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Estimating Concrete and

Rebar

Course objectives

Correctly setting up an estimate

Calculating the perimeter

Setting up the concrete foundation takeoff

Calculating concrete labor and materialcosts

Concrete takeoff for foundations

3 methods to use building line

center line

sectioning

Provide HO #1

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Building line estimates

Used for small projects (residential)

fast, easy

problem counts corners twice

Add perimeter (48 + 48 + 26 +26) = 148.0 ft. or 2(L + W)

148.0 ft x 8.0 ft x 0.83 ft = 982.72 cf.

Sectioning

Breaks construction down into smallerpieces

More accurate

More time consuming

Use where large volumes of concreterequired, but unusual angles, etc.

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Sectioning red 2) 24.33 ft x 8.0 ft x 0.83 ft = 323.10 cf.

blue 2) 48.0 ft x 8.0 ft x 0.83 ft = 637.44 cf. sum = 960.54 cf

Centerline length

Avoids adding corners twice

Most common method in commercial wk

Useful for conc., rebar, walls, etc.

Formula to know:

Outside Building line length or perimeter (4* thickness or width of any given strip)

Complete in-class activity #1calculate the amount of footingconcrete required

SOL = Po (4T)

distance from centerline of theconstruction line to the building line

= 10 inches (0.83 inches)

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Centerline length method

Building line length = (perimeter) = 148.0 ft

Distance from centerline to bldg. line =

148.0 ft (4*.83) = 144.67 (true perimeter)

144.67 ft * 8 ft * 0.83ft = 960.59 cf.

Centerline length caveat

Only works if all walls and offsets are 90

Quick estimating tip

Short cut for estimating concrete in anyfooting

Multiply the cross-section in square inchesby 0.000257. Gives CY/lineal ft

Multiply that result by number of lineal feetin the footing

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Quick estimating tip illustrated

Given: A footing 7-in deep and 22-in wideis 160-ft long.

Calculate the yards of concrete reqd.

(7" * 22")*160' * .000257 = 6.33 CY

DO NOT Convert inches to decimals except whenpart of next foot (e.g., 38-7)

Estimating footings (pads)

Estimating footings (pads)

List the description or title from scheduleProvide HO#2

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Calculating Rebar

Rebar weight perlinear foot

See text (pg. 133 forsplicing req.

Calculating formwork

2 Types Structural (concrete) formwork

Foundations

Walls

Columns

Beams

Flatwork (flat concrete work) Sidewalks

Driveways Slabs

Structural (concrete) formwork

Formwork measured in SFCA

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Measuring concrete walls

Use centerlinelength * height* 2

Refer to HO#1

Calculate the formworkand concrete required forthe wall

Labor placing concrete infoundations

50- 70 CY/8 hr day(direct from truck tofooting)

How is labor calculated?

Duration =Quantity of Work

Rate of Production

Using HO #1 calculate the duration of the footinginstallation

(0.35 labor hours/CY use a price of 35$/hour/man

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Course objectives

Correctly setting up an estimate

Calculating the perimeter

Setting up the concrete foundation takeoff Calculating concrete labor and material

costs