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Concrete / Sitework
Flat $199
This is the whole thing. Nothing held back.
Most estimating services show you a glossy summary page and keep the working
behind a signup form. Here is a complete concrete takeoff, every formula, every waste factor,
every assumption we had to make, and the eight questions we sent back to the contractor.
Check our arithmetic. That is the point.
Material Takeoff, Concrete
Light industrial slab on grade, single story
Project 60'-0" x 40'-0" shell
Footprint 2,400 SF
Documents S-1, S-2, A-1
Revision Bid set
01 Cast in place concrete
| Item | Calculation | CF | CY |
|---|
| Slab on grade5" thick, 4,000 psi |
60.0 x 40.0 x 0.4167 | 1,000 | 37.04 |
| Thickened edge12" x 12" below slab, continuous |
200 LF x 1.00 SF | 200 | 7.41 |
| Interior column pads(6) at 4'-0" x 4'-0" x 12" |
6 x 16.0 | 96 | 3.56 |
| Subtotal in place | 48.00 |
| Waste and spillage at 7% | 3.36 |
| Order quantity rounded up to the quarter yard |
51.50 CY |
Why 7 percent and not 10. The slab pours over compacted stone inside
steel edge forms, so loss is low. We carry 10 percent only on footings, uneven subgrade, or
formwork that can bulge. Ready mix sells in quarter yard increments and short loading a pour
costs far more than the extra concrete, so the round is always up.
02 Reinforcing steel
| Item | Calculation | LF | Weight |
|---|
| #4 slab mat, long way18" on center, 27 bars at 60'-0" |
floor(40 x 12 / 18) + 1 = 27 | 1,620 | n/a |
| #4 slab mat, short way18" on center, 41 bars at 40'-0" |
floor(60 x 12 / 18) + 1 = 41 | 1,640 | n/a |
| Subtotal, plus 10% for lap splices |
3,586 | 2,395 lb |
| #5 thickened edge(2) top and (2) bottom, continuous |
4 x 200 LF, plus 10% | 880 | 918 lb |
| Total reinforcing | 4,466 LF | 1.66 tons |
Order note. The #4 mat is 180 sticks at 20'-0". Weights use 0.668 lb/LF
for #4 and 1.043 lb/LF for #5. Chairs, tie wire and dowels are not included, see exclusions.
03 Under slab and finishing
| Item | Calculation | Quantity | Order |
|---|
| Base stone4" #57, compacted |
800 CF / 27 = 29.63 CY, +20% compaction, x 1.4 t/CY |
35.56 CY | 50 tons |
| Vapor barrier10 mil, seams lapped 6" |
2,400 SF + 10% lap |
2,640 SF | 2 rolls |
| Edge formworkperimeter, 2x lumber |
2 x (60 + 40) |
200 LF | 200 LF |
| Control jointssaw cut, 12.5' grid |
(4 x 40') + (3 x 60') |
340 LF | 340 LF |
Joint spacing. Rule of thumb is 2 to 3 times slab thickness in inches,
read as feet. A 5" slab gives 10 to 15 feet, and we used 12.5. If the structural engineer has
published a joint layout it governs over this assumption, see RFI 6.
04 Assumptions we had to make
| Where the documents were silent | What we carried |
|---|
| Slab thickness and strength not noted on S-1 | 5", 4,000 psi |
| Vapor barrier not specified | 10 mil per ACI 302 |
| Base course not specified | 4" compacted #57 stone |
| Control joint layout not provided | 12.5 foot grid |
| Finish not called out | Light broom |
| Column pad count read from plan, no schedule issued | 6 pads at 4' x 4' x 12" |
Every one of these is a number that moves if you tell us otherwise. That is
why they are listed instead of buried. An estimate without its assumptions written down is
not an estimate, it is a guess with a decimal point.
05 RFIs issued back to the contractor
- Rebar versus fiber reinforcement.Detail 3/S-2 calls for #4 at 18" on center each way. The general note on S-1 references synthetic fiber. These conflict. Which governs?
- Slab strength.No psi noted. Carried 4,000. Confirm, and advise if a mix design or admixture is specified.
- Thickened edge extent.Carried continuous around all 200 LF. Confirm whether it is required only at the loading side.
- Column pad schedule.Six pads scaled off S-1 with no schedule issued. Confirm count, dimensions and depth.
- Subgrade preparation.Assumed the pad is cut, filled and compacted by others to within tolerance. Confirm, and advise if over excavation or undercut is anticipated.
- Control joint layout.Assumed 12.5 foot grid. Provide the engineer's layout if one exists.
- Vapor barrier.Confirm mil thickness and whether taped seams and sealed penetrations are required.
- Embeds and anchor bolts.None shown on the concrete sheets. Confirm these are carried in the structural steel package.
Eight RFIs on a simple slab is normal. The RFIs are the part that protects
you at bid time. A takeoff that raises none has not read the drawings, it has measured them.
06 Excluded from this takeoff
- Excavation, cut and fill, spoil removal
- Formwork labor and shoring
- Placement, finishing and curing labor
- Testing, inspection and cylinders
- Chairs, bolsters and tie wire
- Anchor bolts and embed plates
- Sealer, hardener and coatings
- Dowels into existing construction
- Concrete pumping and access
- Winter or hot weather protection
- Sales tax, freight and short load fees
- Bonds, permits and general conditions
We publish exclusions in plain sight so nothing is assumed to be covered
that is not. The dangerous line item is always the one nobody wrote down.
What you noticedEvery formula is on the page
You can re-run all of it on a legal pad. If our arithmetic is wrong you will catch it in
ten minutes, which is exactly how it should work.
What you noticedThe assumptions are listed, not hidden
Six places the drawings were silent, six numbers we carried anyway, all disclosed. Change
any one and tell us, and the quantities move.
What you noticedWe sent questions back
Eight RFIs on a simple slab. Finding the fiber versus rebar conflict before bid day is
worth more than the takeoff cost.