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Estimating Tendering

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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 1
A $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 2
A $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?
EARTHWORKS
Demolition?
Clearing and levelling the site
Setting out new buildings
Excavating for footings
Minor demolition example

Estimate:
Machine hire: 20 hrs @ $60/hr = $1 200
Labour: 1 person 20 hrs @ $25/hr = $500
Truck hire: 15 hrs @ $50/hr =        $750
Dumping 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 footing
5 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 form
Description                   Unit   Qty   Rate      $
Setting out: 1 person ½ day    hr     4     30      120
Backhoe 1 day                  hr      8    55      440
Clear site to 150 mm           m2     25    25      625
Labour: 2 persons 1 day         hr    16    30      480
Spoil removal 6.8 m3           ton    11     11      121
              Total to summary                    $1 786
CONCRETE placement and finishing
Description                  Unit Qty   Rate $
Labour 2 persons 1 day         hr  16    30 480
Concrete pump*                No.   1   350 350
Vibrator (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
REINFORCING
Description                   Unit Qty    Rate   $
Reo bars 6 Y16
20 lm x 6 + 20% lap/waste      lm   144   2.80 403
Ligatures pre-fab W10
@ 0.6 m cts. 20/0.6 + 20%       No. 40    2.50 100
Fabric F72 to slab
5 x 5 = 25m2 + 20% laps        m2    31    5.50 171
Chairs and ties               item   1     50    50
DPM 100 x 2 m roll              No.   1     86 86
                Total to summary               $810

Labour 2 persons 1 day        hr    16     30    $480
SUMMARY
Labour
Trenching      $1 786
Reo              $480
Concrete         $930
Material
Reo              $810
Concrete         $720
          Total $4 726
Example – Carpentry
Say 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   107
70x35 studs 38@2.7               lm 103       2.60  268
70x35 noggins 4@5.1              lm   21      2.60   54
Damp Proof Course roll           No.   1     21.50   22
Nails and Dynabolts              item                20
First fix carpenters 2p x 2 day   hr  32     35.00 1120
Miscellaneous                                       100
                  Total to summary                $1 691
How many bricks per square metre of wall?
Standard brick size 230 x 76 mm
Mortar joints nominally 10 mm

Area taken up by one brick is 0.240 x 0.086 = 0.2064 m2
We 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!

				
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posted:12/5/2011
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