How Concrete Subs Bid and Bill Commercial Work

By Wyatt Cooper · Published October 13, 2026 · 7 min read

Key takeaways

Price commercial concrete as a lump sum broken into pour-based lines, and add unit prices for the quantities nobody knows yet, such as extra footing depth.
Read the spec for who pays for testing and how often samples are taken; on a federal spec it is at least once a day and once per 150 cubic yards.
Build the schedule of values by element and pour (footings, slab on grade, decks, site concrete) so each month's billing matches what the GC can see in place.
Bill stored rebar and embeds only where the contract allows it, with the delivery tickets and the GC's agreement before the pay app goes in.

A concrete sub bids commercial work as a lump sum split by element and pour (footings, foundation walls, slab on grade, elevated decks, site concrete) plus unit prices for uncertain quantities. It reads the specification for testing, tolerances and finishes, schedules inspections before each pour, and bills monthly against a schedule of values built on those pours, with stored rebar billed only where the contract allows.

What a commercial concrete bid covers

Most commercial concrete is specified by reference to the American Concrete Institute's ACI 301, "Specifications for Concrete Construction", which covers materials and proportioning, reinforcement, "production, placing, finishing, and curing", formwork, joints, embedded items and repair of surface defects. Read the project's Division 03 sections for what it changes: mix strengths, finish tolerances, curing method and the testing regime.

Where scope usually splits on a commercial concrete package; your bid documents decide
Item	Often with concrete	Often with another trade	Write it down
Excavation for footings	Hand trimming and cleanup	Bulk and trench excavation (earthwork)	Who digs, who hauls the spoil
Reinforcing steel	Furnish and install, or install only	Furnished by a rebar supplier under the GC	Furnish, install, or both
Vapor retarder under slab	Supply and place	The waterproofing sub	Taped seams and penetrations
Anchor bolts and embeds	Set them	Furnished by steel or the GC	Who furnishes, who sets, who surveys
Testing	Contractor's quality control	The owner's testing agency	Who pays for retests after a failure
Winter protection	Blankets and curing	Heat and enclosure (the GC)	As a unit price per day or excluded

Add unit prices for what can't be measured on bid day: footing concrete per cubic yard below the design depth, rock excavation, and extra slab thickness. If the GC's bid form has no line for them, list them in your qualifications. In Conflo, those go in the bid's qualifications or an attached schedule, since a trade bid's fields are the base bid, scope items, alternates, exclusions and qualifications.

Inspections and tests around each pour

Before a pour, plan for the inspections the job requires (rebar placement, embeds, forms) and the testing agency on site. The federal unified guide specification for cast-in-place concrete (UFGS 03 30 00) has strength samples taken for each mixture placed each day "not less than once a day, nor less than once for each" 150 cubic yards, "nor less than once for each" 5,000 square feet of slab or wall surface. Your project spec may differ; read its testing article.

After the pour, forms come off only when the concrete can carry its own weight and the loads on it. OSHA (29 CFR 1926.703) allows removal once that is shown by the conditions in the plans and specifications or by tests to an appropriate ASTM method, and requires the formwork drawings to be available at the jobsite.

Slab pour 2 — 310 cubic yards over 18,000 square feet in one day

Once a day: 1 sample set
Once per 150 cubic yards: 310 ÷ 150 = 2.07, so 3 sets
Once per 5,000 square feet of slab: 18,000 ÷ 5,000 = 3.6, so 4 sets
Required: The largest: 4 sample sets for the day

How many strength-test samples one fictional slab pour needs under the federal frequencies.

A worked example: the schedule of values and a pay app

A made-up sub, Granite Line Concrete, holds a $612,000 lump-sum subcontract on a two-story office. It splits the value by element so each line can be seen and measured.

Granite Line Concrete's schedule of values and its second pay app (fictional, 10% retainage).
Line	Scheduled value	Complete to date	Billed to date
Footings and foundation walls	$186,000	100%	$186,000
Slab on grade	$214,000	40%	$85,600
Elevated deck	$148,000	0% (rebar stored on site: $22,000)	$22,000
Site concrete (curbs, walks)	$64,000	0%	$0
Total	$612,000		$293,600

Pay app 2 — Granite Line Concrete

Completed and stored to date: $186,000 + $85,600 + $22,000 = $293,600
Less retainage at 10%: $29,360
Earned less retainage: $264,240
Less previous payments: Pay app 1: footings 60% = $111,600, less 10% = $100,440
Current payment due: $264,240 − $100,440 = $163,800
Check: This period: $74,400 (footings 40%) + $85,600 + $22,000 = $182,000, less 10% = $163,800

The second pay app's math on the fictional job. The first pay app billed footings at 60%.

The $22,000 of stored rebar is billable only if your subcontract allows it. The AIA's general conditions (A201–2017 §9.3.2) allow payment for materials "delivered and suitably stored at the site", and off site only if the owner approves in advance; subcontracts usually pass the same terms down. Send the delivery tickets with the pay app. More on the arithmetic in how retainage is calculated and how a sub fills out a pay app.

Change orders on concrete work

Concrete changes are often quantity changes: a footing deepened after the soils engineer looks at the bearing, or an added equipment pad. That's where your bid's unit prices pay off. If the subcontract carries a unit price of $285 per cubic yard for added footing concrete and the engineer adds 12 cubic yards, the change is 12 × $285 = $3,420, with no argument over the rate. Without a unit price, price it the way how to price a change order shows, and give notice within your subcontract's deadline.

How it works in Conflo

When a GC invites you to a trade bid in Conflo, you see your own invitation, ask questions (the answers go to every bidder without your name), acknowledge addenda, and submit a base bid, each scope item marked included or excluded with an optional breakout, alternates, exclusions and qualifications. There is no unit-price field on a bid today: list unit prices in your qualifications or attach your schedule.

Once you are under contract, you bill monthly in pay apps against your schedule of values: percent complete this period and materials stored for each line, with previous billing carried forward, retainage calculated, and no line billed past 100%. The GC approves it or sends back the lines that are wrong with a note. Billing is by percent, not by quantity times unit price, so enter the percent your measured quantities represent.

The same pay app as the electrical subcontractor sees it in Conflo: waiting on the GC, the payment steps, what is holding payment, the application summary and the schedule of values with this period, stored and to-date amounts. — A subcontractor's pay app in Conflo: who it is waiting on, the payment steps, what is holding payment, and the schedule of values with this period, stored and to-date amounts.

The bottom line

Bid concrete as a lump sum split by element and pour, with unit prices for the quantities nobody knows yet and a clear line on rebar, embeds, testing and winter work. Bill against those same lines each month, stored materials only where the contract allows.

Subcontractors invited by a GC use Conflo free. Join the waitlist to bid and bill your next job in it.

Join the waitlist

Sources

ACI SPEC-301-20, Specifications for Concrete Construction (product description) — American Concrete Institute. Read October 16, 2026.
UFGS 03 30 00, Cast-in-Place Concrete (February 2019, change 10) — Whole Building Design Guide (USACE, NAVFAC, AFCEC). Read October 16, 2026.
29 CFR 1926.703, Requirements for cast-in-place concrete — Occupational Safety and Health Administration. Read October 16, 2026.
Summary: A201–2017, General Conditions of the Contract for Construction — AIA Contract Documents. Read October 17, 2026.

Questions

Should a concrete sub bid lump sum or unit price?

Commercial building work is usually lump sum, because the drawings define the quantities. Add unit prices for what can't be measured on bid day, such as footing concrete below design depth or rock excavation, so changes are priced by an agreed rate.

Who pays for concrete testing?

It depends on the specification. Often the owner hires the testing agency, and the contractor pays for retests after a failure. Some specs put quality-control testing on the contractor. Read the testing article and say in your bid which tests you carry.

Can a concrete sub bill for rebar delivered to the site?

Usually, if the contract allows payment for stored materials. AIA A201–2017 allows materials suitably stored on site and, with the owner's advance approval, off site. Check your subcontract and send delivery tickets with the pay app.

How should a concrete schedule of values be split?

By element and pour: footings and foundation walls, slab on grade (by pour if it is large), elevated decks, and site concrete. Lines the GC can see in place are easier to approve than one line for all concrete.