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 ft2 library In Panama City, FL to

start in June 2009 assuming median quality is:– 15,000 X 161$/ft2 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 = $1,558,200Location:

Panama City Index = 70.6Panama City Cost = 0.706 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 2009. 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 feefrom figure 5-10, design fee is about 7.27%

Overhead and profit:Included

Cost in Panama City June 03 including design fees = 1.0727 X 1,114,390 = $1,195,544

((7.3-6.4)/(5000000-1000000))*(1114390-1000000) -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 ft2 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 ft2 cost $157.95), and

(16,000 SF cost $154.05) in Figure 5-8, • the cost at 15,000SF =((157.95-154.05)/(16000-13000))*(16000-15000)= $ 155.35 / ft2.

• Adjustments:– Perimeter = 486 LF: there is about 100 LF more than the

typical model. From Figure 5-8,

Add $10Basic S.F. cost = $155.35 + $10.00 = $ 165.35 $/ ft2Building basic cost = $165.35 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 index100

• 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 indexA

current index at the cityB

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

Example 1Part 1

Decorative concrete block, steel frame, 4000 sf basement under materials labArea = 19,700 sfPerimeter = 1120 ft

Standard cost = 116.75 per sfPerimeter adj. = (520*3.25/100)= 16.9 per sfWall height adj. = (12-12)*0.75 = 0 per sf

standard hgt is 12', see top of table on the opposite pageAdjusted cost = 133.65

Above ground cost = (133.65*19700)= 2632905 $Basement cost = (17.15+133.65)*(4000)= 603200 $Total building cost = 3236105Commercial Texarkana location factor 0.761 $Cost at Texarkana, 2009 (0.761*3236105)= 2462675.91 $

_________________________________________________________________________________________________

Part 2Decorative block, steel frame 116.75 $per sfStucco on brick, bearing wall 113.2 $per sfSavings= 3.55 $per sf

Height difference = 4 ftSavings per foot = 0.75 $per sfSavings = 3 $per sf

Total savings per sf= 6.55 $per sfTotal area = 19700 sfTotal savings = 129035 $Location factor = 0.761Savings at Texarkana = 98195.635Percent savings = (98,195/2,462,676) 3.99%

________________________________________________________________________________________________

Part 3Design fee = 9.7%*2588884 238879.563(Included)

Part 4 cost index 1973, see historical cost index 20.330 city average cost 2009 323610530 city average cost in 1973= 0.203*3236105 656929Cost at Salem, OR 1973 (Location factor 100.2) 658243

Part 4 cost index 1973, see historical cost index 20.330 city average cost 2009 323610530 city average cost in 1973= 0.203*3236105 656929Cost at Salem, OR 1973 (Location factor 100.2) 658243

Part 5Age depreciation 2009-1973+10 = 46 yearsLocation factor Salem 1.00230 city average cost 2009 32361052009 Replacement cost in Salem= 1.002*3236105 3242577.21Less depreciation at( 1-0.46) (from depreciation table) 1750991.69Today's value 1491585.52

What is the use of this value?

– 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 TablesExample (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 2009. 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.

AnswerData Preparation:Ground area = 1.05 *(120,000/ 4) = 31500 S.F.

Area of exterior walls: It is not clear how many levels of exterior walls are there. To figure that out:area of walls per floor = 0.4 *10' * 723 = 2892 ftcost of exterior walls per floor = 2892 S.F. * $17.95= 51911.4 $total cost of exterior walls, 5 story building = $1.79* 145,000 259550 $number of wall levels In a 5 story building = 259550/51911.4= 4.999865there are 5 levels of walls In a 5 story building, there are 4 levels of walls in our 4 story building

Area of exterior walls = 4* (0.4*11)*723 12724.8 S.Fcheck: the cost for 5 floors, 10' height = 12724.8*17.95*5/4*10/11= 259557 $

Area of elevator shaft walls = (4/5)*{(0.47*145000)/9.07}*3/2) 9016.538 S.F.

Area of elevated floors (3 floors) 3* (120000/4)= 90000 S.F.Number of plumbing fixtures = 120,000 / 18,125= 6.62069

say 7

CostUNIT Quanitity unit cost cost $

1.0 Foundations0.1 Footings & Foundations S.F. ground 31,500 7.65 2409750.9 Excavation & backfill S.F. ground 31,500 0.86 27090

2.0 Substructure0.1 Slab on Grade, 7" RC. See Means page 232S.F. slab 30000 3.68 110400

page A-113.0 Superstructure

0.1 Columns and beams S.F. floor 120,000 4.3 5160000.4 Structural Walls, elevator shaft S.F. wall 9016.538 9.07 817800.5 Elevated Floors only elevated slabs S.F. floor 90000 7.22 6498000.9 Stairs Flight 2270 18160

4.0 Exterior Closures0.1 Walls S.F. wall 12724.8 17.95 228410.2

7.0 Conveying0.1 Elevators, three Each 3 102225 306675

8.0 Mechanical0.1 Plumbing, 1 fixture/18,125 S.F floor Each 7 13,231 926170.2 Fire Protection S.F. floor 120,000 0.04 4800

9.0 Electrical0.1 Service and Distribution S.F. floor 120,000 0.14 168000.2 Lighting and Power S.F. floor 120,000 1.7 2040000.4 Special Electrical S.F. floor 120,000 0.11 13200

11.0 Special Construction0.1 Specialties S.F. floor 120,000 0.59 70800

Sub-total 2581507General Conditions (O&P) = 15% 387226.1Architect Fees 6% 154890.4

Total building cost 3123624

cost per S.F. = 26.0302Cost at Salem, OR (location factor = 1.002) = 3,123,624 *1.002= 3129871