How to Estimate the Home Building Cost Per Square Foot

by Lee Grayson, Demand Media Google
    Accurately estimating home-construction costs requires using the blueprints for your new home.

    Accurately estimating home-construction costs requires using the blueprints for your new home.

    Estimating the cost of building a new home helps plan for the features you want, while staying within your basic budget. American home-building calculations exclude the property price, planters, driveway, sidewalks and landscaping around the property. The estimate also excludes pre-construction work such as lot grading and connecting utilities. Building costs vary with the individual contractor mark-up, geographic location and area labor costs. Costs also fluctuate with material shortages, such as wood for framing trusses. The features you select determine your final building costs, but looking at the basic blueprint details offers a general per-square-foot estimate.

    Items you will need

    • Home blueprints
    • Building materials list

    Step 1

    Calculate the total square footage of living space using your building blueprints. Add the square feet for all interior rooms under the main roof. Include the attic or porches only when used as four-season rooms. Do not include the footage for the garage area or patios.

    Step 2

    Determine the finishing class and construction quality for your new home. The highest-quality construction uses exterior masonry, shake, tile or architectural-grade shingles, reinforced concrete foundation with a basement or crawl space, and irregular walls and decorative openings. The mid-range class has a concrete or block foundation, some wall-height changes and architectural asphalt shingle roofing. Standard construction features basic asphalt roof shingles, concrete slab and square interior and exterior walls.

    Step 3

    Determine the grade for your bathroom finishing and construction materials using your materials list. High-quality construction has a minimum of four plumbing fixtures in each bath, electricity for eight or more built-in appliances and wiring for more than 80 light fixtures in the home. Mid-grade construction features three plumbing fixtures per bath, six built-in appliances and recessed lighting. Standard building quality allows for three basic plumbing fixtures, three built-in appliances and 10 or fewer standard light fixtures.

    Step 4

    Calculate the quality of your windows and doors from your materials list. The highest-class construction has large multi-pane glass windows, skylights or decorative windows and four or more exterior doors. Mid-grade construction features a decorative front door, quality exterior doors and at least one large window with multi-pane glass. Standard construction has hardboard doors and vinyl windows.

    Step 5

    Review the basic features of the home to determine the construction class. Homes with specialized heating and cooling features, such as solar or geothermal systems, and masonry fireplaces qualify as higher-quality construction. Mid-grade construction has one prefabricated fireplace and a high-efficiency heating and cooling system. Standard grade includes only a basic heating system.

    Step 6

    Determine the features of your kitchen from your building materials list. The highest-class construction uses custom cabinets, high-end appliances featuring built-in ovens, and finishes using granite or tiles. Mid-grade construction has high-grade commercial cabinets, quality laminate counters and a freestanding stove. Standard-grade kitchens have contractor-grade cabinets and lower-quality laminate, with the homeowner supplying the appliances.

    Step 7

    Review the rankings of high, mid or standard construction from the categories in steps 2 through 6, and multiply the total square footage by the construction quality that you've selected for the majority of the categories. For example, homes built with the majority of the features listed under the highest class of construction in 2012 used $110 as the multiplying factor. Mid-grade construction used the average square-foot cost of $95. Houses with standard features used $79 as a multiplier. Multiply the cost by the number of square feet from your blueprint calculations to estimate your building costs.

    Step 8

    Test your cost estimate by using neighboring new construction. Subtract the average cost of the land from the price of the comparison home, typically approximately 20 percent, and then divide the price of the new home by the square footage. Compare your calculations with the new, similar neighborhood construction to give you an average building cost-per-square-foot figure.

    About the Author

    Lee Grayson has worked as a freelance writer since 2000. Her articles have appeared in publications for Oxford and Harvard University presses and research publishers, including Facts On File and ABC-CLIO. Grayson holds certificates from the University of California campuses at Irvine and San Diego.

    Photo Credits

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