12.3 Job Cost Control and Change Order Management
Key Takeaways
- Cost control is a weekly loop — record actual cost by cost code, compare it to the estimate at the same percentage of completion, identify the variance, act on it, and re-forecast the job at completion.
- Labor is the controllable variance on a roofing job, because material quantities are largely fixed by the takeoff while labor hours move with slope, access, weather, and crew composition.
- Under B&P § 7159.6 extra work or a change in scope on a residential home improvement contract requires a written change order signed by both parties before the extra work begins, describing the scope, the cost, and any effect on the completion date.
- A change order should be priced the same way the original bid was priced — direct cost plus overhead and profit as a margin — rather than at bare cost, because extra work consumes the same overhead as base work.
- The most common reason a roofing contractor is not paid for extra work is that the work was performed before it was authorized in writing, which converts a collectible change order into a disputed claim.
Job Cost Control and Change Order Management
Quick Answer: Cost control is a weekly loop: capture actual cost by cost code, compare it to the estimate at the same percentage of completion, name the variance, act on it, and re-forecast the cost at completion. Labor is where roofing jobs are won or lost, because the material quantity is fixed by the takeoff while labor hours move with slope, access, weather, and crew. And when the scope changes, the rule on residential work is absolute: B&P § 7159.6 requires a written change order signed by both parties before the extra work begins. Work performed before it is authorized is not a change order — it is a claim, and claims lose.
1. The Weekly Cost Control Loop
- Capture. Field time by employee, cost code, and job; material invoices coded to the job; subcontract billings; equipment hours; other direct costs.
- Compare. Cost to date against the estimate at the same percent complete. Comparing dollars spent to the total budget on a half-finished roof tells you nothing.
- Diagnose. Is the variance quantity, productivity, price, or scope? Each has a different fix.
- Act. Change the crew mix, change the sequence, correct a rework cause, or issue a change order if the variance is scope.
- Re-forecast. Update the projected cost at completion so the company knows what this job will actually earn while there is still time to respond.
The Four Variance Types
| Variance | Cause | Response |
|---|---|---|
| Quantity | The takeoff was wrong, or the field is consuming more than ordered | Re-measure; fix the estimating assumption for the next bid |
| Productivity | Hours per square exceed the estimate | Look at slope, access, crew composition, staging, weather, and rework |
| Price | Material or labor unit cost exceeds the estimate | Renegotiate, substitute an approved equal, or escalate the future bid |
| Scope | The work is outside the contracted scope | Stop. Issue a change order. This is not a cost problem — it is a contract problem |
The Metric That Warns First
If the estimate assumed 5.0 hours per square on a 6:12 architectural shingle roof and the first four squares consumed 26 hours, the job is running at 6.5 hours per square — 30 percent over — on day one. That is actionable. The same information arriving in a month-end financial statement is not.
Track rework hours separately. Rework is pure loss, and its causes — a misread layout, a skipped detail, a wrong fastener — recur until someone names them.
2. Recognizing a Change-Order Condition
On a roofing job the triggers are predictable:
- Deck condition worse than the allowance carried in the bid — rot, delamination, inadequate thickness, spaced sheathing under a tile conversion
- Additional layers discovered at tear-off beyond what was disclosed
- Hazardous or unknown materials requiring testing and possibly abatement
- Structural conditions — sagging rafters, undersized framing for a heavier covering
- Owner-requested upgrades — a different product line, added skylights, gutter replacement
- Code or inspector requirements not in the contract documents — added ventilation, a required cricket, a fire-zone vent upgrade
- Differing site conditions — buried utilities in the staging area, restricted access, an HVAC unit that must be lifted
The discipline: the moment a crew finds one, stop that portion of the work, photograph it, measure it, and get the change order signed before anyone touches it.
3. The Statutory Rule on Residential Change Orders
B&P § 7159.6 governs extra work and change orders on a residential home improvement contract:
- The change order must be in writing
- It must be signed by both the contractor and the owner
- It must be executed before the extra work begins
- It must describe the scope of the added or deleted work, the cost adjustment, and any change to the estimated completion date
There is no oral change order, no "we'll paper it Friday," and no implied authorization from a homeowner nodding at a photograph. A contractor who replaces 14 sheets of rotten plywood on a handshake and bills for it has created a disputed charge, a likely CSLB complaint, and a weak collection position — regardless of how obviously necessary the work was.
The practical fix is the unit price in the original bid (Section 12.2). When the contract already says plywood replacement is $X per sheet, the change order is a one-line document signed in five minutes on the driveway, not a negotiation.
New for 2026 on private commercial work: SB 61 also added change-order dispute requirements to private-works payment law. Confirm the current text before relying on a contract form written earlier.
4. Pricing a Change Order
Price extra work the way you priced the base work. Extra work consumes the same overhead — the same supervision, the same truck, the same office — so pricing it at bare cost silently funds the customer's upgrade out of your profit.
Worked example. Fourteen sheets of 15/32-inch CDX plus labor:
| Item | Amount |
|---|---|
| Material: 14 sheets at $62.00 | $868.00 |
| Labor: 6 crew-hours at a $45.12 burdened rate | $270.72 |
| Added disposal | $95.00 |
| Direct cost | $1,233.72 |
| Price at a 25 percent margin: $1,233.72 ÷ 0.75 | $1,644.96 |
Write it on the change order as a single price with the scope described — "Remove and replace 14 sheets of deteriorated 15/32-inch CDX roof sheathing at the north slope; includes disposal; adds one working day" — not as a cost-plus invitation to audit your labor rate.
Time and materials is appropriate only where the scope genuinely cannot be defined in advance. When you use it, agree the labor rate, the material markup, and a not-to-exceed ceiling in writing first, and submit daily tickets signed by the owner or their representative.
5. Documenting the Job So the Money Is Collectible
Every roofing project should generate: a daily log (crew, hours, weather, work performed, deliveries, inspections, visitors, delays); photographs at tear-off, deck, dry-in, and completion; signed change orders; inspection records; delivery tickets matched to invoices; written correspondence confirming every verbal instruction; and a weekly cost report with the projected cost at completion.
This file is worth money in three different ways: it supports the change order, it defends the callback, and it is the evidence base if the account has to be collected through the lien remedies in Section 11.3.
During a residential reroof, the crew tears off and finds 14 sheets of rotted plywood. The homeowner is standing in the driveway and says "just fix it." What must the contractor do before replacing the sheathing?
A roofing job estimated at 5.0 crew-hours per square has consumed 26 hours to install the first 4 squares. What does this indicate and when should the contractor act?
How should a change order for extra deck replacement be priced?