35 Estimating Building Costs Chapter Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Objectives Explain the process

35Estimating Building

Costs

Chapter

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

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

• 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

Green


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

Documents

35 Estimating Building Costs Chapter Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Objectives Explain the process