Lecture 1 INTRODUCTION

Transcription

1 COURSE NAME: DETAILS OF CONSTRUCTION ESTIMATING COURSE NO: CE-200 Lecture 1 INTRODUCTION Definition: An estimate for any construction work may be defined as the process of calculating the quantities and costs of the various items required in connection with the work. It is prepared by calculating the quantities from the dimensions of the drawings, the various items required to complete the project and multiplied with the unit cost of item concerned. Purpose of Estimating: To ascertain the necessary amount received by the owner to complete the proposed work and arranging fund for the same. For public work construction estimates are required to obtain administrative approval, allotment of fund and technical sanction. To ascertain the quantity of materials required for programming timely procurement. To know the number of different categories of works that is to be employed to complete the work within the schedule time of completion. Helps to assess the requirements of Tools, Plants and equipments required to complete the work according to the programme. To fix up the completion period from the volume of work involved in the estimate. To justify the investment from benefit cost ratio. Estimate is required to invite tender and preparation of bills for payment. Estimate for existing property is required for valuation Different types of estimates: There are different types of estimates and they are as follows: 1. A detailed Estimate 2. A preliminary or rough Estimate 3. A quantity Estimate 4. Revised Estimate 5. Supplementary Estimate 6. A complete Estimate A detailed Estimate: This includes the detailed particulars for the quantities, rates and costs of all the items involved for satisfactory completion of a project. A preliminary Estimate: This is an approximate estimate made to find out an approximate cost in a short time thus enable the responsible authority concerned to consider the financial aspect of the scheme for according sanction to the same. A quantity Estimate: This is a complete estimate or list of quantities for all items of work required to complete the concerned project.

2 Revised Estimate: Revised Estimate is a detailed estimate for the revised quantities and rates for items of works originally provided in the estimate without material deviations of a structural nature from the design originally approved for a project. Supplementary Estimate: While a work is in progress, some changes or additional works due to material deviation of a structural nature from the design originally approved may be thought necessary for development of a project, an estimate is then prepared to include all such works. This is known as supplementary estimate. A complete Estimate: This is an estimated cost of all items which are related to the work in addition to the detailed estimate. How to prepare a detailed Estimate: The procedure of preparation of a detailed estimate is divided into two parts, a) Details of measurement and calculation of quantities b) Abstract of Estimated cost Details of measurement and calculation of quantities: Include respective measurements for dimensions for all individual items involved in the whole work are taken off from the drawing of the work and entered in the respective columns of a standard measurement form as shown below. Multiplying item wise respective dimensions quantities of all items are worked out in the measurement form.

3 Measurement form: Item No. Description No Length Breadth Height or Depth Quantity Abstract of Estimated cost: is the second part in the preparation of a detailed estimate. The cost of each and every individual item of work is calculated by multiplying the quantity computed in the measurement form with the specified rate in a tabular form known as Abstract form and are added all together to get the actual estimated cost of work. This estimated cost of work is increased by 3-5% for any unforeseen expenditure and is called Contingencies. To maintain additional supervising staff at work site called Work charged establishment, a further amount of 2.5% is directly charged to the estimate prepared from item of work. Thus by summation of cost obtained by adding all items, contingencies and work charged establishment a detailed estimate is prepared. Item No Description Quantity Unit Rate Amount Factors to be considered during preparation of a detailed Estimate: Quantity of materials Availability of materials Transportation of materials Location of sites Local Labour charges Lump-sum item: Sometimes a lump-sum rate is provided for certain small items for which detailed quantities cannot be taken out easily or it takes sufficient time to find the detail, as front architectural or decoration work of building, site cleaning etc. Main items of work for Building estimates: Earthwork in excavation for foundation trenches: Earth is excavated for for foundation trenches to the exact width and depth of foundation with vertical sides and the bottom leveled both longitudinally and transversely. The quantity of earthwork is calculated by taking the dimensions of each trench length x breadth x depth. Earthwork in filling: This consists of two parts: (a) foundation trenches and (b) plinth filling. Normally excavated earth from foundation trenches is used for filling. (a) : For foundation filling: Quantity of earthwork = Volume of work in excavation Volume of work in foundation. (b) Plinth filling: Earthwork in plinth filling is calculated by taking the internal dimensions in between plinth wall and height is taken after deducting the thickness of concrete in floor.

4 Concrete in foundation: The concrete in foundation is taken out in cu-ft by length x breadth x thickness. The length and breadth of concrete are usually same as for excavation, only the thickness differs. Soling: When the soil is soft or bad, one layer of dry brick or stone soling is applied below the foundation concrete. The soling layer is computed in sq-ft (length x breadth) specifying the thickness. Damp Proof Course: This is usually a layer of cement concrete mixture in the proportion of 1:2:4 mixed with water proofing compound laid in between the plinth and superstructure walls to prevent the rise of water by capillary action from the ground. The quantity is estimated in sq-ft multiplying the length and breadth. The thickness is described in the description column. Masonry: Masonry is computed in cu-ft(length x breadth x height). Foundation and plinth masonry is taken under one item and masonry in superstructure is taken in another item. In storied building the masonry in each story is computed separately. In taking out quantities the walls are measured as solid and then deductions are made for openings as doors, windows etc. R.C.C work: Reinforced concrete may be for columns, beams, lintels, roof slabs etc. The quantity is worked out in cu-ft including reinforcement. The volume occupied by reinforcement is not deducted from the volume of concrete. The quantity of reinforcement is found separately. Centering and shuttering (Form work): The cost of formwork is about 30% of cement concrete. Unless otherwise specified formwork is measured separately. Flooring: Ground floor means floor on plinth. The floor consists of two parts, (1) bottom floor with cement concrete (1:3:6) over a flat soling (Soling is done to prevent the contamination of concrete with earth below it), (2) the top part which may be different types. The quantity is measured in sq-ft. Plastering: Plastering usually ½ thick is calculated in sq-ft.for walls the measurements are taken for the whole face of the wall for both sides as solid and then deduction for openings are made. ANALYSIS OF RATES Definition: The determination of rate per unit of a particular item of work, from the cost of quantities of materials, the cost of laborers and other miscellaneous petty expenses require for its completion is known as the analysis of rate. A reasonable profit, usually 10% for the contractor is also included in the analysis of rate. Purposes of rate analysis: To determine the current rate per unit of an item at the locality.

5 To examine the viability of rates offered by contractors To calculate the quantity of materials and labour strength required for project planning To fix up labor contract rates. How to fix up rate per unit of an item: The following sub heads are estimated and a summation of these is the rate per unit of an item. a) Quantity of materials and cost b) Labor costs c) Costs of equipments or tools and plant. d) Overhead e) Profit Quantity of Course aggregate, sand and cement for different proportions: In the analysis of rate per cu-m or cft, at first a volume of 1 cu-m has been considered in calculation. But it is difficult to assess exactly the amount of each material required to produce 1 cu-m of wet concrete when deposited in place. To find out the volume of cement, sand and course aggregate assume 1 cu-m of wet concrete needs cu-m of dry mix. In case of brick chips the value is taken as Analysis of Rate: Example-1: Cement concrete 1:2:4 with graded stone chips for R.C.C works. Solution: Consider volume of course aggregate = 1 cu-m Total proportion = = 7 Cement = 1.54* 1/7 = 0.22 cu-m Sand = 1.54* 2/7 = 0.44 cu-m or 0.22*2 = 0.44 cu-m Stone chips = 0.22*4 = 0.88 Particulars Quantity (cu-m) Rate Amount Cement /- Materials Sand /- Stone chips /- Labour Labour - -./- Contingencies 5%./- Water charges 1%./- Profit./- Rate Per cu-m =./- SPECIFICATIONS Specification: A specification is a specific description of a particular subject. Specification specifies or describes the nature and the class of the work, materials to be used in the work, workmanship etc and is very important for the execution of the work. The cost of a work depends much on the specifications.

6 Necessity of specifications: The cost of an unit quantity of work is govern by its specifications. Required to describe the quality and quantity of different materials required for a construction work and is one of the essential contract document. A work is carried out according to its specification and the contractor is paid for the same. Specification includes: a) Description of materials b) Workmanship c) Tools and plants d) Protection of new work General specifications of a first class building: 1. Foundation and plinth: Brickwork in foundation and plinth shall be of the first class brick in cement mortar over cement concrete. 2. Filling: Foundation trenches and plinth shall be filled up with course sand. 3. D.P.C: D.P.C shall be 2.5 cm thick cement concrete.mix ratio is 1 : 1.5: 3 4. Superstructure: Superstructure shall be of the first class brickwork in cement mortar. 5. Flooring: Mosaic flooring shall be provided in to all floors including staircase. 6. Roofing: The roof shall be 10 cm R.C.C Slab with 10 cm average lime terracing over it. 7. Finishing: Inside and outside shall be 12mm cement plastered. The inside of drawing, dining and bed rooms shall be distempered and rest portions white washed three coats. The outside shall be color washed over three coats of white wash. 8. Doors and windows: Doors and windows frames shall be of seasoned teak wood and shutters of 3cm thick wood paneling, Brass fitting shall be provided. Doors and windows shall be varnished with French polish. 9. Miscellaneous: Rain water pipes shall be of Asbestos cement or cast iron, finished with paint. All sanitary, water supply and electrical fittings shall be of first class materials.

7 COURSE NAME: DETAILS OF CONSTRUCTION ESTIMATING COURSE NO: CE-200 Lecture 2 DIFFERENT METHODS FOR ESTIMATING BUILDING WORKS: The quantities of various items such as earthwork in excavation, foundation concrete, brickwork in foundation and plinth, brickwork in superstructure etc can be estimated by any of the following three methods: 1) Long and short wall method 2) Centre line method 3) Crossing method 4) Long and short wall method: In this method the longer walls in a building are considered as long walls and measured from out -to-out and the shorter walls, in a perpendicular direction of the long walls are considered as short walls and measured from in-to-in for a particular layer of work. To calculate the length of long and short walls determine first there centre to centre lengths individually from the plan. Then the length of long wall, out-to-out may be calculated after adding half breadth of wall at each end with its centre to centre length. Thus the length of short wall measured into-in may be found out after subtraction half breadth at each end from its centre to centre length. Centre line method: In this method calculate the total centre line length of walls in a building and multiply the same by the breadth and depth of the respective item to get the total quantity at a time. For different sections of walls in a building, the centre line length for each type shall be worked out separately. In case of Partition wall or verandah walls joining with main wall the centre line length shall be reduced by half of the breadth of the layer of main wall that joins with the partition or verandah wall at the same level. Number of such joints are studied first to calculate the centre line length. By this method estimates may be prepared more quickly and this methods as accurate as the other methods. Crossing method: In this method calculate the overall perimeter of the building and subtract from this four times thickness of wall to obtain the centre line length. Internal walls are grouped separately to their sections and measured in between the internal faces of the main wall at that level. Principally this method is same as the centre line method but differs the process of calculations to find the centre line lengths.

8 DETAILED ESTIMATE OF A TWO STORIED RESIDENTIAL BUILDING: General Specification: 1. Foundation and plinth: Brickwork in foundation and plinth shall be of first class brick in cement mortar (1:4) over cement concrete (1:3:6) 2. Filling: Foundation trenches shall be filled up with excavated earth and the plinth shall be filled up with local sand. 3. Damp-Proof-Course: DPC shall be of cement concrete (1:2:4) with water proofing compound. 4. Superstructure: Shall be of first class brickwork in cement mortar (1:6).Wall thickness are 10inch. 5. Roofing: The roof shall be of 5inch R.C.C slab with 3.5in lime terracing over it. Concrete mix ration is 1:3:6 6. Flooring: The under bed of ground floor shall be of 3inch thick CC laid over a layer of brick flat soling. 7. Plastering: Inside and outside walls shall 1/2inch thick cement mortar(1:6). Ceiling and sunshade shall be of 1/4inch cement plastered (1:4). 8. Doors and windows: 9. Painting: Given: #. Plan of a two storied building with detailed dimension #. Detailed section of the building #. Floor to floor height = 10ft #. Door, D1 = 3.5 x 7, D2 = 3 x 7, D3 = 2.5 x 7 #.Window, W1 = 4 x 4, W2 = 3 x 4, W3 = 2 x 4 Calculation of Long and short wall: Outer long wall (2 No) = 45 ft Outer short wall (2 No) = 26ft 10in * 2 Wall 1 = 26ft 10in *2 Wall 2 = 14ft Wall 3 (2 No) = 10ft + 6in + 1ft Wall 4 (1 No) = 16ft + 10in + 7ft 2in + 6in + 4ft Wall 5 (1 No) = 8 ft

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13 Details of Measurment and Quantities No Description of item No L (ft) B (ft) H (ft) Quantity Unit SUB HEAD I : EARTHWORK Earthwork in excavation Outer long wall cft Outer short wall cft 1 Wall cft Wall cft Wall cft Wall cft Wall cft Total Earthwork = cft Sand filling for plinth Bed room cft Bed room cft Drawing room cft Dining room cft 2 Kitchen with passage cft Toilet with passage cft Stair case cft Store room cft Toilet cft Total sand filling for plinth = cft Earthwork in filling Total Earthwork in excavation cft 3 Deduct : Concrete foundation cft Brickwork in foundation (up to G.L) cft Brick soling cft Total Earthworkin filling = cft Notes Breadth 5' = 4' + 1' (space) Height 5' means from foundation level to Ground level (G.L) In case of L, B..Inner dimension are taken 2.5' = 3'(bet n G.L & P.L) 3"(for CC) 3"(Brick soling) 17.83' = 11'+10"+6' 2.67' = ((22+42)/2)/ ' = 10"+10"+10"+1 0" 4 5 SUB HEAD 2 : CONCRETE WORK Concrete in foundation Outer long wall cft Outer short wall cft Wall cft Wall cft Wall cft Wall cft Wall cft Total concrete in foundation = cft 1" thick D.P.C Outer long wall sft Outer short wall sft Wall sft Wall sft Wall sft Wall sft Wall sft P.W sft P.W sft Total = sft Deduction : DPC is usually a layer of cement concrete mixture in the proportion 1:2:4 mixed with water proofing compound laid in between the plinth and

14 Door, D cft D cft D cft Collapsible gate cft Net total = cft 6 Concrete in slab cft Concrete in lintel Outer long wall cft Outer shor wall cft 7 Wall cft Wall cft Wall cft P.W cft Total concrete in lintel = cft Concrete in stair Base on toe wall cft 8 Waist slab of flight cft Landing (lower& at 1st floor) cft Steps cft Total concrete in stair = cft Concrete in Sunshade Window,W cft 9 Window,W cft Window, W cft Total concrete for sunshade = cft Concrete in flooring Bed room cft Bed room cft Drawing room cft Dining room cft 10 Kitchen cft Store room cft Toilet cft Toilet cft Passage between toilet and din cft Total concrete in floor = cft superstructure walls to prevent the rise of water by capillary action from the ground. Lintel X section : 10" x 6" 0.5' = 6" 9.43 = sqrt ( ) where, 5' = 1/2 of height of one floor 0.25' = 3" (CC) Inner dimension are taken SUB HEAD 3 : BRICKWORK Brick flat soling Main wall sft Toe wall sft Total brick flat soling = sft Brick flat soling in floor Bed room sft Bed room sft Drawing room sft Dining room sft Kitchen sft Store room sft Toilet sft Toilet sft Passage between toilet and din sft Total brick flat soling = sft

15 13 14 Brick work in foundation Up to G.L 1st footing cft 2nd footing cft 3rd footing cft 4th footing cft From G.L to P.L cft Total brickwork in foundation = cft Brickwork in superstructure Outer long wall cft Outer short wall cft Wall cft Wall cft Wall cft Wall cft Wall cft P.W cft P.W cft Total = cft Deduction: For Door, D cft D cft D cft For Windwo, W cft W cft W cft For lintel = cft Total deduction = cft Net total B.W in superstructure = cft 3.5' = 42" 2.83' = 34" 2.33' = 28" 1.83' = 22" PW = 8' (Toilet wall 6" wall) PW 22' = 11'(Drawing)+ 6'(kitchen)+ 5'(toilet)...(all are 6" wall) SUB HEAD 4 : PLASTERING 15 1/2" thick Cement plaster to wall Inside plastering : Bed room sft Bed room sft Drawing room sft Kitchen sft Store room sft Toilet sft Toilet sft Stair case sft 15(a) Total = sft Deduction : For Door, D sft D sft D sft For Windwo, W sft W sft W sft Total deduction = sft Net total inside plastering = sft Outside plastering sft Deduction = 15(b) sft 50' = 2*(14+11) 53' = 2*( ) 50' include all inside wall of the bed room

16 15(b) Net total outside plastering = sft Total amout of plastering = sft 1/4" plastering in ceiling Bed room sft Bed room sft Drawing room sft Dining room sft Kitchen sft Store room sft Toilet sft Toilet sft Passage between toilet and din sft Stair case : Under waist slab sft 1st landing sft Underside of 1st floor landing sft Total plastering = sft 1/4" plastering in Sunshade For Windwo, W sft W sft W sft Total plastering = sft 142 = 2*(45+26) 13.33' = 11' + 10" + 6' 5' (for toilet)

17 Abstract of Estimated Cost No Description of item Qty Unit Rate(/=) Unit Amount(/=) SUB HEAD 1: EARTHWORK 1 Earthwork in excavation 5913 cft cft.. 2 Earthwork in filling cft cft 3 Sand filling for plinth cft cft SUB HEAD 2 : CONCRETE WORK 4 Concrete in foundation (1:3: cft cft 5 Concrete in slab (1:3:6) cft cft 6 Concrete in lintel (1:3:6) cft cft 7 Concrete in stair (1:3:6) 80.1 cft cft 8 Concrete in sunshade (1:3:6) cft cft 9 Concrete in flooring (1:3:6) cft cft 10 1" thik DPC (CC 1:2:4) sft sft SUB HEAD 3: BRICKWORK Brick flat soling in foundation sft Brick soling in floor sft Brick work in foundation cft Brickwork in superstructure cft Total Brickwork cft Total Brickwork sft Brick (9.5"x4.5"x2.75") no Brick (9.5"x4.5"x2.75") no 11 Total No of brick No per 1000 SUB HEAD 4 : PLASTERING 12 1/2" Plaster (1:6) 3840 sft sft 13 1/4" Plaster (1:4) 1012 sft sft 14 SUBHEAD 5 : WOOD WORK 15 SUBHEAD 6 : STEEL & IRON WORK 16 SUBHEAD 7 : FLOORING 17 SUBHEAD 8 : PAINTING 18 SUBHEAD 9 : W.SUPPLY & SANITATIO Total cost = Add 5% contingency = (5% of total cost) Add 2.5% workcharge establishment = (2.5% of total cost) GRAND TOTAL = (Total cost + contingency + workcharge ) Plinth Area = 45' x 26' Rate per sq ft = Grand total / plinth area

18 COURSE NAME: DETAILS OF CONSTRUCTION ESTIMATING COURSE NO: CE-200 Lecture 3 R.C.C WORKS Measurement of materials for cement concrete mixer: Accurate measurement of cement, fine aggregate and coarse aggregate is most necessary for producing good concrete. Cement: cement should always be measured by weight. Weight of 1bag cement = 50kg. 1 bag cement = 1.25cft Sand: sand should be measured by volume (cft or cum). Coarse aggregate: coarse aggregate may be measured by volume (cft or cum) Water: water is measured by volume. The strength and workability of concrete depend to a great extent on the amount of water used in mixing. Quality of water is measured by using water cement ratio. Water cement ratio = weight of water / weight of cement 1gallon = 4.546lit 1 lit = gallon Controlled concrete: A concrete mix which is designed on the basis of test of the strength conducted in the laboratory on the trial mixture of cement and aggregates to be actually used in the construction is termed as controlled concrete. Reinforcing bars: The most common type of reinforcing steel is in the form of round bars often called rebar s available in different diameters. These bars are furnished with surface deformations for the purpose of increasing resistance to slip between steel and concrete. For many years, bar sizes have been designated by no. (Say #3 bar) #3 bar means, diameter of bar = 3/8 inch. Bar no Area (in 2 Nominal weight ) inch mm lb/ft kg/m

19 Standard weight per meter in kg = D 2 /162 Where, D = dia in mm Concrete protection for reinforcement: To provide the steel with adequate concrete protection against fire and corrosion, the designer must maintain a certain minimum thickness of concrete cover outside of the outermost steel. The thickness required will vary depending upon the type of member and conditions of exposure. In general, the centre of main flexural bars in beams should be placed 2.5 to 3 inch from top or bottom surface of beam to furnish at least 1.5inch of clear cover for the bars and stirrups. In slabs, 1inch to the centre of the bar is sufficient to give the required 3/4inch cover. Bent up bar: The usual practice of bending of a bar near support is at an angle of The angle of bend may also be 30 0 in shallow beams where effective depth is less than 1.5 times its breadth. Purpose of bent bars: To resist negative moment this occurs at the regions of support. To resist shear force this is greater at the support. When Ө = 45 0, Sin45 0 = d/x X = 1.414d For bent bar extra length required = x-a = 1.414d d = 0.414d Total length = L + 2*0.414d When Ө = 30 0, Sin30 0 = d/x X = 1.732d For bent bar extra length required = x-a = 2d d = 0.27d Total length = L + 2*0.27d

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21 Detailed estimate of a R.C.C beam : Calculation of steel : 2-12mm straight, L = (in the wall)+6 (hook) = Total length = 2*10.67 = 21.34ft = 6.50m 2-19mm straight, L = Total length = 6.50m 2-19mm cranked, L = *0.42*(15-2*2.5) = Total length = 22.74ft = 6.93m For tie bar, L = 2*(10-2*1.5)+2*(15-2*1.5)+6 (hook) = 44 = 3.67 No of tie = 10*12/6 +1 = 21 Total length = 21*3.67 = 77.07ft = 23.50m Total 19mm bar required = ( )m = 13.43m = 30kg Total 12mm bar required = 6.5m = 6kg Total 10mm bar required = 23.50m = 15kg Calculation of concrete : Volume of concrete = 10*10/12*15/12 = 10.42cft

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23 Detailed estimate of a R.C.C column : Calculation of steel : For main bar: Length of main bar,l = (in the footing)+1 +6 (hook) = 16 No of bar = 4 Total length = 4*16 = 64ft = 19.51m For tie bar : No of tie =( (10 *12+4 *12)/6) +1 = 29 Length of one tie = 2*(10-1.5*2)+2*(12-2*1.5)+6 (hook) = 38 = 3.17 Total length = 3.17*29 = 91.93ft = 28.02m For base : No of bar in one direction = (4*12-6(clear cover))/6 +1 = 8 Length of one bar = 4-6 (cc)+6 (hook) = 4 Total length = 4*8 = 32ft Grand total = 32*2(for both way) = 64ft = 19.51m Total 20mm bar required = 19.51m = 19.51* *(20)^2 = 49kg Total 16mm bar required = 19.51m = 19.51* *(16)^2 = 31kg Total 10mm bar required = 28.02m = 28.02* *(10)^2 = 18kg Calculation of concrete : For column = 10*10/12*12/12 + 4*12/12*14/12 = 13cft For base = 4*4*12/12 = 16cft Total concrete required = 29cft.

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25 Detailed estimate of a R.C.C slab: Calculation of steel : Steel in long direction : c/c alt ckd : No of bar = (13 *12-(10 x 2)/6) + 1 = 24 Straight bar = 12, cranked bar = 12 Length of straight bar = 20-4 *2(wall) + 6 (hook) = Additional length required for one cranked = 0.42*4.5 = 1.89 Length of one cranked bar = *1.89 = Total length of straight bar = 12* = 238 ft = 73m Total length of cranked bar = 12*20.46 = 246 ft = 75m Steel in short direction : 10mm@5 c/c alt ckd : No of bar = (20 *12-(10 *2)/5)+1 = 45 Straight bar = 22, cranked bar = 23 Length of straight bar = 13-4 *2+ 6 = Length of one cranked bar = *1.89 = Total length of straight bar = 22*12.83 = 283 ft = 87m Total length of cranked bar = 23*13.15 = 303 ft = 93m For extra top : Long direction : L = (10 / /3)+6 (hook) = 6.33 Total length = 12*6.33 = 76 ft = 23.5m Short direction : L = (13 /3)+6 = 4.83 Total length = 2*(23*4.83) = 223 ft = 68m Grand total length of 10 mm bar = ( )m = 419.5m = 419.5* *(10)^2 = 260 kg Calculation of concrete (1:2:4) : Volume of concrete = 20*13 = 260 cft Amount of cement = 1/7*260*1.55 = cft = 46 bag Amount of sand = 2/7*260*1.55 = 116 cft Amount of khoa = 4/7*260*1.55 = 231 cft Summary : Cement = 46 bag Sand = 116 cft Khoa = 231 cft Steel(10 mm) = 260 kg

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27 Detailed estimate of a stair case : Calculation of steel : For 1 st flight : 12mm@4 c/c, L = (into the beam)+6 (hook) = No of bar = (4*12/4) +1 = 13 Total length(12mm) = 13*18.47 = ft = 73.19m In the bottom slab, 12mm bar, L= 3 +3 (hook) = 3.25 Total length (12mm)= 13*3.25 = 42.25ft = 12.88m In the 1 st landing, L= = 3.75 Total (12mm)= 13*3.75 = 14.86m 12mm bar in the bottom slab, L = = 4.50 Total length(12mm)= 13*4.50 = 17.83m 12mm bar in the landing slab, L = (hook)+7 (in the wall) = 7.33 Total length(12mm) = 29.04m 10mm binder: No of binder = (( )*12/7 )+1 = 49 Length of one bar = 4-6 (cc) + 6 (hook) = 4 Total length (10mm)= 4*49 = 59.74m For Landing beam : No of straight bar = 5, L = 8 Total length(16mm) = 5*8 = 12.19m Transverse bar : No of bar = (8*12/6)+1 = 17 L = 50 = 4.17 Total length(10mm) = 17*4.17 = 21.59m Grand total length of 12mm bar = ( ) = 147.8m = 132kg Grand total length of 10mm bar = = 81.33m = 51kg Grand total length of 16mm bar = 12.19m = 20kg For 2 nd flight: Same procedure Calculation of concrete : Waist slab = 2*9.72*4*6/12 = 38.88cft At bottom = 1*3.67*8*6/12= 14.68cft 1 st & 2 nd landing = 2*4*8*0.5 = 32cft Steps = 20*4*(1/2*0.83*0.5) = 16.6 cft Landing beam = 8*10/12*18/12 = 10cft Total amount of concrete work = cft

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29 Detailed estimate of a pile: Calculation of steel: No Description of item No of bar Length Total length (ft) L (m) 6-16mm dia bar mm@8 c/c 40*12/ 3.14*(20-3 ) = = 60 5 Unit weigh t (kg/ m) Total weight (kg) Calculation of concrete: Volume of concrete = 3.14*(20/12)^2*(1/4)*44.5 = 97cft.

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31 Detailed Estimate of a septic tank : Calculation of various items : No Description of item No L B H Quantity Unit 1 Earth cutting : Wall cft Tank cft Total Earth cutting = cft 2 Brickwork : Brick soling (under footing) sft On the floor sft Total Brick soling = sft Brickwor in supersturcture Long wall cft Short wall cft Partition wall cft Total = cft Deduction for opening cft Net total = cft Concrete work Footing cft At floor cft Top slab cft Beam cft Total = cft Plastering : 1/2" plastering Inside wall sft Outside wall sft Partition wall sft Total = sft 1/4"plastering At floor sft Top slab sft Calculation of steel in the wall : Short wall : For main bar : Length of main bar = (hook) = 11.5 No of bar = (10*12/5)+1 = 25

32 Total length = 2*25* 11.5 = m For two short wall = 2* = m For binder : L = 10 No of bar = ((8+2)*12/6)+1 = 21 Total length = 2*21*10 = 128m For two wall = 2*128 = 256m Long wall : For main bar : L= 11.5 No of bar = 33 Total length = m For two long wall = 463m For binder: L= No ob bar = 21 Total length = m For two wall = 340m Grand total 12mm bar required = = m = 724kg Grand total 10mm bar required = = 596m = 369kg

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34 Detailed estimate of a retaining wall: Calculation of steel: No 1 Description of item No of bar In the wall 19mm@16 c/c (30*12/ 16)+1 = 24 Length (ho ok) = Total length (ft) 24* = 426 L (m) Unit weigh t (kg/ m) Total weight (kg) mm@16 c/c * = mm@8 c/c mm@7 c/c 15*12/ = = 27 16mm@5 c/c mm@6 c/c Footing base 16mm@6 c/c 61*2 = mm@8 c/c 12*2 = Summary: Total 19mm bar = 670 kg Total 16mm bar = 1456kg Total 10mm bar = 312kg Calculation of concrete: Volume of concrete at foundation = 4*30*1.5 = 180cft Volume of concrete at wall = (1+2)/2*15*30 = 675cft Total volume of concrete = 855cft.

35 COURSE NAME: DETAILS OF CONSTRUCTION ESTIMATING COURSE NO: CE-200 Lecture 4 FOUNDATION Every building consists of two basic components: Superstructure Substructure Superstructure is usually that part of the building which is above ground and which serves the purpose of its intended use. Substructure is the lower portion of the building, usually located below ground level, which transmits the loads of the superstructure to the sub soil. Foundation: A foundation is that part of the structure which is in direct contact with the ground to which the loads are transmitted. The soil which is located immediately below the base of the foundation is called the sub soil or foundation soil. Footing: The lowermost portion of the foundation which is in direct contact with the sub soil is called footing. Functions of foundations: Reduction of load intensity: Foundation distributes the loads of the superstructure to a large area. So the intensity of load at its base does not exceed the safe bearing capacity of sub soil. Even distribution of load: Foundations distribute the non uniform load of the superstructure evenly on the sub soil such as combined footing. Provision of level surface: Foundation provide leveled and hard surface over which the superstructure can built. Lateral stability: It anchors the superstructure to the ground imparting the stability of the building against sliding & overturning due to horizontal forces. Safety against undermining: It provides structural safety against undermining or scouring due to flood water, borrowing etc. Protection against soil movement: Special foundation prevents the distress in the superstructure due to expansion or contraction of the subsoil because of moisture movement of soil. Essential requirements of a good foundation:

36 The foundation shall be constructed to sustain the dead and imposed load and to transmit this to the sub soil in such a way that the pressure on soil do not cause excessive settlement. Foundation base should be rigid so that differential settlements are minimized. Foundations should be taken sufficiently deep to guard the building against damage caused by swelling or shrinkage of sub soil. Foundation should be so located that its performance may not be affected due to unexpected future influence. Types of foundation: Shallow foundation Deep foundation Shallow foundation: When the foundation is placed immediately beneath the lowest part of the superstructure, it is termed as shallow foundation. A foundation is shallow if its depth is equal to or less than its width. There are various types of shallow foundations: 1. Spread footing 2. Grillage foundation 3. Eccentrically loaded footing 4. Combined footing 5. Mat or raft footing 6. Strap footing Spread footing: Spread footings are those which spread the super imposed load of wall or column over the widen area. Spread footing may be of the following types- (a) Wall footing: These types of footing consist of several courses of bricks. It might be two types: simple footing and stepped wall footing. In case of stepped footing, the lowest course is usually twice the breadth of wall above. The increase base width of the wall is achieved by providing 2.5in offset on either side of the wall. Depth of each course is usually 5inch. Generally a concrete base is provided at the lowest level. (b) Column footing: Column footing is one which is provided under a column for distributing the concentrated loads in the form of uniformly distributed load on soil below. Generally column footing means reinforced cement concrete column footing. It also may different types: Single footing: Here the column load is distributed through the single spread. Stepped footing: This footing is generally used for heavily loaded column which requires greater spread. Sloped footing: In this footing the concrete base does not have uniform thickness but it is made sloped with greater thickness at its junction with the column and smaller thickness at the ends.

37 (c) Reinforced concrete footing: In places where the walls are subjected to relatively heavy loading and the bearing capacity of the soil on which the wall footing is to rest is very low, the wall footing results a massive structure. In such case it is desirable to provide reinforced concrete footing below the wall. (d) Inverted arch footing: In older periods, this type of foundation used for multistoried buildings. These types of foundation greatly reduced the depth of foundation in soft soils. However with the advancement in engineering technique, inverted arch construction is rarely done these days. Grillage foundation: When heavy structural loads from superstructure are required to be transferred to a soil of low bearing capacity, grillage foundation is often found to be lighter and more economical. This avoids deep excavation and provides necessary area at the base to reduce intensity of pressure. Depending upon material used for construction grillage foundation can be divided in two categories: a) Steel grillage: Steel grillage foundation consists of steel beams also known as grillage beam. In this case excavations are carried to the desired depth and the bed is well leveled. This foundation bed is covered with a layer of rich mixture of concrete. This is well compacted so as to make the layer of concrete an impervious bed. Grillage beams of designed dimensions are then placed on this bed of concrete at specified distance apart using separators. The upper surface of grillage beam flanges is brought in a horizontal plane and rich cement grout is then poured all around the lower flanges of the beam. The concrete is then placed between and around the beam. b) Timber grillage: Where the soil encountered is soft and is permanently water logged building wall can be economically supported by suitable designed grillage foundation of timber. Eccentrically loaded footing: As far as possible, the foundation should be so shaped and proportional that the center of gravity of the imposed load is coinciding with the centre of gravity of the area of base. However when the wall or columns are to be placed closely to property lines, the required supporting areas of the base cannot be placed concentrically with the imposed load without overlapping the property line. In such case, the footing is so shaped as to have a considerable wider base with regular offsets on the inside while the outside wall face is kept flush with the boundary line. Combined footing: A spread footing which supports two or more columns is termed as combined footing. It may be following types: (a) Rectangular (b) Trapezoidal (c) Combined between wall footing The combined footing for column will be rectangular in shape if they carry equal loads. If the columns carry unequal loads, the footing is of trapezoidal shape. The design of combined footing should be done in such a way that C.G of column load coincides with C.G of footing area. Sometime it may require providing combined footing for column and a wall.

38 Mat or Raft foundation: A raft or mat is a combined footing that covers the entire area beneath a structure and supports all the walls and columns. When the allowable soil pressure is low or the building loads are heavy, the use of spread footings would cover more than one half the areas and it may prove more economical to provide mat or raft foundation. Also if the structure is liable to subsidence on account of uncertain behavior of its sub soil water condition, raft foundation should be preferred. Strap footing: If the independent footing of two columns is connected by a beam, it is then called strap footing. Strap footing may be used where distance between the columns is so great that a combined trapezoidal footing becomes quite narrow, with high bending moments. In that case each column is provided with its independent footing and a beam is used to connect the two footings. The strap beam does not remain in contact with soil and thus does not transfer any pressure to soil. Deep foundation: Deep foundation is those in which the depth of foundation is very large in comparison to its width. Situation for providing deep foundation: The load of the super structure is heavy and its distribution is uneven. The top soil has poor bearing capacity. The subsoil water level is high so that pumping of water from the open trenches for the shallow foundations is difficult and uneconomical. There is large fluctuation in sub soil water level. If deep strip foundation is attempted, timbering of sides is difficult to maintain or retain the soil of the sides of trench. The structure is situated on the sea shore or river bed, where there is damage of scouring action of water. Canal or deep drainage lines exist near the foundations. The top soil is expansive in nature. Types of deep foundation: 1. Pile foundation 2. Pier foundation / cofferdams 3. Caissons or well foundation Pile foundation: Pile foundation is generally used when simple spread foundation at a suitable depth is not possible either because the stratums of required bearing capacity or steep slopes are encountered. Depending upon their function or use piles may be classified in following types:

39 End bearing pile: End bearing piles are those which are driven into the ground until a hard stratum is reached. Such piles act as pillars, supporting the super structure and transmitting the load down to the level at which it can safely borne by the ground. Friction piles: When piles are required to be driven at a site where the soil is weak or soft to a considerable depth, the load carried by a pile is borne by the friction developed between the side of the pile and the surrounding ground. Sheet pile: Sheet piles differ from above piles is that they are rarely used to furnish vertical support but are used to function as retaining wall. Generally used as impervious cut off to reduce seepage. Anchor piles: When piles are used to provide anchorage against horizontal pull from sheet pilling wall or other pulling forces. They are termed as anchor piles. Batter piles: When piles are driven at an inclination to resist large horizontal or inclined forces, the piles are termed as batter piles. Fender piles: When the piles are used to protect concrete deck or other water front structure from the abrasion or impact that may caused from ships are called fender piles. Compaction piles: When piles are driven in granular soil with the aim of increasing the bearing capacity of the soil, the piles are termed as compaction piles. Tension piles: The piles that are used to anchor down the structures subjected to uplift due to hydrostatic pressure or due to overturning moment. Pier foundation: When a heavy loaded building is to be situated in sandy soil or soft soil, overlaying hard bed at responsible depth, pier foundation is used to transfer the load to the hard bed below. These methods consist of sinking vertical shafts up to hard bed and filling them with concrete. Cofferdams: A cofferdam may be defined as a temporary structure constructed in a river or lake or any other water bearing surface for excluding water from given site in order to perform various operation on dry surface. Types: Earthen cofferdam: It essentially consists of an earthen embankment built around the area to be enclosed. Rock fill cofferdam: If the depth of water to be retained by the embankment of cofferdam is of order of 1.8 to 3m, stone or rubble is used for the embankment. This is known as rock fill cofferdam. Single walled cofferdam: This type of cofferdam is used in places where the area to be enclosed is very small and the depth of water is more about 4.5to 6m. Doubled walled cofferdam: For cofferdam required to enclose large area, in deep water single wall type becomes uneconomical as larger sections would be necessary to resist water pressure. Double walled cofferdam is provided in such situations. Crib cofferdam: In deep water where it is difficult to penetrate the guide piles or sheet piles into the hard bed bellow, crib cofferdam is used. In this type, the sheet piles are supported by a series of wooden cribs. A crib is a frame work of horizontal timbers installed in alternate courses to form pockets which can be filled with earth or stones.

40 Cellular cofferdam: This type of cofferdam is mostly used for de watering large areas in places where the depth of water may be of the order of 18 to 21m. These are mostly used during the construction of marine structures like dams. Cellular cofferdam is made by driving straight web steel, sheet plates arranged to form a series of inter connected cells. The cells are constructed in various shapes. Finally the cells are filled with clay sand or gravel to make them suitable against various forces to which they are likely to be subjected to two common shapes of the cellular cofferdam are : Circular type and diaphragm type. Caissons: A caisson may be defined as a watertight structure made up of wood, steel or reinforced concrete for foundations of bridge, piers, abutments in rivers and lakes dock structure for shore protection. The caisson remains in its position and ultimately becomes an integral part of the permanent structure. Types of caissons: 1. Open caisson 2. Box caisson 3. Pneumatic caisson Open caisson: Depending upon their shapes, open caissons can be further classified as: Single wall open caisson: This is a box type structure having no top or bottom (during construction and mainly consists of vertical walls) Cylindrical open caisson (well): This may be defined as a cylindrical shell made up of timber, masonry, steel or reinforced concrete with a cutting edge which is sunk by excavating the soil with in the shell. To facilitate sinking of the caisson, water jets are sometimes used around the sides which decrease the skin friction. This caisson is also known as well caisson. Open caisson with dredging wells: This type of caisson has the distinction of being employed for the deepest foundation for bridge piers, abutments and other similar structure. The caisson in this case is rectangular or square in plan and is further subdivided into smaller section from inside forming open walls. The outside walls as well as the inside divider walls are normally made up of reinforced concrete. Box caisson: This type of caisson is similar to open caisson except that it is closed at the bottom. This caisson is cast and cured on the land and when required it is launched in water. The caisson is sunk by filling sand, gravel or concrete in the empty space inside. The function of the sand layer is to uniformly distribute the superimposed loads over the soil below the caisson and thus avoid tilting of caisson. Pneumatic caisson: This type of caisson is closed at top and open (during construction) at the bottom. The water is excluded from the caisson chamber by means of compressed air. Machine foundation:

41 Another type of foundation is used for machine. Design of this foundation involves careful study of the vibration characteristics of the foundation system. All parts of machine foundation should be designed for maximum stresses due to worst combination of vertical loads, torque, longitudinal and transverse forces, stresses due to temperature variation and foundation dead load. The foundation block should have the designed thickness and should be reinforced both at top and bottom even if reinforcements are not required from design consideration. Causes of failure of foundation: The causes of failure of foundations may be summarized under the following heads: 1. Unequal settlement of the subsoil. 2. Unequal settlement of masonry. 3. Horizontal movement of the soil adjoining the structure. 4. Shrinkage due to withdrawal of moisture from the soil below the foundation. 5. Lateral pressure tending to overturn the structure. 6. Action of atmosphere. 7. Lateral escape of the soil below the foundation.

42 COURSE NAME: DETAILS OF CONSTRUCTION ESTIMATING COURSE NO: CE-200 Lecture 5 BRICK MASONRY Definition: The construction carried out using bricks and mortar is known as brick masonry. Types of brick: 1. Traditional bricks 2. Modular bricks Strength of brick masonry depends on: Quality of bricks Quality of mortar Method of bonding used Unbounded wall, even constructed with good quality bricks and mortar has little strength and stability. Causes of preferring brick masonry over other types of masonry: 1) The bricks are of uniform size and shape. So they can be laid in any define pattern. 2) The art of brick laying can be under stood very easily and even unskilled masons can do the brick masonry. Stone masonry construction requires highly skilled masons. 3) Bricks do not need any dressing like stone. 4) Bricks are very light in weight and convenient in size. They can be easily handled. 5) As the bricks are light in weight, they do not require any lifting apparatus. 6) They can be manufactured at all sites and there is no problem of its availability. Also they do not require transportation from long distance. 7) Light partition wall and ornamental works can be easily constructed by brick masonry. Traditional bricks: The bricks that are generally used in construction are known as traditional bricks. General size of the brick is 9.5 x 4.5 x Modular bricks: Any bricks which are of same uniform size of PWD standard are known as modular bricks. Moulded bricks: Moulded bricks are those which are manufactured in special shapes and sizes to be used for giving architechtural shapes. Such bricks are used for cornices, slopping walls etc. Stretcher: A stretcher is the longer face of the brick. A course of brick in which all the bricks are laid is known as stretcher course if all the stretchers are on facing (9.5 x 2.75)