How Do Concrete Contractors Send Estimates? Access First

Short answer: Concrete contractors send estimates a day or two after the site visit, and the visit decides more than the arithmetic does, because how the mix reaches the forms sets the price before anything is measured. The document names the mix strength in psi, the thickness, the base depth, the reinforcement, the finish, and the joint plan, and it carries the yardage — ft² × thickness in feet ÷ 27, which is ft² ÷ 81 for a 4 in slab. Hold the price against a dated plant quote.

Concrete is bid on two units at once: the plant sells you volume, the customer buys surface, and the money is made or lost in everything sitting between them. An estimate that only shows a square-foot price has hidden the parts that actually vary. Below is the order the number gets built in, what the document has to say, and how it goes out while the homeowner is still collecting bids.

What decides the price before anything gets measured?

How the concrete gets from the drum to the forms. Walk the access before you pull out a tape, because two identical patios on two lots are not the same job.

Site condition	How the mix arrives	What it does to the number
Truck backs right up to the forms	Straight off the chute, which reaches roughly 14 to 18 ft past the rear of the truck with the extensions on	Cheapest case, smallest crew
Just past chute reach	All the extensions plus a hand moving them	Small labor adder, and a slower discharge
Backyard through a gate	Wheelbarrows or a power buggy, a fraction of a yard at a time	Placement labor doubles or worse, and you need more bodies on a fixed finishing clock
No line of sight, over a house, tight urban lot	Line pump or boom pump	Day rate plus a yardage minimum, and a second vendor to schedule
Long straight shot, no truck room	Conveyor truck	Rental plus operator
Soft ground, new sod, or a finished driveway in the path	Plates, mats, or placing from the street	Restoration risk, and a repair allowance that belongs on paper

The finishing clock is why this matters more than in other trades. Once the load starts moving, the crew is racing set time. A buggy job needs more hands than a chute job for the same yardage, and staffing that decision wrong is how a profitable patio becomes a scramble.

How does the yardage get calculated?

Area in square feet, times thickness in feet, divided by 27. In practice that collapses into one divisor per thickness.

Slab thickness	Divide ft² by	480 ft² patio	960 ft² driveway
4 in	81	5.9 yd³	11.9 yd³
5 in	64.8	7.4 yd³	14.8 yd³
6 in	54	8.9 yd³	17.8 yd³
8 in, footings and thickened edges	40.5	11.9 yd³	23.7 yd³

Then add 5 to 10 percent for the things the geometry does not show: subgrade that is never perfectly flat, thickened edges, overdig at the perimeter, and the wash-out at the end. Thickened edges and footings get calculated on their own and added, not averaged into the field thickness.

One ordering fact drives real money on small work. A standard mixer carries about 10 yd³, and anything meaningfully under a full truck picks up a short-load surcharge from the plant. A 5.9 yd³ patio pays it. Two 5 yd³ pours on the same street, ordered on different days, pay it twice. Sequencing pours so they share a truck is an estimating decision, not a scheduling one, and it belongs in the number before the number goes out.

What has to be named on the estimate before the price appears?

Concrete disputes are almost always specification disputes wearing a price costume. Every row below is something a customer will otherwise assume in the most expensive direction.

Block	What the line has to say
Mix strength	psi at 28 days, plus air entrainment where freeze-thaw applies
Thickness	Slab thickness in inches; thickened edges and footings stated separately
Base	Compacted aggregate depth in inches, material named, and how it gets compacted
Reinforcement	Welded wire, or bar size and spacing, and how it is held at height — chairs, not pulled up mid-pour
Fiber	Named if it is included, and never described as a substitute for bar
Finish	Broom direction, hard trowel, exposed aggregate, or stamp pattern and release color
Joint plan	Spacing, depth, method, and timing, written out
Cure	Curing compound, wet cure, or blankets
Sealer	Product type, number of coats, and when the second coat happens
Weather protection	Cold- and hot-weather placement priced as a named conditional adder
Access	Chute, buggy, pump, or conveyor — and who protects the lawn and drive
Washout	Where the chute and the drum get rinsed, and who supplies containment
Exclusions	Drainage design, landscape restoration, sprinkler and private utility lines, final grading

The washout row looks like a housekeeping detail and is not. Rinse water off a chute is highly alkaline, and under the federal construction stormwater program EPA requires washout wastes to be contained rather than discharged to the ground or a storm drain. The federal permit itself attaches at one acre of disturbance, so most residential flatwork sits outside it — but states and municipalities apply their own rules well below that threshold, and a homeowner whose lawn dies in a gray circle is a homeowner with a restoration claim either way. Name the washout location on the estimate, or bring a washout bag and price it.

Write the joint plan in plain numbers, because it is the single line that prevents the most common post-job argument. Control joint spacing at roughly 24 to 36 times the slab thickness in inches, read as feet, puts joints every 8 to 12 ft on a 4 in slab. Depth at a quarter of the thickness or more. Cut within about 6 to 18 hours of finishing, and sooner in hot, dry, windy conditions. Alongside it, one sentence: hairline shrinkage cracking occurs in all concrete and is not a defect, and joints determine where it goes rather than whether it happens. Customers who read that before signing rarely bring it up afterward.

How do I price the subgrade I cannot see?

As conditional unit lines, dormant on the signed estimate until they are triggered, photographed, and confirmed by text. Concrete’s unknowns are all under the grass.

• Undercut and import structural fill, by the ton or the yard, when the excavation finds fat clay, organics, or a soft pocket that will not compact.
• Existing slab demolition, priced by square foot at a stated thickness with reinforcement noted, because a 6 in wire-reinforced driveway is a different demo from a 3 in patio.
• Root removal, by the tree, plus the note that a slab poured over a cut root system moves.
• Buried debris or an old footing, hourly with equipment.
• Water, when the hole holds it — dewatering and a stone blanket are labor and material, not a courtesy.
• Utility conflicts, after the locates come back, with the reminder in writing that public locates do not mark private irrigation, invisible fence, or landscape lighting.

The rule that keeps these from becoming disputes: the price exists before the shovel does. A number produced after the surprise reads as opportunism, and the same number sitting on a page the customer signed reads as a plan.

How do I build the price instead of borrowing a per-foot number?

From your own costs, in this sequence.

Step	The concrete version
1. Carry two units	Cubic yards buy the mix, square feet sell the slab, and forms and joints are linear feet
2. Material from the unit	Mix at the specified psi plus your overage, short-load surcharge under a full truck, base stone by the ton, wire or bar with chairs and ties, form lumber and stakes spread across the pours they survive, curing compound, sealer, admixtures
3. Equipment	Pump or conveyor day rate plus yardage minimum, saw and blades, plate compactor, skid steer or mini excavator, dump trailer
4. Labor from the unit	Excavation and haul-off hours, forming hours per linear foot, steel setting, the placement and finish window itself, the return trip to cut joints, the return trip to strip forms and clean up
5. Overhead	Truck, fuel, insurance, workers’ comp, license, tool replacement, the hours spent estimating jobs you did not win
6. Profit	Applied as margin, not as markup

Those two return trips in step 4 are the ones most often left out. Joint cutting happens hours after the crew went home, and stripping forms happens a day or more later — both are windshield time and both are billable cost that never shows up in a per-foot figure copied off a forum.

Step 6 quietly costs more than any other line. Markup and margin are different arithmetic. A driveway that costs you $6,400 all in, marked up 25 percent, prices at $8,000 and yields $1,600 of profit — a 20 percent margin, not 25. To actually hold 25 percent, divide the cost by 0.75 and price at $8,533. On one job that is $533. Across a season it is the mini excavator.

Published per-square-foot and per-yard ranges are a sanity check only. They move with region, plant pricing, fuel surcharges, decorative finish, access, and season. Use them to notice that you are off by a factor of two, never to set the number.

How fast does the estimate go out, and in what form?

Job	Site visit to estimate	How it goes
Sidewalk section, small pad, steps	Same visit	Written and left, or texted as a PDF before you drive off
Patio or a single-car driveway	24 to 48 hours	PDF by email or text
Garage slab, footings, multi-pour work	3 to 5 days	PDF with a scope page and the pour sequence
Builder or general contractor	On the bid date	PDF on their form, with unit prices
Commercial flatwork	On the bid date	PDF with a separate inclusions and exclusions page

Homeowners collect three concrete bids in a week, and concrete bids are unusually hard to compare because thickness, psi, base depth, and reinforcement all move independently. That is an advantage for whoever spells them out. A cheaper bid with no spec on it invites the question you want asked: how thick, what strength, how much stone, what steel.

How long does the price stay good, and what does the weather do to it?

Put a calendar date on the page rather than a duration, and tie it to your plant quote, which has its own expiration and its own fuel and environmental surcharges.

Then handle the season explicitly, because concrete has two temperature regimes that cost real money. ACI 306 treats cold weather as air temperature that has fallen, or is expected to fall, to 40°F or below during the protection period — which means heated mix, accelerating admixtures, insulating blankets, and monitoring until the slab has strength. ACI 305 sets no single hot-weather temperature; it defines hot weather as the combination of heat, wind, and low humidity that accelerates moisture loss and hydration, which drives evaporation retarders, cooled mixes, dawn starts, and fogging. Name both as conditional adders rather than absorbing them, and state that the pour date is a target subject to weather. Concrete crews get bumped by rain, and a customer who was told that in writing does not treat a delay as a broken promise.

How does acceptance get recorded, and what happens after?

Written acceptance every time: a signature on the page, a typed approval by email, or a photo of the signed sheet. Tie the deposit to the physical order — base stone, form lumber, and steel — rather than to a round percentage, and check your own state first, since several cap what a home improvement contractor may collect before work starts. Add one sentence to the acceptance block and then honor it: changes to thickness, strength, finish, or scope are priced in writing before the work happens.

From there the estimate stops being the live document and becomes a deposit receipt, plant delivery tickets, stone scale tickets, a rental invoice, and finally the bill built against the same lines. What separates the deposit receipt from the invoice is sorted out in invoice vs receipt, and the fields the final bill needs are in what to include on an invoice.

Keel is an iOS app that handles the after-the-signature half on the phone, entirely on the device — no account, no bank connection, no cloud, no login, and an App Store privacy label reading Data Not Collected. It does not write estimates; what it does is turn a signed job into paper in about a minute. The deposit invoice and the final invoice carry your own numbering, logo, and brand color, with the payment link rendered as a QR code the customer scans off your screen while standing on the finished slab. Batch tickets, stone scale tickets, pump rental invoices, and sealer receipts get photographed and read on-device by Apple Intelligence, so the yardage and the cost stay attached to the job instead of curling in a door pocket. Trips to the plant, the quarry, and back to the site get logged as mileage — the record that has to exist is described in IRS mileage log requirements. Freeboard shows cash minus tax reserve, minus committed invoices, minus a buffer, which matters when a deposit lands weeks before the plant invoice does. Year end exports as a single file, or as the Accountant Pack: a CSV plus a one-page summary PDF, over an append-only hash-chained ledger. Free is $0 with unlimited invoices, receipts, and mileage; Keel Pro is a one-time $249.99 lifetime purchase, not a subscription. You can get it on the App Store. When the balance stalls anyway, the sequence is in concrete customer won’t pay.

Frequently asked questions

How long does it take a concrete contractor to send an estimate?

Same visit for a sidewalk section or a small pad, 24 to 48 hours for a patio or a driveway, and three to five days for footings or a multi-pour job. Builder and commercial bids go out on the due date rather than early. The delay that loses work is not the takeoff, it is the estimate sitting unwritten in the truck while two other bids reach the kitchen counter.

How many yards of concrete do I put on the estimate?

Square feet times thickness in feet divided by 27, which simplifies to ft² ÷ 81 for a 4 in slab, ÷ 64.8 at 5 in, ÷ 54 at 6 in, and ÷ 40.5 at 8 in. Add 5 to 10 percent for subgrade irregularity and overdig, calculate thickened edges and footings separately, and remember that anything well under a full truck of about 10 yd³ picks up a short-load surcharge.

Should the estimate say what psi the concrete is?

Yes, on its own line with the 28-day strength and any air entrainment. Strength is the cheapest thing on the page to specify and one of the easiest for a competitor to quietly leave out. A customer comparing three bids has no way to see that one of them is a weaker mix over less stone unless the numbers are printed where they can be compared.

How should I handle bad soil I only find during excavation?

With a conditional line already sitting on the signed estimate: undercut and imported structural fill priced by the ton or yard, triggered only when the excavation exposes it, documented with a photo, and confirmed by text before the crew continues. Pricing it before the shovel goes in makes it a plan. Pricing it after looks like a surprise charge, no matter how honest the number is.

How long should a concrete estimate stay valid?

Write a calendar date rather than a duration, and tie it to your plant’s quote, which carries its own expiration and its own fuel and environmental surcharges. Add the seasonal note too: cold-weather protection under ACI 306 kicks in when temperatures fall to or below 40°F during the protection period, and hot, dry, windy placement brings its own measures. Both are adders, not absorbed costs.

Does the estimate need a joint plan on it?

It should. Write the spacing, the depth, and the timing — roughly 24 to 36 times the slab thickness in inches read as feet, cut at least a quarter of the thickness deep, within about 6 to 18 hours of finishing. Pair it with one sentence explaining that hairline shrinkage cracking happens in all concrete and that joints control where it appears. That sentence prevents more withheld payments than any other line on the page.

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This article is general information, not professional or tax advice.