How do I use a new roof cost calculator?
Short answer. Start with your home's footprint, add the overhangs, multiply by a pitch factor to get the true roof area, divide by 100 to get squares, and add 10 to 15 percent for waste. Then place that number in the right North Georgia size band instead of multiplying by a price per square you found online.
Step 1: Footprint
Measure the outside of the house, or use the footprint from your county tax assessor record. Include an attached garage and covered porches that share the roof.
Step 2: Overhangs
Add the eaves and rakes. With 1 foot overhangs, add 2 feet to each overall dimension.
Step 3: Pitch factor
Multiply the flat area by the factor for your pitch:
- 4/12: 1.054
- 6/12: 1.118
- 8/12: 1.202
- 10/12: 1.302
- 12/12: 1.414
Step 4: Squares and waste
Divide by 100 to get squares. Add about 10 percent for a simple gable or 15 percent for a hip roof with valleys.
Step 5: Place it in a band
- Smaller roofs on simple homes: roughly $7,000 to $11,000.
- Most suburban homes: roughly $8,000 to $16,000.
- Large roofs: roughly $15,000 to $25,000.
- Steep or cut up roofs: $20,000 and up.
Step 6: Budget the unknowns
Set aside a cushion for decking replacement, a second layer of shingles, or chimney flashing that needs rebuilding. A good contract prices those items in writing. See how roofers measure a roof for the professional version of this math and roof replacement cost in Georgia for the full picture.