Roofing Estimating Guide
Roof installation, replacement, and repair estimating for residential and commercial projects.
Overview
Roofing is estimated by the square (100 square feet). A thorough estimate accounts for tear-off and disposal, underlayment, flashing, ventilation, and the roofing material itself. Steep slopes, multiple layers of existing roofing, and complex roof geometry with many valleys and penetrations all increase labor costs significantly.
Common Projects
- →Asphalt shingle tear-off and replacement
- →Metal roof installation
- →Flat roof (TPO, EPDM, or modified bitumen)
- →Storm damage repair and insurance restoration
- →Gutter and fascia replacement
Pricing Factors
- ✓Roof area measured in squares (100 sq ft)
- ✓Number of existing layers to tear off
- ✓Roof pitch and accessibility
- ✓Number of penetrations, valleys, and hips
- ✓Material type (architectural shingle, metal, flat membrane)
- ✓Disposal and dumpster costs
Materials List
- •Shingles, metal panels, or membrane roofing
- •Synthetic or felt underlayment
- •Ice and water shield membrane
- •Drip edge and rake flashing
- •Step and counter flashing
- •Ridge cap and ridge vent
- •Roofing nails and fasteners
- •Pipe boots and vent flashing
Estimating Tips
- ★Always measure from the roof, not from the blueprint — actual dimensions account for overhangs and waste.
- ★Add a waste factor of 10-15% for standard roofs and 15-20% for complex cut-up roofs.
- ★Include dumpster rental and disposal fees in every tear-off bid — they can run $400-$800 per dumpster.
- ★Factor in material delivery fees and boom truck costs for multi-story buildings.
- ★Price ice and water shield separately since code may require it in valleys, eaves, and around penetrations.
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Common questions about roofing estimating
One roofing square equals 100 square feet. Contractors price per square to include materials, labor, and waste. Asphalt shingle roofing typically runs $350-$600 per square installed, while metal roofing ranges from $700-$1,400 per square depending on the panel profile and material.
Complex roofs with multiple hips, valleys, dormers, and penetrations require more labor and generate more waste. Add 15-25% to your base labor rate for complex roofs. Count each valley, hip, and penetration separately and add a per-unit cost for flashing and detail work.
For a simple gable roof, use a 10% waste factor on shingles. For a cut-up roof with hips and valleys, use 15-20%. Starter strips and ridge cap are estimated separately — plan on one bundle of ridge cap per 35 linear feet and one bundle of starter per 100 linear feet. Always round up your shingle order to the next full bundle and account for damaged or defective shingles.