Builder’s Math: Sessions 1 & 2

The required ventilation for a 3,000 square foot roof is 1/300 of the horizontal roof projection area. The ventilation will be evenly split between ridge vents and soffit vents. How many square feet of soffit vent are required to comply with the ventilation requirements?

You are in the process of determining the cost for your job. An area measuring 14′ x 16′ x 8′ high will need 3/4 inch plywood floor decking. An area measuring 18′ x 16′ x 8 ‘ high will need 1/2 inch plywood floor decking. The costs are $20 per sheet for 3/4″ plywood and $12 per sheet for 1/2 inch plywood. Calculate the total cost for all of the plywood floor decking?

A benchmark on a site plan has an elevation of 118.42 feet. Finish grade has an elevation of 115.22 feet. The finish grade is how many feet lower or higher than the benchmark?

The outside measurements of a 12-inch thick concrete foundation wall are 20 feet x 50 feet. The distance from the top of the foundation wall to the top of the footing is 4 feet. Both sides of the foundation wall will be formed using 4-foot by 8-foot plywood sheets. How many sheets of plywood will be needed to form the foundation wall?

If a gable roof has a span of 40 feet and the rafter slope is 3 in 12, what is the height of the ridge?

You are constructing a wall using 2 X 4 wood. If the wall will be 48-feet long, how many studs will be needed for spacing 16 inches on center?

Calculate how many cubic yards of concrete are needed for a basement floor 30′ x 42′ x 4 inches thick.

Calculate how many cubic yards of concrete are needed for a trench footing 24′ x 24′ x 4′ deep by 1′ wide.

Calculate how many cubic yards of concrete are needed for basement walls, without footing, 24′ x 40′ x 9′ high, 8″ thick.

Calculate how many cubic yards of concrete are needed for a driveway 80 feet long x 16 feet wide x 6 inches thick.

Calculate the number of 8 inch masonry blocks required to construct a foundation wall with a total perimeter of 144′ and 11 courses high.

Calculate the number of squares of shingles needed to cover a gable roof 40 ft. in length and 16 ft. wide on each side (disregard for caps and starter).

Calculate the square footage of the gable end of a roof for vinyl siding. Total length 36 ft. by 6 ft. at ridge.

Calculate the s.f. of drywall needed to finish a room 10′ x 12′ x 8′ high. Do not subtract for doors or windows.

Calculate the cubic yards excavated for a basement. Total rough opening 42′ x 38′ x 9′ deep.

Calculate the cubic yards excavated for a trench footing
60′ x 38′ x 4′ deep, 2′ wide.

10 pieces of 1″x12″x10′ long = _________ board feet.

2 pieces of 1 1/4″ x 10″ x 8′ long = _________ board feet.

24 pieces of 2″x 4″x 8′ long = _________ board feet.

Calculate the number of floor joists needed for a floor system 60′ X 30′ with a steel floor beam in the center. Use 16′ joists. Do not include partition supports, headers, etc.

Estimate the number of 4 X 8 sheets of flooring material needed for a 60′ X 30′ area with no floor openings.

A new construction home requires 20,000 square feet of common brick. How many bricks will be required?

A garage measuring 32 feet by 32 feet is to have a conventionally framed gable room with a 4/12 slope. There will also be a 2 foot overhang. What length of 2 x 8 pre-cut would you purchase that would not waste money, labor, or material? (No additional knee wall or purlin required).

Total “run” for a flight of steps is 12 feet. The “rise” is 8 feet. Which of the following 2 x 12 lengths is the most suitable?

What is the diagonal measurement of a 12 x 16 wood deck?

A gable truss spans 40 feet if the slope is 3/12. What is the rise height at the ridge?

Determine the cost per square foot to construct the following concrete forms.Labor Required = 11 HoursCost per Hour = $10.64Total Square Feet of Concrete Forms = 100 square feet.

You are responsible for the grading and excavation on the work site. Your level (transit) reads 6.4 ft on a leveling rod that has been set up on top of a benchmark that has a given elevation of 100.0 ft. The finish grade as shown on the blueprints is 96.80 ft. Calculate what the rod reading should be on the finished grade after all fill has been placed, compacted, and graded?

You are constructing a gable roof on a new residential home. The roof measures 44 feet long. The 16-foot roof rafters are spaced 24″ on center. What is the total number of 4 X 8 sheets of plywood are needed to deck the roof?

Calculate the vent area required for a crawl space of a 22′ X 60’ house. A vapor does not exist on the floor of the crawl space.

Calculate the solution to the following problem.Horizontal run = 85 feetChange in elevation per foot = -1/4″What is the change in elevation over 85 feet?

A homeowner has a contract with a builder for $2,200. The owner gives the builder a $225 deposit. After three months, the balance of the contract is due with a simple interest rate of 15%. What is the payment amount that the homeowner will give to the builder?

A nonexempt, hourly painter employed by your company earns $5.00 hour. The employee works 47 hours in a work week. According to the Minimum Wage Law of 1964, calculate the employees gross wage for the week?

Calculate the net worth of the contractor from the following information:Assets = $1,943,553Liabilities = $1,297,887

All of the builder’s suppliers offer terms of 2%/10, net 30, 1.5% per month penalty over 30. The builder has one statement in the amount of $15,000 dated January 1, one statement for $6,000 dated February 1, and one statement for $5,000 dated March 1. What is the total amount the builder must pay to settle these statements on March 5?

In reference to the Balance Sheet, what are the company’s total liabilities?

In reference to the Balance Sheet, what are the company’s total assets?

In reference to the Balance Sheet, what is the company’s total net worth?

An hourly employee receives $18.00/hr. His workers comp insurance is 20%, social security is 6.2%, Medicare is 1.8%, and liability insurance is $0.25/hr. The employee’s hourly cost is:

John Doe earned $560.00 on his last paycheck. At 6.2% for social security, what was the deduction for social security tax?

According to fair labor practices, if John Doe is paid $18.00/hr and he worked 51 hours, his total earning are

You are bidding on a job with a total direct cost of $48,000. The overhead for your company is 10% of direct costs. What would you need to bid in order to make a profit of $7,100?

Calculate how much tax should be refunded or paid based on the following information:Federal Income tax you have paid for the year= $4,754Federal Income tax owed for the year = $5,797

Financing for a new home requires a 20% down payment. What would be the amount financed if the cost of the home is $164,062?

You are bidding on a kitchen renovation for a customer. You estimate the following costs:Materials = $2,500 Labor = $1,400You will need to add 12% of direct costs to cover your overhead and 5% of total cost to make the profit margin you desire. What will be your estimate for the job?