Design Stage 1 Preconstruction Stage 2: Procurement Conceptual Planning Stage3: Construction Stage 4: Project Close-out Square Foot Estimating

S.F. Estimating Similar to the ROM estimating method Based on knowing the area and few more details Conducted during the conceptual phase for budgeting purposes Means publishes two guides: Assemblies cost data book (Fig 5-7) and Square Foot Data book (Figures 5-8 and 5-9)

Using the Reported SF Data Estimates are obtained using the Assemblies Cost Data Book, same as ROM estimating. Prices are based on 11,500 projects and are organized according to the quality (1/4, 1/2, or 3/4) Estimates are computed by multiplying the floor area times the price per SF. Adjustments are then made to the price as the ROM estimate. The price includes O&P but not design fees. Adjust for location, time, and design fees. Advantages: represent actual project data (true costs) Disadvantages: difficult to know exactly what is included in the price and it does not reflect the effect of different project situations

Example The cost of a 15,000 ft 2 library In Panama City, FL to start in June 2009 assuming median quality is: –15,000 X 161$/ft 2 from figure 5-7 = $2,415,000

Size factor (Figure 5-3) = 15,000/12,000 = 1.25 Cost multiplier (Figure 5-3) = 0.98 Cost adjusted for the size = $1,558,200 Location: Panama City Index = 70.6 Panama City Cost = X 1,558,200 = $1,100,089

–Time: Assuming 5.1% annual increase (as assumed under the historical cost indexes table in R.S Means Guide, the estimate was done assuming start of January For 1/2 year, the projected increase in price is 1.025% project cost in Panama City June 2009 = 1.025X1,100,089 = $1,127,591 (Fig 5.4)

Design fee from figure 5-10, design fee is about 7.27% Overhead and profit: Included Cost in Panama City June 03 including design fees = X 1,114,390 = $1,195,544 (( )/( ))*( ) -7.3= 7.27

Using the Modeled SF Data A more detailed method, requires more information than the area, the estimate is better fine-tuned Different projects of different sizes are tabulated, the cost of material, labor and equipment is estimated per unit. Knowing the size of the structure, the SF cost is also given. Two tables are given for each structure: –a table similar to ( Figure 5-8 )that gives the cost of the building according to SF, perimeter, type of exterior wall, story height, and area of basement. With the table, prices for common additives are given. O&P,design fees and size are included.

–A table similar to (Figure 5-9)that gives the unit and the SF price. The building is divided into 12 systems and 38 components The SF column is used to compute the cost used in the previous table at the specified size and to compare the components The unit cost column is used to obtain a more accurate estimate when a more detailed quantity take off is available. Distinguish between SF of floor area, S.F.. ground, S.F. roof, and S.F. slab. If the unit is “each” the number of units is = cost per S.F. X floor area / cost per unit Check the number of elevators in Figure 5-9, and item 4.6: how many elevators and doors?

Examples Assuming that only the area, perimeter, story height, basement area, type of exterior walls are known, use the first table. You must be able to compute areas and perimeters as fast and accurate as possible. What is the cost to construct a 15,000 ft 2 library in Panama City, FL assuming face brick with concrete block back-up, RC frame? The perimeter is 486 LF and 14’ story height. The building includes 5 Nickel cadmium emergency lights, 20 study carrels, 1 40’ Aluminum flagpole, 300 LF of double face bookshelves, 10 LF charging desk, and 10 laminated reading tables.

Answer Interpolating between (13,000 ft 2 cost $157.95), and (16,000 SF cost $154.05) in Figure 5-8, the cost at 15,000SF = (( )/( ))*( )= $ / ft 2.

Adjustments: –Perimeter = 486 LF: there is about 100 LF more than the typical model. From Figure 5-8, Add $10 Basic S.F. cost = $ $10.00 = $ $/ ft2 Building basic cost = $ X 15,000 = $ 2,480,250

–Additives: –From Figure 5-8: compute the cost of each additive and add it to the basic cost –How about the rest of the adjustments?

Area and Perimeter Computations Break down the area to smaller units. Write down all the computations Use the “recess method” to compute the perimeter. You will be asked in the exam to compute perimeters using this method. If the perimeter is known, the length of a parallel perimeter at a perpendicular horizontal distance HD = Per.  8 HD Examples on perimeter computations, handout

Review of the Adjustments Depending on the type of the estimate, size, design fees, or O&P may and may not be included. Size: –use table 5-2 or 5-3 to get the typical size –compute the size factor = proposed area / typical area –use the graph in Figure 5-3 to determine the cost multiplier based on the size factor cost adjusted for size = base cost X cost multiplier Location: –get the city index from a table similar to Figure 5-4 cost adjusted for location = cost adjusted for size X city index 100

Time: –cost at a time after the year in which the book was written: assume 5.1% annual increase. Fraction of a year is considered. –cost at a time prior to the year in which the book was written: use historical cost indexes cost in a previous year = current 30 city average cost X index at the city in the past or cost in a previous year = current city cost X index at the city in the past current 30 city average index A current index at the city B

cost in a previous year at a city/ index at the city in the past = current 30 city average cost /current 30 city average index = current city cost / current index at the city Or: Cost any location at a certain time index at that location and time = constant

using formula A, there is no need to adjust for location first. Depreciation: today’s value of a building n years old = today’s construction cost X (1-depreciation factor%) –consider the total apparent age of the building not the actual age –to estimate the value of a building built in year a and destroyed in year b, 1942 and 1973 for example, compute today’s value and adjust for depreciation for a-b years. When using the detailed tables: the number of units = cost per S.F. X typical area on top of the table / unit cost

A More detailed Example # 1 Salem, OR in 73,AR

(Included)

–A table (Figure 5-9)that gives the unit and the SF price. The building is divided into 12 systems and 38 components The SF column is used to compute the cost used in the previous table at the specified size and to compare the components The unit cost column is used to obtain a more accurate estimate when a more detailed quantity take off is available. Distinguish between SF of floor area, S.F.. ground, S.F. roof, and S.F. slab. If the unit is “each” the number of units is = cost per S.F. X floor area / cost per unit Check the number of elevators in Figure 5-9, and item 4.6: how many elevators and doors?

Estimating Using Detailed Tables Example (2) Using the unit cost information in the attached tables from of R. S. Means Square Foot Costs, compute the cost of building a 4 story parking garage in Salem, OR in Jan If: –floor area = 120,000, perimeter = 723 ft –ground area = 1.05 slab area –7” RC slab on grade with vapor barrier and granular base –story height = 11 ft –exterior walls are face brick with concrete block back up –three hydraulic passenger elevators. Assume that the cost of a single elevator is the same for 4 or 5 story building.