What Materials Do I Need for a 25-Square Roof?

Roofing Underlayment

• A properly installed roof requires a sound system of waterproofing under the finished roofing materials. Rolls of 30-pound roofing felt provide an excellent waterproofing membrane. A roll of 30-pound felt will cover approximately 200 square feet. Since a square of roofing is 100 square feet, a roof of 25 squares will require 12.5 rolls of 30-pound felt. (25 x 100 = 2,500 SF; 2,500 divided by 200 = 12.5 rolls.)

Roofing Material Selection

• Your choice of the finished roofing materials is optional. Weather extremes in your area figure strongly in your selection of materials. Consider the materials used in your prior roof as an option. Observe roofs in your area to see what type of roofing is common. Talk to local suppliers of roofing materials in your area for their recommendations on the best materials to use.

Material Requirements

• Typical roll roofing for low slope roofs is available in rolls that will cover 100 SF. A 2,500 SF roofing job will require more than 25 rolls of material. Allowance must be calculated for overlapping roofing courses and other waste. Composition shingles are usually packaged in bundles. Lightweight shingles require 3 bundles to a square. A 25 square roof will require more than 75 bundles of shingles when accounting for waste and trim. Heavier three-tabbed shingles and laminated shingles require 4 or 5 bundles to a square. Heavy shingles will require 100 to 125 bundles plus and allowance for waste and trim.

Roofing Attachment

• Roofing nails with large heads are used to apply roofing materials. Lightweight shingles use 1-inch nails and require 1.33 pounds per square of roofing. Apply 4 nails per shingle. Heavy three-tabbed shingles call for 1.63 pounds of 1-1/4 inch nails per roofing square. Apply 4 nails per shingle. Add 5 percent to the nail requirement for waste and loss. A 25 square roof requires 1.40 x 25 = 35 pounds of 1-inch roofing nails for light weight shingles. Heavier shingles required 1.70 x 25 = 43 pounds of 1-1/4 inch nails.