Question

1-A building requires a 100-foot long by 83-foot wide by 5-inch thick concrete slab. Using a waste factor of 10 %, Include calculations. a)determine the number of cubic yards of concrete needed to pour the slab. (2 points)

2-Determine the number of rolls of wire mesh needed if there are 750 SF of wire per roll and 12% of waste. Include calculations. (2 points) 9 BCT 2770 Estimating Fundamentals

3-Determine the amount of rebar needed for the slab if it is reinforced with #4 rebar at 12 inches on center both ways. Assume 2 inches of cover and add 10% for lap and waste. Include calculations.(11 points) Tip=Use the density method

4-Determine the cost to finish the slab using a productivity of 0.011 labor hours per SF and an average labor rate of $29.92 per labor hour. Include calculations.(2 points)

5-A vapor barrier is to be placed below the slab. Determine the number of 10-foot by 100-foot rolls of vapor barrier needed. The vapor barrier needs to be lapped one foot. Hint: Subtract the lap from the width of the roll. Include calculations. (2 points)

Answer 1

Ans 1) Required volume (V) = L x B x H

=> V = 100 ft x 83 ft x (5 in/12 in/ft)

=> V = 3458.33

Since, 10% contribute to waste , actual volume required = (1 + 0.1) x 3458.33 = 3804.16

1 cubic yard = 27

=> Required volume = 3804.16 / 27 /cy = 140.90 cy

Hence, required volume of concrete is 140.9 cy

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Ans 2) Total area = 2 (LB + BH + HL)

=> Total area = 2 [(100 x 83) + (83 x 0.416) + (0.416 x 100)]

=> Total area = 16752.3 sq.ft

1 roll covers 750 sq.ft area, so number of rolls required = 16752.3/ 750 = 22.34 rolls

Include 12% waste, actual number of roll required = 22.34 x 1.12 = 25 roll

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Ans 3) Number of rebar (N) required can be calculated as :

N = (Total length - clear cover) / Spacing

=> N = [(83 ft x 12 in/ft) - 2 in - 2 in] / 12

=> N = 82.67 83

Area of #4 rebar = 0.20 sq.in

=> Volume of 1 bar = 0.20 sq in x 100 ft x 12 in/ft = 240

=> Volume of 83 bar = 83 x 240 = 19920 or 11.53

=> Density of rebar = 475 lb/

Hence, rebar requied = 475 lb/ x 11.53 = 5476.75 lb

.

Ans 4) From part 2, area of slab = 16752.3 sq.ft  

Labor productivity = 0.011 labour hr /sq ft x 16752.3 sq.ft = 184.28 hr

=> Labour cost = 184.28 hr x 29.92$/hr = 5513.65 $