Question

Estimate the total cost for furnishing and installing floor joist and plywood sub-flooring given the following information:

a. Size of the building: 32 feet long and 18 feet wide

b. Spacing of floor joists: 2 feet on center

c. Double joist on ends plus joist header and footer

d. Size of floor joists: 18 feet long of 2x8 lumber

e. Productivity Rate: Lumber - 20 crew-hrs/MBFM and Plywood - 12 crew-hrs/MSF

f. Crew’s Wage Rate: $27.50/wk-hr

g. Material Costs: Lumber - $550/MBFM and Plywood - $1,100/MSF

TOTAL BOARD REQUIRED BFM -?

TOTAL PLYWOOD REQUIRED SF - ?

LUMBER MATERIAL COST $ LS -?

PLYWOOD MATERIAL COST $ LS -?

TOTAL MATERIAL COST $ LS -?

TOTAL LABOR COST $ LS - ?

TOTAL COST $ LS - ?

Answer 1

Step 1: Calculation of length of joists along the short edge:

Given Data:

· Size of the building: 32’ x 18’

· Spacing of floor joists: 2’ O.C.

· Double joist on ends plus joist header and footer

· Size of floor joists: 18’ x 2” x 8”

Total number of joists including end joists = 15 + 2 x 2 = 19 numbers

Length of each joist = 18’

Total Length = 19 x 18 = 342 ft

Step 2: Calculation of length of joist header and footer:

Given Data:

· Size of the building: 32’ x 18’

· Spacing of floor joists: 2’ O.C.

· Double joist on ends plus joist header and footer

· Size of floor joists: 18’ x 2” x 8”

Length of each header and footer = Length of building = 32’

Header and footer will be provided one at each end.

Hence total length of joist header and footer = 2 x 2 x 32 = 128 ft

Step 3: Total Board Feet measure (BFM) and MBFM (Thousand Board feet measure) of lumber:

Given Data:

· Length of floor joists along short edge= 342’

· Length of joists for header and footer = 128’

1 Board feet = 1 ft x 1 ft x 1 in

Hence,

Total MBFM = BFM/1000 = 626.67/1000 = 0.6267 MBFM

Step 4: Calculation of Square feet (SF) and MSF (Thousand Square feet) of plywood:

Given Data:

· Size of the building: 32’ x 18’

SF of plywood = Plan area of building = 32 x 18 = 576 SF

Total MSF = SF/1000 = 576/1000 = 0.5760 MSF

Step 5: Calculation of required crew hours:

Given Data,

· Total quantity Lumber = 0.6267 MBFM

· Total quantity plywood = 0.5760 MSF

· Productivity Rate Lumber - 20 crew-hrs/MBFM

· Productivity Rate Plywood - 12 crew-hrs/MSF

Required crew hours for lumber fixing = 20 x 0.6267 = 12.53 hours

Required crew hours for plywood fixing = 12 x 0.576 = 6.91 hours

Total crew hours = 12.53 + 6.91 = 19.44 hours

Step 3: Cost Estimate:

Given Data:

· Crew’s Wage Rate: $27.50/wk-hr

· Material Costs Lumber - $550/MBFM

· Material Costs Plywood - $1,100/MSF

Cost estimate prepared in below table:

Sl. No.	Particulars	Unit Cost	Quantity	Unit	Amount
1	Material Lumber	$550.00	0.6267	MBFM	$344.69
2	Material Plywood	$1,100.00	0.5760	MSF	$633.60
3	Labor for fixing lumber and plywood	$27.50	19.44	hr	$534.60
	Total cost for the job				$1,512.89

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