ESTIMATING PLUMBING, HEATING, VENTILATING, AND AIR CONDITIONING (HVAC), AND ELECTRICAL WORK

Transcription

1 C H A P T E R 7 ESTIMATING PLUMBING, HEATING, VENTILATING, AND AIR CONDITIONING (HVAC), AND ELECTRICAL WORK OBJECTIVES After reading this chapter and completing the review questions, you should be able to: Explain why it is useful for the building estimator to be able to prepare a takeoff of plumbing, heating, ventilating, air conditioning (HVAC), and electrical Explain why it is useful for the building estimator to be able to make sketches of plumbing, HVAC, and electrical requirements for a project. Describe how plumbing, HVAC, and electrical work are measured in a takeoff. Explain how the builder s estimator can price the plumbing, HVAC, and electrical Explain the use of quick methods of estimating plumbing, HVAC, and electrical Describe the cost per fixture method of estimating plumbing. KEY TERMS backflow preventer duplex houses electrical estimating heat exchangers HVAC plumbing 143

2 144 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK Introduction Plumbing, heating, ventilating, air conditioning (HVAC), and electrical work are invariably performed by subcontractors on residential projects, but these trades represent a significant part of a project, usually accounting for more that 30 percent of the total project cost. It is, therefore, useful for the builder s estimator to be able to check trade quotes to ensure that they cover the full scope of work for that trade. Certainly estimates of large and/or complicated projects call for the expertise of specialists in these trades. Like any other estimators, those working on plumbing, HVAC, and electrical work need a thorough knowledge of how the work is done in that trade before they can assemble accurate quotes for the To be accurate, the prices for these quotes will have to be estimated using the same meticulous method used by building estimators with their That is, first prepare an accurate takeoff of the work items, then, by means of unit prices, calculate the anticipated cost of these items of 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 project. Indeed, some builders like to develop their own cost estimate for each trade s scope of work to ensure that the quotes received are reasonable; takeoff skills are definitely an asset if this analysis is to be done properly. Below we have identified the main items of work and how they are measured in a takeoff for each of these trades. Plumbing Work Generally On small residential projects, such as single houses and duplex houses, it is unusual to see much information about the plumbing system on the project plans other than, perhaps, the location of the main plumbing vent and basement floor drains. Lacking details from the plans, the estimator often has to draw sketches to be able to assess the plumbing layout 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 project. Measuring Notes Plumbing Work Water Distribution 1. Enumerate connections of water lines to the main. 2. Describe and measure hot water and cold water pipes in linear feet. 3. Describe and enumerate fittings and valves. 4. Describe and enumerate hangers and supports for pipes. Sanitary Sewer Pipes and Fittings 5. Describe and measure pipes in linear feet to 5 feet from the building. 6. Describe and enumerate backflow preventers, cleanouts, floor drains, roof drains, valves, and fittings. 7. Describe and enumerate hangers and supports for piping. Fixtures and Equipment 8. Describe and enumerate fixtures and equipment, including: a. Water meters b. Gas meters c. Water pressure reducing valves d. Water heaters

3 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK 145 e. Pumps f. Lavatory basins g. Water closets h. Bidets i. Sinks j. Laundry tubs k. Bath tubs 9. Describe and enumerate separately equipment supplied by the builder and installed by the plumber, including: a. Refrigerators b. Garbage disposal equipment c. Dishwashers Gas Lines 10. Describe and measure in linear feet gas line piping from the gas meter to all terminal points. 11. Describe and enumerate fittings and valves. 12. Describe and enumerate hangers and supports. Miscellaneous Plumbing Items 13. Describe and enumerate permits for the 14. Describe pipe insulation and measure in linear feet. 15. Describe and enumerate pressure testing of lines. 16. Describe and enumerate cutting, drilling, and patching required for this 17. Measure cleanup resulting from this work as an item. HVAC Work Generally Often the only HVAC information provided on plans of small residential projects is only the location of the furnace. So, before the estimator is able to takeoff this work, she/he needs to determine the position of heating ducts, air outlets and inlets, and thermostats. An outline of the location of ductwork sketched on the floorplans is useful for this purpose. Measuring Notes HVAC Work Ductwork and Venting 1. Describe ductwork, stating the size and measure in linear feet. 2. Describe range, cooktop, laundry, and bath venting stating the size and measure in linear feet. 3. Describe transitions and measure in linear feet stating the size at each end. 4. Describe elbows stating the size and enumerate. 5. Describe Y fittings stating the size and enumerate. 6. Describe fittings, hangers, and sleeve frames stating the size and enumerate these items. Mechanical Equipment 7. Describe and enumerate mechanical equipment items, including: a. Air handling units b. Furnaces

4 146 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK c. Heat exchangers d. Heat pumps e. Refrigeration compressors f. Refrigerant condensing units g. Water coolers h. Humidity control equipment i. Floor-heating and snow-melting equipment HVAC Controls 8. Describe control wiring and measure in linear feet. 9. Describe low-voltage wiring and measure in linear feet. 10. Describe and enumerate electric and electronic controls. 11. Measure both testing and balancing as items. Miscellaneous HVAC Items 12. Describe and enumerate permits for the 13. Describe duct insulation and measure in square feet. 14. Describe and enumerate fire stops and flashings. 15. Describe and enumerate cutting, drilling, and patching required for this 16. Measure cleanup resulting from this work as an item. Electrical Work Generally Residential plans generally show the location of light fixtures, switches, and at least some of the wiring. The location of duplex receptacles is also noted on the drawings, however, the layout of power wiring is seldom shown. Sketches, especially with colored pens, can here again be a great help to the estimator measuring the work of this trade. Measuring Notes Electrical Work Wiring 1. Describe wire, cable, and conduits and measure in linear feet. 2. Describe cable tray and bus duct systems and measure in linear feet. 3. Describe and enumerate hangers, sleeves, and supports. Electrical Equipment, Fittings, and Fixtures 4. Describe and enumerate electrical equipment, fittings, and fixtures, including: a. Fire alarm systems b. Security systems c. Communication systems d. Medium-voltage switching equipment e. Low-voltage switching equipment f. Electrical panels and sub-panels g. Junction boxes h. Outlet receptacles i. Switches j. Light fixtures k. Door bells l. Fans

5 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK 147 m. Range hoods n. Smoke detectors 5. Describe and enumerate installing appliances, including: a. Cooktops b. Microwave ovens c. Built-in ovens d. Range hoods Miscellaneous Electrical Items 6. Describe and enumerate permits for the 7. Describe and enumerate fire stops and flashings. 8. Describe and enumerate cutting, drilling, and patching required for electrical 9. Measure testing and hot checking entire system as an item. 10. Measure cleanup required as a result of this work as an item. Pricing the Work Estimating Shortcuts Materials can be priced in the usual manner using supplier quotes for the items involved. However, because the builder does not perform this work with their own forces, there will be no in-house historic cost information available to use to estimate the cost of labor and equipment for this The builder s estimator will, therefore, have to rely on productivities and prices obtained from subtrades if they are willing to share this information. Otherwise, the estimator will have to resort to publications such as RSMeans Plumbing Cost Data, 1 RSMeans Electrical Cost Data, and so on for prices. Instead of compiling a full takeoff on the smaller projects, many plumbing, HVAC, and electrical estimators use shortcuts to compute their prices for this Building estimators who need quick budget prices for these trades can also make use of these time-saving methods. For the plumbing, HVAC, and electrical trades, a price per square foot of gross floor area could be used to provide at least a rough estimate of the cost of that trade. Often, though, especially for bid estimates, something that gives a more accurate price is called for. Cost Per Fixture Plumbing Estimate A quick estimate for plumbing work can be obtained by means of a unit price for each plumbing fixture on the project. The cost of all necessary piping and any other required work is allowed for in each of these unit prices. So, enumerating the following fixtures and multiplying by the applicable price for each fixture will give the estimated price for the complete plumbing work: a. Floor drains b. Water heaters c. Lavatory basins d. Water closets 1. R. S. Means Company Inc., Kingston, MA

6 148 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK e. Sinks f. Laundry tubs g. Bath tubs Additional prices may be required for installing appliances, special fixtures, and any out-of-the-ordinary plumbing work requirements. Plumbing Example Suppose you are considering adding a three-fixture bathroom to a home design and you would like to know roughly what the plumbing price would be. The plumber can quickly estimate the price based on the number and type of fittings involved and all-inclusive price for these fittings. EXAMPLE 7.1 Estimate of plumbing price for a 3-fi xture bathroom: 1 bathtub 72" 3 36" $2,500 1 water closet $1,485 1 lavatory basin 19" 3 16" $1,160 $5,145 Extra for pipe and fittings 30% $1,544 Total $6,689 Quick Estimates of HVAC Work The cost of HVAC work can be estimated quite quickly by using a combination of prices per unit area and unit prices for items of equipment. The overall cost of ductwork including ducts and all fittings is proportional to the floor area of the house. A fairly accurate price per square foot, therefore, can be obtained from the analysis of projects that have been completed in the past. Thus, to estimate the total cost of ductwork for a house, multiply the unit price from a past project by the gross floor area of the new house. The estimator can also compile all-inclusive equipment item prices for each item of equipment used in the HVAC system. An item price would include the cost of purchasing the item of equipment, installing the item, and any further costs necessary to complete its installation. So, to compile a full HVAC estimate, determine how many of the following equipment items are required, and multiply by the appropriate item price for each: a. Furnaces b. Heat exchangers c. Refrigeration compressors d. Refrigerant condensing units e. Water coolers f. Humidifiers g. Kitchen and bathroom vents HVAC Example To quickly calculate the heating and ventilating price for a house, we can use a price per unit area and add the cost of non-standard fixtures. So, if the proposed house is

7 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK 149 2,200 square feet of floor area and a special humidifier and exhaust fan are required, this would be the estimate: EXAMPLE 7.2 Quick heating and ventilating price: Basic HVAC 2,200 SF at $5.50/SF $12,100 Humidifi er $2,500 Exhaust fan $350 $14,950 Quick Estimates of Electrical Work The cost of 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: 1. To estimate the full price of wiring for lighting, multiply gross floor area by the inclusive unit price per square foot. 2. To estimate the full price of power wiring and fittings, multiply the number of power outlets by inclusive price per outlet. 3. To estimate the price of equipment and fixtures, multiply the number of each item by unit price for that item, including: a. Electrical panels b. Subpanels c. Light fixtures d. Doorbells e. Fans f. Range hoods g. Smoke detectors h. Cooktops i. Microwave ovens j. Built-in ovens k. Range hoods Electrical Example To quickly calculate the electrical price for a house, we can use a price per unit area and add the cost of non-standard fixtures. So, if the proposed house is 2,200 square feet of floor area and a security system with motion detectors is required, this would be the estimate: EXAMPLE 7.3 Quick electrical price: Basic electrical 2,200 SF at $8.50/SF $18,700 Security system $3,500 $22,200

8 150 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK SUMMARY It is customary to perform plumbing, HVAC, and electrical work by subcontractors on residential projects. Because plumbing, HVAC, and electrical work accounts for so much of the total price of a project, it is useful for the building estimator to be able to check the subtrade quotes for these trades. Because building estimators sometimes estimate these trades on small projects, the ability to compile takeoff of this work can be useful to them. Very little information about plumbing, HVAC, and electrical work is found on drawings for small residential projects, so estimators often need to prepare sketches of this Plumbing pipes and gas lines are measured in linear feet in a takeoff. Plumbing fittings and equipment are enumerated. HVAC ductwork is measured in linear feet for each size of duct. HVAC fittings and items of equipment are enumerated. Electrical wiring, cables, and conduit are measured in linear feet. Electrical equipment, fittings, and fixtures are enumerated. Installation of appliances is enumerated. The builder s estimator will generally have to rely on publications such as Means Plumbing Cost Data in order to price plumbing, HVAC, and electrical Costs of plumbing, HVAC, and electrical work can be quickly estimated using the price per unit area estimating method. A quick estimate of plumbing work can be assembled using the cost per plumbing fixture method. A combination of price per unit area and unit prices per item of equipment can be used to generate a quick HVAC cost estimate. A combination of price per unit area and unit prices per item of equipment can also be used to generate a quick electrical work estimate. RECOMMENDED RESOURCES Information R.S. Means publishes specialized estimating texts for plumbing, HVAC, and electrical Information on the latest estimating software can be obtained with keywords: Plumbing, HVAC, and Electrical Estimating on your web search engine. Web Page Address REVIEW QUESTIONS 1. What portion of the total cost of a residential project does plumbing, HVAC, and electrical work together account for? 2. Why it is useful for a building estimator to be able to prepare a takeoff of HVAC work? 3. How much information about the plumbing system is usually provided on housing plans?

9 CHAPTER 7 ESTIMATING PLUMBING, HVAC, AND ELECTRICAL WORK To what distance outside the house are sanitary sewer lines measured in a plumbing takeoff? 5. How is piping insulation measured? 6. Describe how you would measure bathroom venting in an HVAC takeoff. 7. How is testing and balancing of an HVAC system measured? 8. If a cooktop is required for a kitchen, its cost is included in the builder s work, so why is it measured again as part of the electrical scope of work? 9. Wiring or conduit passing through walls sometimes requires fire stops or flashings. How are these items measured? 10. Describe a quick method for estimating the cost of HVAC PRACTICE PROBLEMS 1. Calculate a quick plumbing price for a four-fixture bathroom based on the following data: Fixtures: 1 bathtub at $2,450; 1 shower unit at $1,000; 1 WC at $1,400; and 1 Lavatory basin at $850. Also include an additional 30 percent for pipe and fittings. 2. Calculate quick plumbing, HVAC, and electrical prices for a 3,100-square-foot home based on the following data: Plumbing is expected to be $6.50 per square foot; HVAC $4.25 per square foot; and electrical work $6.75 per square foot.

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