estimating & tendering. estimating work involves dealing with measurements and quantities...
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Estimating & Tendering
Estimating work involves dealing with
• Measurements and quantities• Pricing and rates• Subcontract packages• Tender preparation
Types of contract
-Lump Sum or Hard Money contracts-Cost plus %-age contracts-Cost plus fixed fee contracts
TERMINOLOGY
Provisional Cost sum, is a cost to supply and fix an item
Prime cost item, is the price for supply only
Example 1A $10 000 PC sum was allowed for A/C in the contract. The
actual cost ended up being $8 500, so the client gets a $1 500 refund.
Example 2A $10 000 PC sum was allowed in the contract. Actual cost was
$11 500. Charge the client the extra $1 500 plus your margin of say 10-%, a total of $1 650.
Example 3$35/m2 for a 100 m2 tiled floor was allowed in the contract. If
the tiles the client chose cost $30/m2, the client gets a refund of $5/m2 x 100 m2 = $500.
More Terminology
Client Contingencies: This is an amount set into the contract to cover an unknown amount of work. Say you allow $10 000 for excavating through rock. At the completion of the contract the contractor must accurately account for the actual costs and offset it against the allowance made.
Contractor Contingencies: Contractors can use contingency allowance for unknown events that they are contractually bound for. In this instance it covers the contractors risk and can be a %-age on the contract value and dependant on how risky you think the job is. If the contingency is not used, it is not returned to the client but increases the contractor’s profit.
Factors to consider when tendering- How much work have you already got on? Do you want or
need more work?- Can you handle more work and is it going to be profitable?- Are you technically and financially capable?- Who is the client or Architect? Good to work with?- How many tenderers are there likely to be?- Who is the main competition? Are they desperate for work?- What are your chances of success?
EARTHWORKSDemolition?Clearing and levelling the siteSetting out new buildingsExcavating for footings
Minor demolition example
Estimate:Machine hire: 20 hrs @ $60/hr = $1 200Labour: 1 person 20 hrs @ $25/hr = $500Truck hire: 15 hrs @ $50/hr = $750Dumping fees: 85 ton @ $8/ton = $680 Total = $3 130
Terminology
A Foundation is the prepared soil that you are going to start building on
A Footing is usually made from reinforced concrete and is the first thing you build upon that foundation
ESTIMATING SHEET
Project: Estimator:
Location: Extended
Date: Sheet No. of Form 1/A
Description Unit Quantity Rate Estimate
Example – raft slab footing5 x 5 m in plan with 500 x 300 mm beams around the perimeter
and a 100 mm thick slab. Edge rebate for brickwork.
86 100 120 150 500
300 150
TRENCHING incl edge formDescription Unit Qty Rate $Setting out: 1 person ½ day hr 4 30 120Backhoe 1 day hr 8 55 440Clear site to 150 mm m2 25 25 625Labour: 2 persons 1 day hr 16 30 480Spoil removal 6.8 m3 ton 11 11 121 Total to summary $1 786
CONCRETE placement and finishingDescription Unit Qty Rate $Labour 2 persons 1 day hr 16 30 480 Concrete pump* No. 1 350 350Vibrator (own) No. 1 - - Miscellaneous 100 Total to summary $930• Due to limited site access
Concrete supply m3 6 120 $720
Quantity of concrete (Use centre lines to measure) 5000 mm 5000 – 2 x 60 = 4 880 5000 – 2 x 150 = 4 700 5000 – 2 x 300 = 4 400 5000 – 2 x 350 = 4 300 86 100 120 150 500 Slab: 4.4 x 4.4 x 0.1 = 1.94 m3 Beam: 0.3 x 0.5 x 4.7 x 4 = 2.82 m3 Wedge: 0.15 x 0.15 x 0.5 x 4.3 x 4 = 0.19 m3 Rebate: -0.12 x 0.086 x 4.88 x 4 = -0.20 m3 4.75 m3 Add 20% 0.95 m3
5.7 m3 300 150 Say 6 m3
REINFORCINGDescription Unit Qty Rate $Reo bars 6 Y1620 lm x 6 + 20% lap/waste lm 144 2.80 403Ligatures pre-fab W10@ 0.6 m cts. 20/0.6 + 20% No. 40 2.50 100Fabric F72 to slab5 x 5 = 25m2 + 20% laps m2 31 5.50 171Chairs and ties item 1 50 50DPM 100 x 2 m roll No. 1 86 86 Total to summary $810
Labour 2 persons 1 day hr 16 30 $480
SUMMARYLabourTrenching $1 786Reo $480Concrete $930MaterialReo $810Concrete $720 Total $4 726
Example – CarpentrySay we have a four walled room 5 x 5 m with 2.7 m high walls.
All timber is 70 x 35 pine with studs at 600 mm c/c.
Description Unit Qty Rate $70x35 top and bottom plates lm 41 2.60 10770x35 studs [email protected] lm 103 2.60 26870x35 noggins [email protected] lm 21 2.60 54Damp Proof Course roll No. 1 21.50 22Nails and Dynabolts item 20First fix carpenters 2p x 2 day hr 32 35.00 1120Miscellaneous 100 Total to summary $1 691
How many bricks per square metre of wall?Standard brick size 230 x 76 mmMortar joints nominally 10 mm
Area taken up by one brick is 0.240 x 0.086 = 0.2064 m2We get 1/0.02064 = 48.45 bricks/m2
For small areas round off to 50/m2 and add a %-age for waste
Tendering process
- Ensuring that you are invited to tender, if that is limited- Taking the tender documents, which consist of drawing,
specifications and sometimes a bill of quantities, and breaking them down into packages. These packages must be appropriate for your subcontractors to bid for.
- Inviting subcontractors to bid and evaluating the bids.- Adding up all construction costs plus the preliminaries or
overheads plus your margin to form the tender price.- Finally, you need to submit the tender as per the instructions,
and don’t be late!
