Building By The Square Foot


How much material is it going to take to do the job? What is the labor cost for the project? These are questions a contractor asks himself when bidding a job. In most cases a contractor will use the square foot method to determine the answer to those questions.

This method of take off is particularly handy in figuring sheet good type materials such as wall sheathing, plywood decking, roof sheathing and drywall. To find the square footage for one of these areas, multiply the height or width times(x) the length. For example if you have an eight foot high wall by 40 feet long the square footage for the wall would be 320 square feet. Most sheet goods are 4 feet by 8 feet or 32 square feet. The square footage of the wall is divided by 32. It will take 10 sheets of plywood or insulated sheathing to cover this wall.

This same method can be used to figure the plywood or OSB for the house deck and roof. To figure the deck simply multiply the width of the deck by the length to get the square footage and divide by 32. Figuring the square footage of a roof is similar but with a twist. For the roof multiply the length of the rafters by the length of the roof. Take the result times 2 for the total square footage for both sides of a gable roof, then divide by 32 to get the amount of plywood to sheet the roof. The square footage of a hip roof is figured the same way.

Drywall is also figured by the square foot. This can be an involved process. It can be broken down into two parts. First the square footage for the ceilings can be figured. Like the deck this is figured length times width. Then the lineal feet of all the walls is taken times the height. Interior walls will be added in twice because they have drywall on both sides. Labor to hang, tape, and paint the drywall is also figured this way.

Besides drywall and painting, many other labor costs are figured by the square foot. Roofing and siding are figured by the square. A square is 100 square feet. For example if a roof is 1200 square feet, it will take 12 squares of shingles to cover it. The same unit of measurement goes for vinyl, wood, alumimnum, steel and cement sidings.

Carpentry makes use of this measurement also. The cost to frame a house is usually figured by the square foot. Costs to build a whole house are estimated this way to help people determine if a house or its house plans are affordable for them to build.

Flooring is also among one of those things that use the square foot method to figure labor and materials. This includes ceramic and quarry tiles, hardwood, laminate, and vinyl flooring, and carpeting. Most contractors and installers use a price per square foot for their labor when calculating their costs for installation.

This information will help you understand contractor estimates and help you do your own calculations for projects.

Mike Merisko(c) 2007




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