Estimating & Tendering

1. Estimating & Tendering

2. Estimating work involves dealing with • Measurements and quantities • Pricing and rates • Subcontract packages • Tender preparation

3. Types of contract Lump Sum or Hard Money contracts Cost plus %-age contracts Cost plus fixed fee contracts

4. TERMINOLOGY Provisional Cost sum, is a cost to supply and fix an item Prime cost item, is the price for supply only

5. 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.

6. 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.

7. 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?

8. EARTHWORKS Demolition? Clearing and levelling the site Setting out new buildings Excavating for footings

9. 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

10. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. SUMMARY Labour Trenching $1 786 Reo $480 Concrete $930 Material Reo $810 Concrete $720 Total $4 726

18. 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

19. 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

20. 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!