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Chapter. 35. Estimating Building Costs. Objectives. Explain the process of estimating the building cost for a residence. Prepare a preliminary estimate of the cost of a residential structure using the square foot or cubic foot method. Generate a final estimate for a simple structure.
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Chapter 35 Estimating Building Costs
Objectives • Explain the process of estimating the building cost for a residence. • Prepare a preliminary estimate of the cost of a residential structure using the square foot or cubic foot method. • Generate a final estimate for a simple structure.
Introduction • Estimating is an organized effort to determine total cost of materials, labor, and other services required • Made after house has been designed, construction drawings completed, specifications prepared
Preliminary Estimates • Preliminary estimate created at design stage • Estimates probable costs and to place limits • Design contingency indicates how much cost overrun may occur on project • Two manual methods of estimating building costs are square foot method and cubic foot method
Square Foot Method • Estimate based on total area of house • Compute number of square feet in house • Multiply square footage by constant value, determined by local conditions • Garages, porches, basements figured separately, at about one half of living area cost • Square footage determined by multiplying house length by house width
Square Foot Method Example • 24' x 60' house, 20' x 20' garage • Living area 1440 square feet, garage 400 square feet • $100 per square foot building cost for living area • 1440 x $100 = $144,000 • $50 per square foot building cost for garage • 400 x $50 = $20,000 • Total cost: $144,000 + $20,000 = $164,000 • Price of land not included
Cubic Foot Method • Based on volume of house • Volume found by multiplying area by height • Height is distance from floor to ceiling for each level of house including basement • Attic volume included, calculated by multiplying area by 1/2 of rise
Cubic Foot Method Example • 24' x 60' house • Living area 1440 square feet, height 8' • 1440 x 8 = 11,520 cubic feet in living area • Attic area 1440 square feet, rise 4' • 1440 x 2 = 2880 cubic feet in attic • Total volume is 14,400 cubic feet • $10 per square foot building cost for living area • 14,400 x $10 = $144,000 • Total building cost for house, $144,000
Cubic Foot Method Example • 20' x 20' garage • Volume 400 x 8 = 3200 cubic feet • Garage attic rise, 3' feet, 400 x 1.5 = 600 cubic feet • Total garage volume, 3200 + 600 = 3800 cubic feet • $5 per square foot building cost • 3800 x $5 = $19,000 • Total estimated building cost, $144,000 + $19,000 = $163,000 • Price of land not included
Employability • Entrepreneurship • Entrepreneurs are people who start and run their own businesses • Work for themselves, feel a sense of accomplishment, can be financially rewarding • Entrepreneurs do their own work, plus all the work for the business (marketing, accounting) • Do your research before committing to entrepreneurship
Architecture Green • Costs of green building design • Initial building costs for green building are higher than costs for traditional construction • An experienced estimator can help a client build a sustainable home for little more than traditional building costs • Keeping up-to-date on available products, processes, and guidelines allows estimator to provide green solutions that may not increase cost of home
Final Estimates • Preliminary estimates can vary considerably from actual cost • More accurate cost estimate is final estimate, or material takeoff • Created by outside company specializing in estimation
Materials Estimate • Estimator compiles list of materials required • Once listed and priced, total material cost calculated
Labor Estimate • Can range from 60% to 89% of total building costs • Costs vary widely throughout United States • Use publications that provide detailed information regarding labor costs for various areas of country • General contractors and subcontractors can also provide help in projecting costs
Other Costs • Insurance • Fees for permits • Environmental impact fees • Other fees • Once evaluation of costs is complete, total building cost can be calculated • Variations from preliminary estimate may be due to materials price fluctuations, labor overruns
Computer Estimates • Software programs for estimating save time • Floor plan is imported, analyzed, and costs are automatically calculated
Computer Estimates • Estimate for electrical work required on a residential construction project.
Organizing Estimates • Organized according to work breakdown structure (WBS) • Common systems are MasterFormat and UniFormat • UniFormat system more commonly used for preliminary estimates • MasterFormat system used for final estimates
MasterFormat System • Numbered divisions and titles identify construction requirements, products, activities • Not all divisions apply to residential construction • Some divisions reserved for future use • Divisions are organized under groups and subgroups