COST ESTIMATE GUIDELINES AND REFERENCES How to Avoid Bidding Errors A. Read thoroughly plans, specifications, and general conditions of contract, addendums, and invitation to bid. Study carefully the following terms and conditions. 1. Bid bond – 5% to 10% Cash or manager’s check 2. Time of completion – number of working days or calendar days 3. Performance bond – all risk insurance 10% to 20% of contract. a. Work Guarantee Bond – 20% to 30% of contract 4. Construction Bond for Residential – Subdivision Requirements 5. City Tax or Contractor’s Tax 6. Contractor’s insurance – Verify approved insurance company 7. Liquidated damages for 1% of 10% of bid 8. Price Escalation/ Time Extension 9. Revisions, changes, extra works 10. Last minute addendums, bid bulletins, time and date of the bid submission 11. Owner-supplied materials 12. Terms of Payments – Check Dpayments 13. Permits Construction Permits (Architectural, Structural, Plumbing, Mechanical & Electrical Occupancy Permits Demolition & sidewalk Permits City tax new codes 14. Building Code Requirements/Boundaries 1
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COST ESTIMATE GUIDELINES AND REFERENCES
How to Avoid Bidding Errors
A. Read thoroughly plans, specifications, and general conditions of
contract, addendums, and invitation to bid. Study carefully the following terms
and conditions.
1. Bid bond – 5% to 10% Cash or manager’s check
2. Time of completion – number of working days or calendar days
3. Performance bond – all risk insurance 10% to 20% of contract.
a. Work Guarantee Bond – 20% to 30% of contract
4. Construction Bond for Residential – Subdivision Requirements
5. City Tax or Contractor’s Tax
6. Contractor’s insurance – Verify approved insurance company
7. Liquidated damages for 1% of 10% of bid
8. Price Escalation/ Time Extension
9. Revisions, changes, extra works
10. Last minute addendums, bid bulletins, time and date of the bid
submission
11. Owner-supplied materials
12. Terms of Payments – Check Dpayments
13. Permits
Construction Permits (Architectural, Structural, Plumbing, Mechanical &
Electrical
Occupancy Permits
Demolition & sidewalk Permits
City tax new codes
14. Building Code Requirements/Boundaries
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B. Look for confusing requirements or any discrepancies in plans
and specifications. Refer to architect and owner in writing ( black & white)
C. Look for notations on plans – general scope of work, changes,
alterations, impossible requirements, Building code requirements
D. Evaluate & study carefully specifications
1. Make list of trades, brand, type that can fulfill the contract
2. Subdivide each trade list if needed
3. Ask quotations from subcontractors
4. Electrical, plumbing and mechanical if required.
Make sure you know the subcontractor suppose to quote on you. Set forms
to avoid gaps and mistakes
E. Set procedures for preparing bids
1. Plan the bid like a project with checklist, target date and project checklist
2. Check if bid required itemized cost breakdown/ unit cost of materials.
F. Check and double check take-off estimate. It might have been
overlooked. Spot check subcontractor proposals if complete. Take note of scope
of works. Verify items not included, unit cost of materials.
G. Site inspections – Verify thoroughly the following conditions.
1. Existing facilities to be demolished – wood, concrete steel.
2. Hauling In/ Out of matls– Disposal of debris. Location. Tools and
Equipment to be Used
3. Sources of Materials – Verify materials unit cost of nearby suppliers.
Major materials from existing supplier and minor materials from new supplier.
Verify terms of payment. Prepare materials checklist. Always check Current
Cost of materials, prepare checklist.
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4. Geographical conditions of site. Slopes, verify on plans, if backfilling is
required. Check if adobe, soil of backfill. Note depth of excavation requires.
Hauling in/out of backfilling, Dumping of debris from site.
5. Ideal location of bunkhouse, temporary warehouse or storage.
Temporary utilities. Dumping of materials to site must not have conflict with
the layout of proposed building.
6. Sources of manpower, technical expertise, tools and equipment
7. Temporary facilities- power, water, telephone
8. Future tapping of the following:
- Power
- Water
- Telephones
- Sewer and Drainage
Verify if in conformity with the plans. Check utility company
requirements. Project Study. Roads, sidewalks to be demolished.
Permits and payments.Deposits c/o Owner
H. Use the “RULE OF THUMB” method. Check the most contentious
items of bid. Recheck addition of subcontractors.
I. Analyze the bid even if it is not successful. Update cost of
materials. Check file records and other historical data. Get result of bidding and
prepare feedback for future references.
J. Major error in bid. Determine whether or not to continue work on the
project. Determine if you are willing to live with the error. Know the bid of other
contractor.
K. Take note of indirect cost, VAT and other government taxes and
requirements.
Subdivision requirements, construction bonds, insurance, city tax, performance bond.3
L. You may wish to withdraw the bid.
Reminders before Estimating
A. Read first plans, specifications and general conditions of contract to familiarize
yourself with the general scope of works.
B. Spot check nebulous requirements if available in local market. Verify if imported,
suppliers, type of materials
C. Rough estimate to try. It must be 30-50% of what might be the ultimate cost.
D. Preliminary estimate. Unit cost obtained from past project. Recheck verify current
unit cost.
E. Always use the rule of thumb in the final estimate
F. RE-check your estimate. Let someone do it. Spot check multiplications and
additions of subtotal
G. Ask for quotations of suppliers or subcontractors of specialty works
H. Use different techniques in estimate
1. By volume method
2. BY area method – sq. m.
3. By direct count
Be systematic. Breakdown estimate or use the area method.
Schedule organized breakdown.
I. Begin estimate with fresh mind. Difficult items first, easy items like addition of total
cost can be done when you are tired
J. Always use your imagination, observation, take note of items lacking or errors in
plans and specifications. Do not leave items. Immediately look for unforeseen
requirements before continuing to other portion.
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Estimate Checklist
A. Site Development/General Requirements
1. Mobilization/Temporary facilities
a. Temporary Fence – Total linear meter
Sawali 4’ x 5’ or GI sheets
Coco lumber – 2x3/2x4
C.W. nails
Check if corr. GI sheet temp. fence
2. ID / Uniforms/ Biodatas
3. Workers Quarters – Verify number of workers
a. Temporary Field Office
Plywood
2 x 4 lumbers
Roofing G.I. sheets or Lona – 20’ x 40’
Emergency Kit
Drums
Tools and Equipment
b. Temporary Power, Water and Telephone – Cost of utilities
during construction. Contractor or Owner
B.1 Checklist Temporary Power (Residential Only)
Description Qty Unit Unit Cost
RSC pipe ½ x 10’ 1 PieceEntrance Cup ½ 1 PieceRSC Conduit NippleSafety Switch 60 A 2p 1dia 1 SetTHW wire # 12 (5.5 mm²) 1 RollElectric Tape (big) 1 RollOne way switch 2 PieceDuplex Convenience Outlet 2 Piece
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Fluorescent 40 w 2 PieceMeter base 1 Set4 X 4 X 8’ coco lumber or equal
1 Piece
B.2 Temporary Toilet/Waterlines/Sewer
Description Qty Unit Unit Cost
PVC pipe 3”ρ x 10’ 2 PiecesPVC wye 3 x 3 3 PiecesPVC bend 4 PiecesPVC bend 2 PiecesPVC Cement 100 cc 1 QrtG.I. pipe ½ x 20’ 2 PiecesG.I. tee ½ 4 PiecesG.I. Elbow ½ 4 PiecesTaplon Tape 3 RollsFlush Type Water Closet 1 SetDrums 3 SetWater Hose ¾” x 15 lm
B.3 Checklist of tools and equipment to be used
Concrete Mixer (1 bugger)
Bar Cutter/Circular Cutter or Hacksaw Blade
Shovel
Pick Mattock
Leveling Hose
Bareta/Pointed bar
Angle Grinder
Vibrator
Compactor
Plastic Container
B.4 Manpower Transportation/Cash Advance for Mobilization
B.5 Temporary Bunkhouse for Workers and Storage of Materials
B. Siteworks
1. Demolition of Existing Structure
2. Hauling out/in
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Verify the following:
a. Slab, beams, footing, etc.
b. Materials that can be utilized – wood/steel/doors/etc.
c. Hauling out of usable materials and debris (labor+delivery
Description Capacity Unit Cost6 wheeler truck 2-4 m310 wheeler or dump truck 12-14 m3
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For one bag of Cement = 40 kgs (weight)
Gravel
G – 1 ¾ “ to 1 ½” gravel for foundations
Slab on fill
¾ gravel – 3/8 to 3/14” for all structural members
verify if crushed gravel or washed gravel
D. Formworks
1. Estimate form lumber using 2x3/2x4/2x6 coco lumber per total volume of
concrete to be used. Estimate first total concrete volume as per guidelines.
Coco lumber supplier – to order coconut bark, avoid lumber at center
2 x 3 / 2 x 4 - for vertical lateral ties and braces
2 x 6 - for beam support and footing
cost of coco lumber 12.5 to15.50 per bd. Ft.(jan ’06)
2. Normal coco lumber requirements
150 board feet per cubic meter of concrete
1 truckload of coco lumber – Elf, -1,800 to 2,500 bd. Ft.
Ten-wheeler -4,000 to 5,000 bd. Ft.
Cost of cocol umber 6.50 to 7.50 per board foot
3. Assorted C.W. Nails
C.W. nails 1 ½ “C.W. nails 2”C.W. nails 3”C.W. nails 4”
For scaffoldings
Commercial Sizes
1 box = 20-25 kgs (small)
1 box = 30-38 kgs ( large)
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Estimate Guide : 1 kilo per 50 board foot or lumber
QTY = Total board foot / 50 = N o s. of kilos / 25 = No. of
box
50 bd. Ft. 25 or 38 kgs/box
4. Concrete Nails – 3 “ & 4” for CHB filing guide, concrete walls ceiling joist
and cabinet frames. Quantity depends on the actual requirements
NAILS CHART
CW Nails Pieces per kilo Usage2D 1” 1,680 pcs Forms Plywood4D 1 ½” 705 pcs Forms plywood6D 2” 380 pcs T & G flooring8D 2 ½” 260 pcs Ceiling joist10 D 3” 120 pcs Trusses/Rafters20 D 4” 55 pcs Floor Joist
Finishing nailsSize Usage1” ceiling1 ½ “ T & G flooring2” Cabinet frames
5. PLYWOOD - Use 3/8” to ½” plywood. Normal market/commercialize of ¼ is too thin
Solve for Contact Surfaces. Columns/Beams/slabs as per plan. See checklist for concrete works.
Column Example: 4 sides or Perimeter(.20 + .20 + .40 + .40) x height = sq.m.
Beam Example 3 sides(.15 + .40 + .15) x height = sq.m.
Slab = Length x Width = Sq.m.
Summarize all required formworks
Total Contact Surface in Sq. Mts. = Nos. of Pieces
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area required for formsa
area required for formsa
2.88 or 1.20 x 2.42 Plywood Size of Plywood Required Note : Check if you can use it again if building is large. Small buildings assume as per estimate. Formoil – Normally to use USED oil – Quantity approximate; 1 ltr. per 15 sq. mts.
If steel scaffolding is to be used check rental per day of steel accessories. Verify to supplier.
Note : For residential, use good lumber for scaffolding, to be used later for rafters, purlins, ceiling joist, etc.
E. Steel Reinforcement/BarsSteel forms – rental per piece /day. As per plan
REBARS DESIGNATIONAmerican Society for
Testing Materials (ASTM)
Philippine Standard
Yield Point Strength
Tensile Strength
Usage
Kgs/ mm2
Psi Kgs/ mm2
Psi
Structural Grade
Grade 230
24.452 33,000 39.77 55,000 For residential only
Intermediate Grade (Grade 40)
Grade 275
28.042 40,000 48.95 70,000 Depend on structural design
Grade 60 Grade 410
41.80 60,000 63.22 90,000 For high-rise building
Standard Length of BarsFeet Meter Most commonly used available in hardware
6.00m20’ 6.00 m Special Length, per order to supplier26’ 7.50 m30’ 9.00 m35’ 10.50 m40’ 12.00 m
Commercial Sizes9 mm (2.3 kgs)10 mm (standard) 3/8 # 3 0.616 0.1112 mm (standard) ½ # 4 0.888 0.1216 mm (standard) 5/8 # 5 1.579 0.3120 mm (standard) ¾ # 6 2.466 0.4425 mm (standard) 1” # 8 3.854 0.7928 mm (standard) 1 1/8 # 9 4.83332 mm (standard) 1 ¼ # 10 6.313
Example:
20 pcs – 16 mm dia. X 6.00 bars20 x 1.576 x 6.0 = 189.46 kgs.
To get quantity of G.I. wire # 16
a. G.I. wire # 16, through use of Concrete Volume
2 kilograms per cu. m. of concrete = NO. OF ROLLS25 – 30 kilos per roll (Check commercial weight to supplier)
b. Estimate thru Rebars
20 kilos of G.I. wire per metric tons1 metric ton = 10,000 kilos1 kilo of wire = + 53 linear meter1 roll = 35-40 kilograms
or current commercial kilos per roll = 38 kgs/roll
c. G.I. wires for CHB walls4” chb - 10” length of tie wires5” or 6 “chb - 12” length of tie wiresSpacing of rebars
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Vertical @ 0.60 m. o.c.Horizontal every third layer
GI wires Kilos per sq. mts – 0.04
Example : Total Area of CHB walls – 230 m2 x 0.04 = 9.2 kilos, or 10 kilos of G.I. wire # 16
d. Welding Rodse. Rust Proofingf. Post Tensioning – per plan special Construction, quotation per suppliers
Rebars substitution
Say 12-16 Ø To 20 mm Ø
Reinforcement/Rebars DataHow to Determine Bar Splicing LengthType Minimum Splice Length1. Tension Bars 25 x bar size +150 mm2. Compression Bars 20 x bar size + 150 mm
Example : Column 20 mm = 20 x 20 mm + 150 mm
Compression = 550 mm or .55 m
NO FOOTING SHALL REST ON FILLING MATERIALS“Y” – spacing of bars 1 @ 0.05 2 @ 0.10
2. CHB PlasteringRatio 1: 2 or 1 part cement to 2 part sand
Cement½ - ¾ “ thk plastering
0.50 bags per sq. m.
Sand 0.057 cu. mts per bag
Example:
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Say, 200 sq. m x 2: both face--------------------------------
0.50= 200 bags cement
200 x 0.057 = 11.4 says, 12 cu.m.
3. CHB Type/ Strength
NLB or non load bearing 400-500 psi Available in local market
LB or Load Bearing (Jackbuilt), etc. 700-1000 psi Locally available special
chb
Note : Verify delivery cost within Metro Manila or outside Metro Manila
4. Floor Topping
Mortar Per cu.m . Volume Sand UsageClass A 1:2* 16 bags/cu.m. 0.80 cu.m. For topping,
finishing works, tiles,
etc.Class B 1:3** 12 bags/ cu.m. 0.89 cu.m For topping
over slab to level flooring after pouring
*1:2 Ratio 1 part cement for every 2 part sand** 1:3 Ratio 1 part cement for every 3 part sand
5. Rebars for CHB
4” chb 10 mm diameter at every 3rd layer horizontal bars10 mm diameter at 0.80 m vertical bars
6” chb 12 mm diameter at every third layer horizontal bars12 mm diameter at 0.80 m. vertical bars
Assume : 4.25 LM per sq.m. of chbSay : 210 sq.m. x 4.25 lm
= 892.50 LM---------------------------
6.00 m: standard length of bars= 148.75 pieces,
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say 150 pieces – 10 mm dia.x 6.0 m def bars
6. G.I. wire Masonry works Ga # 16
Tie Wire 10” to 12“ length. Included in rebars wire computation (see checklist)
7. Firewalls/ Toilets. Floor Toppinga. Requirement for waterproofing
Sahara Compound – 1 pack per bag of cement for plastering of firewalls
b. Plaster Board –. Assume 5 sq. meters per gallons for floor topping
G. Steel Trusses. Verify details as per plan.1. Type of trusses
Steel trussesOpen Web Rigid Frame Built Up
2. Checklist for Estimate per Plan. Always verify if roof framing is correct/ economical. Angular Bars
Top and bottom chordsWeb MembersCross BracingTurnbucklesBaseplate (Thickness)Bolts and nutsSag rodHanger or support for ceiling with boltsWelding rodOxygen AcetyleneC Purlins 2 x 4/ 2 x 6 1.5 mm thicknessAngular bars for fascia board connection
* Preferable to get quotation from qualified subcontractor
Wooden Trusses. Checklist per plan
Top Chord/ Bottom Chord
Web Members/ Collar Plate/ Struts
Wood Plate
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Girters
Fascia Board – Tanguile KD S4S
Wood Braces
Purlins
Machine Bolts, nuts and washers
Eaves ventilation – wood slots with US Aluminum Screen
Tension Rod and Sag Rods
Special Trusses – Fabricated for Low Cost Gang nail/Others
To get board foot of lumber
Example:
1 pc 2 x 3 x 16 2 x 3 x 1612
1 pc 8 bf/pc8 bf
5 pcs 2 x 5 x 14 2 x 5 x 1412
11.66 bf x 6 pcs58.33 bf
6 pcs 1 ½ x 2 x 14 1.5 x 2 x 1412
3.50 bf / pc x 6 pcs21 bf
Conversion FactorsCu.ft x 0.02832 Cu. mts.Bf ft. x 0.0833 Cu. ft.Cu. mts x 35.314 Cu. ft.Cu. ft x 2.8317 x 10-2 Cu. mts.
H. Roofing Works
Ordinary Corrugated GI sheet Ga.# 16
Standard Market Sizes Width Standard Length
Corr. GI sheet Ga # 26 x 32” Standard 7 feet-do- 8 feet-do- 9 feet-do- 10 feet-do- 12 feet
0.30 meters – standard overlap
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1 1 . 5 0 0.70 side lapped 2 ½ “
or 2 corr.
= 16.42, say 17 pcs. X 2 side
= 34 pieces Ga# 26 x 32 x 10’ Corr GI sheet
5.40 m. = 18’ 2 pcs.- 10’ length
2. Plain GI sheet Ga. # 26 x 32” x 8’
standard. Solve for flashing and counter flashing for firewalls and parapet. Verify actual
plan.
3. G.I. gutter Ga. # 26 x 8’ -
Standard Gutter
- Special Gutter ( Spanish type)
4. Ridge Rolls x 8’
5. Valley gutter. Verify if outside gutter or
inside gutter
6. Others per plan. To include fascia board
for estimate.
7. Accessories
a. GI roof nails 3 ½ “ - kilos
b. Lead Washer - kilos
c. GI washer ( medium or thick)- kilo
d. GI rivets ¼ x 3/16
e. GI strap Ga # 26
f. Nicolite Bar
g. Muriatic Acid
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h. Roof Cement ( Vulcanized)
i. Red Oxide or red lead primer
j. Silicon Sealant
For Color roof – Verify type to be used. Ask for quotation of supplier. Standard Sizes Brochures
Type 1 – Rib type long span ; most common for residential
ChecklistGa. # 26 (Thickness)
Width Length
a. 0.40 mm X 1.040 m X ___ LM Rib Type roofb. 0.40 mm X 0.610 m X 2.44 S type gutterc. 0.40 mm X 0.610 m X 2.44 V type gutter – valleyd. 0.40 mm X 0.610 m X 2.44 Ridge rolle. 0.40 mm x 0.915 m x 2.44 Capping/Flashing
Accessories
a. Tek Screw (Metal Screw) 12 pcs per sq m
b. Blind Rivets
c. Silicon Sealant Per tube
d. Touch Up Paint
e. Vulcaseal – gallon
Take note of delivery charge – Around P 2,000.00 – 2,500 per trip, within Metro Manila or
outside Metro Manila
Order roofing one month in advance. Delivery is 2 – 3 weeks after order and payment.
Always estimate as per actual plan.
Formulas
A2 = c2 – b2
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B2 = c2 – a2
C2 = a2 + b2
Roofing by area methoda. Determine total flat area required
L x W + pitch factor solve for linear feet requiredRoof pitch Add to total flat area