Contractual Procedures And Estimating Engineering Essay

In construction area, the accurate and complete of the cost estimation is the key to success profitability of the construction project. Cost estimation is utilized as one of the main implements of successful cost management for the project. A good estimator should understand in the construction materials, the method and system of the construction. This is very important for them to do the estimating as well as the labour and equipment required to complete the entire mission in their correct categorisation on time and on budget. In this task, we will try to discuss and estimated according to the task given which is excavation, formwork, reinforcement bar, BRC, concrete and brick wall. We should do the estimation for each task according to the calculation. But each task represented different calculation method. Therefore, we have to calculate according to the correct step to show the correct estimation for each task.

SOLVING QUESTION

2.1 EXCAVATION 1

Find the rate per m3 for excavating a foundation trench starting at ground level in no exceeding depth 1.5, average 1.2m and for removing all surplus excavated materials from site using hand labour loading into 5m3 dumpers. Excavation is done 60% by hand and 40% by 1/4m3 excavator. Cost per hour is RM 85.00 including operator. A banksman is needed at RM40.00 per day. The spoil heap is deposited on ground before loading into lorry.

A labourer will excavate 1m3 in 4 hours. This excludes throwing spoil into lorry for disposal. Loading of 5m3 of soul will take 6 men’s in 1.75 hours at RM4.00 per hour. For one trip including loading and uploading will take 2 hour. Cost of lorry including driver and fuel is RM 65.00 per hour. Bulking is 25%. Output of excavation for excavator and hand excavation are given for normal ground as 9m3/hour. Overhead and profit are charged on 15%. Cost for labour is RM 60/day

Approximate the rate (per m3) for specified works/activities

Topic

Calculation

Cost (RM/1m3)

Excavation by hand (60%)

Cost of labour:

RM60/8hour x 4hour = RM30/m3

RM30 x 0.6= RM18 /m3

18.00

Excavation by excavator (40%)

Banksman:

RM 40/8hour/9m3= RM 0.56 m3

Excavator:

RM85/9m3= RM9.44/m3

Excavation:

RM 0.56 + RM9.44 = RM10/m3

RM10/m3 x 0.4= RM4/m3

4.00

Removing:

Cost of Lorry:

RM65 x 2 hour= RM130

Loading :

6x 1.75hour x RM4=RM42

REMOVING:

RM130+RM 42=5m +25%

RM172=6.25 m3

1 m3=RM27.52

27.52

TOTAL:

49.52

PROFIT (15%)

49.52 X 15%= 7.43

7.43

Cost of excavation work

45.52+6.83=52.35

56.95 The rate per m3 for excavating a foundation trench starting at ground level in no exceeding depth 1.5, average 1.2m is RM 56.95

2.2 EXCAVATION 2

Find unit rate per m3 for excavating a pit for pad, starting at ground level inclusive removing all surplus excavated materials from site using hand labour loading 6m3 into lorry. Excavation is done 2/5 by hand and 3/5 by excavator. The excavator cost is RM80.00 per hour including the operator. A banksman is needed at RM5.00 per hour.

a labourer will excavate 1m3 in 3.5 hour. This excludes throwing spoil into the lorry for disposal. Loading of 6m3 of soil will take 6 men’s in 1.75 hour at RM5.00 per hour. One trip including loading and unloading output of excavation for excavator and hand excavation is given for RM65/hour for normal soil . Assume output of excavator is 8.5m3/hour. Assume cost for labour is RM60/day. Overhead and profit are allowed at 10 %

Estimate the rate (per m3) for the specified work.

Topic

Calculation

Cost (RM/1m3)

Excavation by hand (2/5)

Cost of labour:

RM60/8hour x 3.5hour = RM26.25/m3

RM26.25/m3 x 2/5= RM10.50 /m3

10.50

Excavation by excavator (3/5)

Banksman:

RM 5/8.5m3= RM 0.59 m3

Excavator:

RM80/8.5m3= RM9.41/m3

RM 0.59 + RM9.41 = RM10/m3

Excavation:

RM10/m3 x 3/5= RM6/m3

6.00

Removing:

Cost of Lorry:

RM65 x 1 hour= RM65

Loading :

6x 1.75hour x RM5=RM52.50

REMOVING:

RM65+RM 52.50=6 m3

6 m3= RM 117.50

1 m3=RM19.58

19.58

TOTAL:

36.08

PROFIT (10%)

39.08 X 10%= 3.61

3.61

Cost of excavation work

39.08 + 3.61=52.35

39.69 The unit rate per m3 for excavating a pit for pad is RM39.69

2.3 REINFORCEMENT BAR

Calculate the cost per kilogram of 25mm diameter high yield steel reinforcement bars based on the following information. Given:

Material cost: 25mm diameter bars delivered to site = RM 1,250.00 per tonne

Using a labourer for Stacking and off-loading = RM5.00 per hour per 100kg

Tie wire is o.66kg/100kg of reinforcement bar at RM 3.20/kg

Allow spacers = RM4.00 per tonne of reinforcement bar

Allow for rolling margin RM 25.00 per tonne of reinforcement bar

Allow 5% wastage

Labour cost

One skilled labourer and one unskilled labourer at RM6.00 per hour and RM4.00 per hour respectively

Allow 10% idling time

Time analysis for 100kg of reinforcement bar:

.select = 20 minutes

Cut = 27minute

Bend = 35 minutes

Fix = 23 minutes

Hoist twice = 9 minutes

Overhead and profit = 15%

Topic

Calculation

Cost (RM/kg)

Cost of Materials

Reinforcement bar:

RM1250/1000kg=RM1.25/kg

Tie wire:

RM3.20 x 0.66 kg=RM1.25/kg

Allow spacer:

RM4/1000kg=RM0.003/kg

Rolling Margin:

RM25/1000kg=RM0.03/kg

Total material cost:

RM1.25/kg+ RM1.25/kg+ RM0.003/kg+ RM0.03/kg=RM3.39/kg

Wastage (5%)

RM 3.39 X 5%=RM0.17/kg

Total :

RM3.39/kg+ RM0.17/kg= RM3.56/kg

3.56

Cost of Labour

Total of time:

20+27+35+23+9=114 minute

Idling time:

114x 10%=11.40minute

Total time:

114+11.4 =125.4 minute

125.4minute/60minute=2.09 hour

Cost for Skill labourer:

RM6 x 2.09= RM17.40/100kg

17.40/100kg =RM0.13/kg

Cost for Unskill labourer:

RM4 x 2.09= RM8.36/100kg

RM8.36/100kg =RM0.08/kg

Cost for Stacking and off-loading:

RM5/100kg = RM0.05/kg

Total cost of labour:

RM0.13/kg+ RM0.08/kg+ RM0.05/kg

= RM0.26

0.26

TOTAL:

3.82

PROFIT (15%)

3.82 X 15%= 0.57

0.57

Cost of reinforcement bar

3.82+0.57=4.39

4.39 The cost per kilogram of 25mm diameter high yield steel reinforcement bars is RM4.39

2.4 FORMWORK

Estimate the total cost of formwork to construct the suspended transfer beams (non-perimeter) size 750mm wide x 1200mm deep x 3000 mm long in 15 numbers without crossing each other. Thickness of suspended slab is 125 mm

Given:

12mm plywood at RM36.00 per m2

Cutting waste is 15%

0.06 m3 of props and struts per m2 above beam at RM560.00 per m3

Allow 3 uses for timber

Wastage on each use is 10%

Nails and bolts at RM2.00 per m2

2 joiners and 4 labourers take 12 hour to erect and fix this formwork (for all the 15 number of beam)

Labour cost for joiner at RM8.00 per hour

Labour cost for labourer at RM 5.50 per hour

Overhead and profit: 10%

Topic

Calculation

Cost (RM/m2)

Cost of materials

Plywood per m2

RM 36.00/m2

Strut per m2

RM 560 0.06m3= RM 33.60/m2

Total of materials

RM 36.00/m2+ RM 33.60/m2=RM 69.60/m2

Cutting waste 15%

RM 69.60/m2+15%= RM 80.04/m2

1 uses for timber

Allow 3 uses for timber

RM 80.04/m2 3= RM 26.68/m2

Nails and bolts per m2

RM 2.00/m2

Total of cost materials use

RM 26.68/m2+ RM2.00/m2=RM28.68/m2

Add 10% wastage of each use

RM28.68/m2+10%=RM 31.55/m2

31.55

Cost of labour

Joiner

RM8/hr x 2 joiners x 12hr/15x [(1.2mx 3m) + (1.2m x 0.75m)]x 2

=RM 1.42/m2

Labourer

RM 5.5/hr 4 labors 12hr / 15 [(1.2m 3m) + (1.2m 0.75m)] 2

=RM1.96/m2

Total

RM 1.42/m2+ RM1.96/m2

= RM 3.38/m2

3.38

31.55+3.38

34.93

Profits 10%

34.93 x 10%=3.49

3.49

Total

34.93+3.49

38.42 Cost of formwork = RM 38.42/m2 1.2m 3m 2 = RM 276.62/m2

= RM 38.42/m2 0.75m 1.2m 2 = RM 69.16/m2

RM 345.78/m2

The total cost of formwork to construct the suspended transfer beams (non-perimeter) size 750mm wide x 1200mm deep x 3000 mm long in 15 numbers without crossing each other is RM5186.70 (RM345.78 x 15)

2.5 CONCRETE

Calculate the cost (per m3) of concreting a beam 400mm x 450 mm x 4000mm

Cost of concrete (ration= 1 :3 : 6)

Ordinary Portland cement = 1420 kg/m3 @ RM 10.00/50kg

Sand = 1600kg/m3 @ RM30.00 per tonne

Coarse aggregate = 1400kg/[email protected] RM 40.00 per tonne

Shrinkage, consolidation and wastage @ 5%

Cost of labour and machine (5/31/2 mixer)

Labour gang : 5 nos. At RM3.50 per hour m3

Mixer output @ 1.2 m3 per hour

Cost per of mixer including fuel is RM5.00

Additional labour for hosting and placing of concrete into beams = 0.6 hour per m3 @ RM3.50 per hour

Additional labour working around reinforcement is 0.55 hour @ RM3.50 per hour per m3

Cost of vibrator is RM 6.50 per hour, per m3

Overhead and profit is 10%

Topic

Calculation

Cost (RM/m3)

Cost of Materials

Cement:

1429kg/50kg x RM10 x 1=RM284

Sand :

1600kg/1000kg x RM 30 x 3=RM144

Coarse:

1400kg/1000kg x RM 40 x 6=RM336

Total cost materials(10m3):

RM284+RM144+RM336=RM764

Wastage (5%)

RM764 x 5%=RM38.2

Total:RM764+38.20=RM802.20

Total cost materials (1m3)

RM802.20/10m3=RM80.22

80.22

Cost of Labour & Machine

Labour of mixer

5 x RM3.50 / 1.2m3= RM 14.58

Cost for mixer

5 x RM5.00 / 1.2m3= RM 20.83

Additional labour for hosting and placing

0.6hour x RM3.50= RM2.10

Additional labour working around reinforcement

0.55hour x RM3.50 =RM 1.93

Cost of vibrator

RM6.50 x 1 = RM 6.50

Total Cost Labour & Machine

RM 14.58 + RM 20.83+ RM2.10+ RM 1.93+ RM 6.50= RM45.94

45.94

TOTAL:

126.16

PROFIT (10%)

126.16 X 10%= 12.61

12.61

Cost of concrete

126.16 + 12.61= 138.78

138.78 The cost (per m3) of concreting a beam is RM138.78, Cost for concreting a beam 400mm x 450 mm x 4000mm is RM99.92 (RM138.78 x 0.4 x 0.45 x 4)

2.6 BRC

Estimate the total cost of 1 bottom layer of BRC A7 in car porch slab measuring 2500mm x 4000mm x 150mm thick ( concrete cover = 25mm)

Given:

List price of BRC A7 is RM72.60 per sheet of 6.00m x 2.20m. A discount of 25% from price is offered by the supplier.

Laps and wastages for the BRC is 12%

Allow tying-wire and spacer block at RM1.00 per m2 of mesh reinforcement

2 labourers unload and fix 10m2of BRC A7 in car porch slab in one hour

Cost of labourer is RM45.00 per day

Overhead and profit is 10%

Topic

Calculation

Cost (RM/m2)

Cost of Materials

BRC

RM 72.60 75 %( 100-25%)=RM54.45/m2

1m2 of BRC

RM 54.45/m2/(6 x 2.2)= RM 4.13/m2

Addition allow tying wire and spacer

RM 4.13/m2+RM 1.00/m2= RM 5.13/m2

Add 12% wastage

RM 5.13/m2+12%= RM 5.75/m2

5.75

Cost of Labour

Labor

RM45/day 8hr 2 labors 1hr/10m2 = RM 1.13/m2

1.13

TOTAL:

RM 5.75/m2 + RM 1.13/m2=6.88m2

6.88

PROFIT (10%)

6.88 x 10%=0.69

0.69

Cost of BRC work

6.88+0.69

7.57 Cost of BRC A7 (per m2) = RM 7.57 2.5m 4m

= RM 75.70

The total cost of 1 bottom layer of BRC A7 in car porch slab measuring 2500mm x 4000mm x 150mm thick ( concrete cover = 25mm) is RM 75.70

2.7 BRICK WALL

Calculate the total cost of a brick wall measuring 8 m long and 3m high with damp proof course (DPC) and “EXMET” brick reinforcement. The thickness of the brick wall is a one and half brick (1 ½ brick thick)

Given:

Material cost = RM103.50 pcs per pallet

59 pieces of brick are needed for every one square meter of half brick wall.

Wastage on brick 5%

Output is 120 bricks per hour bricklayer

Labour gang for walling is 3 bricklayer s and 2 labourers

Cement and san mortar (1:3) needed is 0.08 m3 / m2 of 1 ½ brick thick wall.

Wastage for “Exmet” is 5 %

1 bricklayer and 1 labourer can lay 82m of “exmet” brick reinforcement for 2 hour

500 bricks (1 pallet)

Mortar = RM80.00/m3

Bricklayer = RM 70.00/hour

Labourer = RM55.00/hour

Exmet (82 m long) = 250.00/m

Fibre based bituminous felt damp-proof course laid horizontally and bedded in cement and sand (1:3) mortar. Bedding mortar is disregarded since it has been included in the brickwork

1m2 of brick wall above requires 0.4m2 of DPC

Wastage 5%

Laps 5%

2 bricklayers and 1 labourer, can lay 1m2 of DPC in 0.25hour

Overhead and profit 15%

DPC = RM5.00/m2

Topic

Calculation

Cost (RM/m3)

Cost of brick

Brick per pieces

RM103.50/500= RM0.21

Quantity of brick(1m3)

59 x 3 = 177pieces

Wastage of brick (5%)

177 x 105=186 pieces

Cost of brick

186 x RM0.21= RM 39.06

39.06

Cost of Labour (walling)

Cost for 3 bricklayer s and 2 labourers

3 x 70 x =RM309.75

2 x 55 x = RM162.25

Total: 309.75+162.25= RM 472

472.00

Cost of Mortar

0.08 x 80 = RM6.40

6.40

Cost of Exmet

Quantity of exmet:

=3.33;

Wastage 5%

3.33 x 105%=3.50

Cost per m for exmet:

RM250/82m=RM3.05

Cost of exmet

3.05 x 3.50= RM10.68

10.68

Cost of Labour (Exmet)

1 bricklayer and 1 labourer can lay 82m

x 2 x 3.33=RM4.47

x 2 x 3.33=RM5.69

Total labour cost

RM4.47+ RM5.69=RM10.16

10.16

DPC

1m2=0.4m2

Wastage 5%+Laps 5%

5%+5%=10%

Quantity

0.4×110%=0.44

Cost of DPC

0.44 x RM5= RM2.20

2.20

Cost of Labour (DPC)

2 bricklayers and 1 labourer

2 x RM70 x 0.25 x 0.4=RM14.00

1 x RM55 x 0.25 x 0.4=RM5.50

Total of labour cost

RM14.00+ RM5.50=RM19.50

19.50

Total cost of brick wall (Cost of brick, Cost of Labour (walling), Cost of Mortar, Cost of Exmet & Cost of Labour (Exmet).

39.06+472.00+6.40+10.68+10.16=538.3

538.3 x 8 x 3= 12919.20/m2

12919.20

Total cost of DPC

(2.20+19.50)x8 =173.60

173.60

TOTAL of brick wall:

13092.80

PROFIT (15%)

13092.80 x 15%

1963.92

COST OF BRICK WALL

13092.80+1963.92=15056.72

15056.72

The total cost of a brick wall measuring 8 m long and 3m high is RM15056.72

3.0 CONCLUSION

In conclusion, cost estimation is very important in construction area. This is because when the wrong estimation of the cost per m2 will lead the loss of profits for the contractor. Therefore, the estimator must have the professional ability and cautious to do the estimation. From the solution above, we can conclude as below

2.1 answers is the rate per m3 for excavating a foundation trench starting at ground level in no exceeding depth 1.5, average 1.2m is RM 56.95.

2.2 answers is the unit rate per m3 for excavating a pit for pad is RM39.69

2.3 answers is the cost per kilogram of 25mm diameter high yield steel reinforcement bars is RM4.39

2.4 answers is the total cost of formwork to construct the suspended transfer beams (non-perimeter) size 750mm wide x 1200mm deep x 3000 mm long in 15 numbers without crossing each other is RM5186.70

2.5 answers is the cost (per m3) of concreting a beam is RM138.78, Cost for concreting a beam 400mm x 450 mm x 4000mm is RM99.92

2.6 answers is the total cost of 1 bottom layer of BRC A7 in car porch slab measuring 2500mm x 4000mm x 150mm thick ( concrete cover = 25mm) is RM 75.70

2.7 answers is the total cost of a brick wall measuring 8 m long and 3m high is RM15056.72

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