129,600
   3. $156,600
   4. $522,000

5. To which days does the site overhead rate apply?

   1. All 60 days
   2. Compensable days only
   3. Concurrent days only
   4. Weekends

Show answers and explanations

1. B. Site management runs with time.
2. B. Period costs from the ledger.
3. B. No change caused by the delay means no claim.
4. B. 18 × 7,200 = 129,600.
5. B. Neutral, concurrent and contractor days earn no site overhead here.

Key terms

Extended site overhead

Time-related site costs incurred because the project ran longer.

Time-related cost

A cost that varies with time on site rather than with quantity of work.

Daily rate

Time-related cost per day during the delay period.

Compensable day

A day of delay for which the contractor is entitled to costs.

Cost ledger

The contractor's record of costs by cost code and period.

References

1. Canadian Construction Documents Committee, CCDC 2-2020 Stipulated Price Contract, GC 6.4 to 6.6 and Part 8. Clause content checked against a publicly posted tender copy; buy the form from CCDC.
2. Fenwick Elliott, The SCL Delay and Disruption Protocol: a second edition (November 2017), summarizing the Society of Construction Law Protocol, 2nd edition (February 2017).
3. Miller Thomson LLP, Ontario Court underlines the evidence and analysis required to establish critical path delays (July 2021).
4. BRC, Northgate fact sheet (fictional case study, v1, November 4, 2026).

Verified on November 9, 2026.

Next lesson in this trackHead office overhead formulas