Sunday, August 25, 2019

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Calculating Underlayment for Roofing

Based on the roof shown below, estimate the amount of 30-pound underlayment required. Assume single coverage, a crew-error waste of 4 percent, and a slope of 6 in 12.


  • Roof Plan area = (30’ x 60’) + (30’ x 15’) = 2,250 sf
  • Actual Roof area = Roof Plan Area times factor for 6 in 12 slope-roof

    Note: the factor comes from a table like the one shown below


    Actual Roof Area = 2,250 sf x 1.118 = 2,515.50 sf = 25.16 Roofing Squares

  • Total Ridge length, according to the plan is 40’ + 15’ = 55’
  • Total Hip and Valley. There are 6 hips and 2 valleys. To calculate their actual length multiply 15’ (their run) times 1.50 = 22.5

    Note: 1.50 is the update by which you multiply the run to get the actual area.


    22.5’ x 8 (the number of hips and valleys) is 180’

  • Total Hip – Ridge – Valley lineal feet is 55’ + 180’ = 235’
  • Total Hip – Ridge – Valley needs 1 square foot of material per lineal foot. Since it has 171 lineal feet, it needs 235 square feet or 2.35 roofing squares.
  • Total gross Roofing material = Area + Hip – Ridge – Valley = 25.16 squares + 2.35 squares
  • Account for waste factor of = 27.51 squares + 4% = 28.61 squares
  • Number of #15 underlayment Rolls needed.

Find a table which gives you the coverage for the different types of underlayment.


From the table, you can see that 1 roll of # 15 underlayment covers 4 squares, so

28.61 squares/2 squares per roll = 14.305 rolls is the answer.

Glossary for Business, Law & Procedures Exams for Contractor Licensing

An Account can be defined as a group of transactions that have something in common.
Account Payable
An Account payable is money owed by a company to its creditors or suppliers.
Account Receivable
An Accounts Receivable is money owed to a company by its debtors or customers.
Accrual Method of Accounting
In Accrual accounting, revenue is recorded when earned, and expenses are recorded when consumed, not when paid.
Accumulated Depreciation
Accumulated depreciation is the total amount of a fixed asset's cost that has been allocated to depreciation expense since the asset was put into service.
Adjusted Depreciation Base
Adjusted Depreciation Base is the current value minus the declining balance depreciation of last year.
An Asset is anything the business uses for its operations, regardless of whether it has been paid in full or not. If a company uses a pick-up truck which it still owes entirely to the bank, it is still considered an asset.
Bad Debts
A bad debt is a debt that cannot be recovered.
Billing Date
Billing date is the date when the invoice is officially generated.
Break-Even Point
The Break-Even Point is when a company's revenue equals its expenses, there is no profit and no loss.
A budget is an estimate of income and expenditures for a set period of time.
Cash Discount
A Cash Discount is a deduction allowed by the seller of goods or by the provider of services in order to motivate the customer to pay within a specified time.
Cash Method of Accounting
In Cash Accounting, revenue is recorded when cash is received from customers, and expenses are recorded when cash is paid to suppliers and employees.
Completed Contract Method
Completed Contract is an accounting method in which revenue and profit are recognized after the project has been completed.
Current Asset
A current asset is one which can be AND is expected to be converted into cash within 12 months during the regular course of business.
Current Liability
A Current Liability is an amount due to a creditor which must be paid within 12 months within the regular course of business.
Declining-Balance Depreciation
Declining-Balance Method is a depreciation technique where a constant percentage is applied to the book value of an asset.
Depreciation Base
Depreciable Base is used to describe the value that is divided by the service life of the asset to determine the annual depreciation expense under the straight-line method. The depreciable base is the value of the asset to be written off over time.
A Depreciation is the means through which a company writes off the loss it experiences through the wearing down of its assets. Methods of calculating depreciation include straight-line and declining-balance.
Financial Ratios
Financial Ratios are used to evaluate different aspects of the condition of a company. Some examples of typical ratios are working-capital ratio, quick-assets ratio, and debt-to-equity ratio.
Financial Statements
Financial Statements are written records that convey the financial activities and conditions of a business. Examples of Financial statements are the balance sheet, the profit and loss statement or income statement, and the statement cash flows.
Fixed Asset
A fixed asset is one that cannot and is not expected to be converted into cash within 12 months during the regular course of business.
Incentive Discounts
Incentive Discounts is a percentage that is discounted from an invoice when paid within a specific number of days.
Job Costs Accounting
Job costs accounting is the process of assigning the costs incurred on a specific job.
A liability is an obligation which a company has, which can be reported on its balance sheet. An example of a liability account is accounts payable.
Modified Accelerated Cost Recovery System (MACRS)
The modified accelerated cost recovery system (MACRS) is a depreciation system that allows the capitalized cost basis of assets to be recovered over a specified life of the asset by annual deductions for value depreciation.
Net Working Capital
Net Working Capital is the aggregate amount of all current assets and current liabilities. It is used to measure the short-term liquidity of a business.
Operating Cycle
An Operating Cycle is the average period of time required for a business to make an initial outlay of cash to produce goods, sell the goods, and receive cash from customers in exchange for the goods.
Overhead Expenses
Overhead expenses are those required to run a business, but which cannot be directly attributed to any specific business activity, product, or service.
Owner's Equity
Owner's Equity represents the owner's investment in the business minus withdrawal plus net income since the business began.
Percentage Method
Percentage Method this method works for any number of withholding allowances the employee claims and any amount of wages.
Percentage of Completion
Percentage of Completion is an accounting method that designates income and expenses for the portion of work which has been completed on a project.
Petty Cash
Petty Cash is an accessible store of money kept by an organization for expenditure on small items.
Salvage Value
Salvage Value is the estimated resale value of an asset at the end of its useful life. It is subtracted from the cost of a fixed asset to determine the amount of the asset cost that will be depreciated.
Source Documents
Source Documents are the original record containing the details to substantiate a transaction entered in an accounting system. Examples of Source Documents would be invoices and receipts.
Statement of Cash Flows
A Statement of Cash Flows usually shows how the net profits of business have been used, for example, distribution to owners, payment of liabilities, purchasing new assets.
Straight-Line Depreciation
Straight-Line Depreciation is the default method used to gradually reduce the carrying amount of a fixed asset over its useful life.
Useful Life
Useful life is the estimated lifespan of a depreciable fixed asset, during which it can be expected to contribute to company operations.
Wage Bracket Method
Wage bracket withholding tables are used to calculate the amount of income that the employer must withhold from each employee's paycheck.
Wage Range
Wage Range is the range of pay established by employers to pay to their employees who are performing a particular job or function.
Withholding Allowance
Withholding allowance refers to an exemption that reduces how much income tax an employer deducts from an employee's paycheck.

Calculating Withholding Allowances on a Contractor's Business Exam

There are several methods of evaluating income tax withholding, there are:

All these methods can be used just knowing the information on an employee’s W-4, the Wage Bracket and Percentage Methods are enough to answer any question about withholding allowances on a construction business exam.

Wage Bracket Method

  • Find the proper table on the back of the circular E. To pick the right table you need to know the marital status of the person (single or married), and the frequency of pay (weekly, biweekly, month, etc.)
  • Identify the number of withholding allowances explained by the employee in her W-4 form.
  • Identify the wage range that the employee falls under. For example, 500 to 510 dollars per week
  • Find the intersection between the row containing the wage range and the column containing the month of withholding allowance claimed.
  • The intersection found on step 4 contains your answer, the dollar amount which must be withheld from the paycheck.

If your problem has more than 10 withholding allowances, then you must follow these steps instead:


  • Subtract the result from the employee’s wages.
  • On this amount, find and withhold the tax in column 10 for allowances.

Example 1: Use the wage bracket method to determine the income tax withholding for Craig Smith. He is married, gets paid weekly and makes $900 per week. On his W-4 form. He claims 4 withholding allowances. Solve using the 2016 circular E (Note that on your test, the answer will be looked on the circular E you are using. Your business book has within it a circular E excerpt)


  • Identify the correct table (married, weekly)
  • Locate the number 4 on the top row, that’s the column you will be working with
  • Locate the wage range using the first two columns. Notice we must pick “900 910”. We cannot use “850 860”, this is the row you will be working with.
  • Locate the intersection of column “5” and row “850 860”
  • The intersection is “47”, $30 is the amount to be withheld our answer!

Example 2: Use the Wage Bracket Method to determine the income tax withholding for Karl Smith. He is married, gets paid weekly and makes $1500 a week. On his W-4 form he claims 11 withholding allowances.


  • The number of withholding allowances over 10 in 1 (11-1). One weekly allowance is $77.90, we find this by looking at the correct row within Table 5.
    2 times $77.90 = 155.80
  • Subtract $155.80 (the result of steps) from the employee wages, $1500. $1500 – 77.90 = 1,422.10
  • On the amount calculated in step 2, calculate the withholding based on 10 withholding allowances, this means we must fund the intersection between row “1240 1250” and column “10”. The answer is “54”.


Percentage Method

The percentage method works with any amount of wages and any number of withholding allowances. To use this method (dollar amount), follows these steps.


  • Subtract the amount from the employee wages
  • Determine the amount to withhold for the appropriate table.


Example 3: Jim Beam gets paid $900 weekly and is unmarried. She has claimed two withholding allowances. Use the percentage method to calculate the amount to be withheld. Note that for this solution we will use numbers from the 2016 Circular E.

  • From table 5, we know that one withholding allowance for weekly is $155.80. (Multiply $155.80 times 2 (2 is the number of withholding allowances claimed)
  • Subtract the answer of step 1 from the wage amount. 900 – 155.80 = 744.20
  • The appropriate table is “table 1 – weekly Payroll Period”. The left side of the table is for Singles and the correct row is $222 $767”, which says “$17.90 plus 15% of the excess over 222”

She makes $578 in excess of 222 (744.20 – 222 = 522.2)

17.90 plus 15% of 522.2

17.90 plus 78.33 = $96.23


Glossary for Roofing Contractor Exam

Butterfly Roof
Common Rafter
Common Rafter is a rafter that extends perpendicularly from the top of an outside wall to the ridge board.
Dutch Hip Roof
”Dutch Hip
Eave is the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building.
Exposure/Exposed Distance
Exposure/Exposed Distance is the height of a shingle which is exposed to the elements, that area which is not covered by another shingle course.
Factor is a number used to multiply an input in order to obtain an output. These numbers are normally calculated based on more complex formulas to ease the complexity of common calculations.
Factory Square
Factory square is one square of 108 square feet.
Gable and Dormer Roof
”Gable and Dormer
Gable and Valley Roof
”Gable and Valley
Gable End
Gable End is the generally triangular portion of a wall between the edges of intersecting roof pitches.
Heel-cut rafters
Heel-cut rafters is a notch cut at the end of a rafter to permit it to fit flat on a wall and on the top, doubled, exterior wall plate.
Hip and Valley Roof
”Hip and Valley
Hip Jack Rafter
Hip Jack Rafter is a rafter that extends from an outside wall to a hip rafter.
Hip Rafter
Hip Rafter is a rafter that extends diagonally from an outside corner of a building to the ridge board.
Isosceles Triangle
Isosceles Triangle is a triangle with (at least) two equal sides. In the figure above, the two equal sides have length and the remaining side has length.
Mansard Roof
Pitch is most often applied to the angle or slope of a roof and is defined as “rise over run”.
Ridge board
Ridge board is the board placed on the ridge of the roof onto which the upper ends of other rafters are fastened.
Ridge Rafter
Ridge Rafter is a common rafter that runs parallel to the ridge board.
Rise is the vertical change in height per unit of horizontal distance or run.
Roofing Square
Roofing square is 100 square foot of roof area or a 10 by 10 section of one roof.
Shingle Course
Shingle course is one row of shingles.
Shingles are a roof covering consisting of individual overlapping elements.
Slope is a surface of which one end or side is at a higher level than another; a rising or falling surface.
Span is a common roof having two slopes and one ridge with eaves on both sides.
Total Rise
Total Rise is the distance from the ground to the top of the finished floor.
Total Span
Total Span is an anthropometric determination of the distance between the tips of the middle fingers at maximum arm stretch without straining.
Underlayment is a water-resistant or waterproof barrier material that is installed directly onto your roof deck.
A valley is the intersection of two downward-sloping sections of roof (the opposite of a ridge).
Valley Jack Rafter
Valley Jack Rafter is a rafter that extends from the ridge board to a valley rafter.
Valley Rafter
Valley Rafter is a rafter that extends diagonally from an inside corner of a building to the ridge board.

Length-of-Ridge on Hip Roofs

For calculating the length of a ridge simply subtract the width from the length. For example, assume the roof shown below is traditionally formed.


Ridge = Length – Width = 60’ – 30’ = 30’

The simplicity of this formula might surprise you, but it is converted indeed. To prove it, let’s do the same calculation in a direct way.


100’ – 15’ – 15’ = 70’

The reason why the distance from the eave to the ridge is 15’ is that they form isosceles triangles which have two 45 degrees angles and a 90 degrees angle; the two 45 degree angles must have the same length or shown below: