Chapter 7 Estimating Plumbing, HVAC, and Electrical Work

1. Chapter 7Estimating Plumbing, HVAC, and Electrical Work

2. Introduction • Estimates of large and/or complicated projects are prepared by specialists in these trades. • The ability to compile a takeoff of plumbing, HVAC, and electrical work can also be a useful skill for the builder’s estimator who sometimes needs to put together a quick price for these trades on a small job. • Also, some builders like to develop their own cost estimate for each trade’s scope of work to ensure that the quotes received are reasonable.

3. Measuring Generally • Little information about the plumbing, HVAC, and electrical systems is shown on the project plans of small jobs. • The estimator may need to draw sketches to be able to assess the layout of systems for a house. • These sketches can then help the estimator evaluate measurements such as the length of pipes for water supply and sewers on the job.

4. Measuring Plumbing (1 of 3) • Connecting water lines to main are enumerated. • Water and sewer pipes are described and measured separately in linear feet. • Fittings and valves are described and enumerated. • Hangers and supports are described and enumerated.

5. Measuring Plumbing (2 of 3) • Fixtures and equipment are described and enumerated, including: • Water meters • Gas meters • Water heaters • Lavatory basins • Water closets • Sinks • Laundry tubs • Bath tubs

6. Measuring Plumbing (3 of 3) • Items supplied by the builder and installed by the plumber are described and enumerated separately, including: • Refrigerators • Garbage disposal equipment • Dishwashers • Gas line piping is described and measured in linear feet. • Permits for the work are described and enumerated. • Pipe insulation is described and measured in linear feet. • Cutting, drilling, and patching required for this work are described and enumerated.

7. Measuring HVAC Work (1 of 2) • Ductwork is described stating the size and it is measured in linear feet. • Range, cooktop, laundry, and bath venting are described stating the size and it is measured in linear feet. • Fittings, hangers, and sleeve frames are described and enumerated. • Mechanical equipment is described and enumerated, including: • Air handling units • Furnaces • Heat exchangers • Etc.

8. Measuring HVAC Work (2 of 2) • Control wiring is described and measured in linear feet. • Low voltage wiring is described and measured in linear feet. • Electric and electronic controls are described and enumerated. • Testing and balancing are each measured as items. • Permits for the work are described and enumerated. • Duct insulation is described and measured in square feet. • Cutting, drilling, and patching required for this work are described and enumerated. • Cleanup resulting from this work is measured as an item.

9. Measuring Electrical Work (1 of 2) • Wire, cable, and conduits are described and measured in linear feet. • Cable tray and bus duct systems are described and measured in linear feet. • Hangers, sleeves, and supports are described and enumerated. • Electrical equipment, fittings, and fixtures are described and enumerated, including: • Fire alarm systems • Security systems • Communication systems • Etc.

10. Measuring Electrical Work (2 of 2) • Installing appliances is described and enumerated, including: • Cooktops • Microwave ovens • Built-in ovens • Range hoods • Permits for the work are described and enumerated. • Testing and hot checking the entire system is measured as an item. • Fire stops and flashings are described and enumerated. • Cutting, drilling, and patching required for this work are described and enumerated. • Cleanup resulting from this work is measured as an item.

11. Estimating Shortcuts • Instead of a full takeoff on many plumbing, HVAC, and electrical, estimators use shortcuts to compute their prices for the work. • With plumbing, HVAC, and electrical trades, a price per square foot of gross floor area could be used to provide a rough estimate of the cost, but more accuracy may sometimes be required.

12. Quick Estimates of Plumbing Work • A quite accurate estimate for plumbing work can be obtained quickly by means of a unit price for each plumbing fixture. • Enumerating fixtures and multiplying by the applicable price for each fixture can give an accurate price for the complete plumbing work. • Additional prices may be required for installing appliances, special fixtures, and any out-of-the-ordinary plumbing work.

13. Plumbing Example • Estimate the price of a three-fixture bathroom based on the following prices for the fittings involved: • 1 bathtub 72” x 36” - $2,425 • 1 water closet - $1,450 • 1 lavatory basin 19” x 16” - $845 • $4,720 • Extra for pipe and fittings 30% $1,416 • Total $6,136

14. Quick Estimates of HVAC Work • HVAC work can be estimated quite quickly by using a combination of prices per unit area and unit prices for items of equipment. • To estimate the total cost of ductwork, multiply the unit price from a past project by the gross floor area of the new house. • To complete an HVAC estimate, determine how many items of equipment are required, and multiply by the appropriate item price for each item.

15. HVAC Example • Estimate the price of a 2,200-square feet house with a special humidifier and exhaust fan: • Basic HVAC 2,200 SF at $4.25/ SF $9,350 • Humidifier $2,000 • Exhaust Fan $250 • Total: $11,600

16. Quick Estimates of Electrical Work • Electrical work can also be estimated quickly by means of a combination of prices per unit area and prices for items of equipment and fixtures. • For power wiring and fittings, multiply the number of power outlets by inclusive price per outlet. • For equipment and fixtures, multiply number of each item by unit price for that item, including: • Electrical panels • Sub-panels • Light fixtures • Etc.

17. Electrical Example • Calculate the electrical price for a 2,200-square feet house including a security system with motion detectors: • Basic electrical: 2,200 SF at $6.75/ SF $14,850 • Add security system $2,500 • Total: $17,350