How to use a Roofing Material Calculator


A roofing material calculator is a very helpful tool.  When calculating the price of materials for your new roof, a roofing material calculator allows you to do this quickly.  It enables you to estimate the size of your roof and the required roofing materials and the cost.  To do a calculation, simply enter your roofing dimensions, choose roof type and pitch and it will give you the cost for 30-year asphalt roofing shingles.

Measure your roof from the ground up, adding any overhangs to the total roof size.  Estimate the roof pitch (slope) and enter the dimensions and pitch into the calculator.  State whether it is a Gable roof, Hip roof or Mansard roof.  Only rectangular roofs can be used in these calculators, without valleys or dormers.

There are many roofs with irregular shapes, and it is not possible to account for them within the scope of these calculators.  If your roof has an irregular shape or is rather cut up, try using the factor multiplier (roof difficulty setting in the calculator) for a more accurate estimation.

Roofing Material Calculator: How Roofing Materials Prices are Calculated:

The results of the calculation of roofing materials, include the roof size in square feet as well as a detailed list of the required materials need for a new roof installation.  It will include the following:

  • Roofing Shingles – price per square (100 sq. Ft.)  – three bundles of shingle in one square
  • Roofing Underlayment – 30 lb Felt, Ice and Water Shield along the roof eaves
  • Drip Edge
  • Miscellaneous accessories – nails, pipe boots,
  • Step flashing (for chimney flashing),
  • Roofing caulking
  • Ridge Vent
  • Ridge cap shingles
  • 3-tab shingles for starter course

All roofing prices are based on what national building materials retailers such as Home Depot and Lowe’s charge for roofing materials.  Prices are virtually the same here as trade prices where most contractors buy their materials.  In fact, Home Depot’s price on GAF Timberline architectural shingle is actually lower than most trade roof supply places.

The following types of shingles – Three tab asphalt shingles (25 year), 30 year common architectural shingles and 50 year asphalt shingles will all have prices provided.

There are four major asphalt roofing shingle manufacturers in the USA/Canada, and the prices are averaged among them.  There is also a waste factor to be taken into account for each type of roof:  Gable, Hip and Mansard’s roof waste factors are 7.5 per cent.  Mansard roofs have a flat roof in the center and often windows along the Mansard side, so adjustments need to be made to the waste factor at some point, as well as add an option in the calculator to select the number of Mansard roof windows.



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