Spike's Calculators

Roofing Calculator

Gambrel Roof - Asphalt Shingles

Spike's Calculators

Calculate the amount of asphalt/fibreglass shingles needed to cover a Gambrel roof.

Please remember the following information for calculating the amount of asphalt or fibreglass shingles required to cover a Gambrel roof. One pack of standard shingles can cover an area of 33 square feet. However, various types of shingles are available that are different in terms of the number of pieces they contain, the length of the individual shingle, and the square foot coverage per pack. Not all types of shingles can also be used for the starter strip and ridge capping. You could use ridge caps to cover the top ridge and the hips. That is why our calculator requires you to input the "square foot coverage of one bundle." The required shingle starter strip is given in lineal feet, which includes a row of shingles along the rakes. The number of shingles needed for starter strips is separate from the total packs you require and not included in the total.

Gambrel style roof

As a note:

One pack of standard shingles = covers 33 sq. ft. a pack.
But with all the different types available, not all packs are equal in the amount of pieces they contain, the length of the individual shingle and the square foot coverage per pack. Not all types of shingles can be used for the starter strip and the ridge capping needed or you could be using ridge caps to cover the top ridge and the hips. That is why this calculator requires "the square foot one pack will cover" and the results for starter strip and ridge capping is in lineal feet needed for those two items and is not included in the Total Packs Needed.

Shingles Calculator

Building Length ft inch
Building Width ft inch
Eaves Overhang inch
Gable Overhang inch
Wall to Upper Pitch Start ft inch
Upper Roof Pitch /12
Lower Roof Pitch /12
Coverage of One Pack ft²
Waste %

Results:

Roof Area ft²
Ridge Length lineal ft
Shingle Starter Strip lineal ft
Shingles Needed to Cover Roof packs
Waste Factor Adds: packs
Total Shingles Needed packs

Calculator

  1. enter the length of the building in feet
  2. the width of the building in feet
  3. the overhang of the eaves in inches
  4. the overhang at the gable in inches
  5. enter the wall to the upper pitch start. The length measured from outside the wall to where the upper slope from the Gambrel roof starts
  6. enter the pitch of the upper roof
  7. the pitch of the lower roof
  8. the coverage of one bundle of shingles in square feet
  9. a waste factor percentage

Results

  1. the area of the roof in square feet
  2. the length of the ridge in lineal feet
  3. the starter strip needed in lineal feet
  4. the number of bundles needed to cover the roof
  5. the amount your waste percentage adds
  6. the total number of packs needed for your roof, including what is calculated for waste
Gambrel Roof - Asphalt Shingles Calculator


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