Estimating roofing cost means building up from the measured quantities to a bid price. The build up is: materials + labor + equipment + subcontractor = direct cost, then + overhead = job cost, then + profit = bid price. Each layer has a range, not a fixed number, and your actuals depend on roof area, pitch, tear off, layers, access, and the roofing system you choose.
What You Are Pricing
A roofing estimate covers five scopes: the tear off and disposal of the existing roof, the deck prep and repair, the underlayment and ice and water shield, the finish roofing material, and the flashings and trim. Each one has a unit and a production rate, and missing any of them is how roofs lose money.
Measure the roof in squares. One square equals 100 SF of roof surface, not floor area. A 2,400 SF ranch at 4/12 pitch has about 2,500 SF of roof area, or 25 squares. The same house at 8/12 pitch has about 3,100 SF of roof, or 31 squares, because pitch multiplies the area. Always apply the pitch multiplier: 4/12 runs 1.054, 6/12 runs 1.118, 8/12 runs 1.202, 12/12 runs 1.414.
Separate the system. Asphalt shingles, metal standing seam, TPO low slope, and tile each price differently. Asphalt is sold and placed by the square and is the residential baseline. Metal is by the square or linear foot of panel. TPO and EPDM are priced by the square on low slope roofs. Tile runs by the square but the labor is two to three times asphalt.
Direct Cost Buildup
Materials. Architectural asphalt shingles run $90 to $160 per square for the material. Synthetic underlayment runs $20 to $40 per square, felt runs $8 to $15. Ice and water shield runs $70 to $110 per square and goes in valleys, eaves, and penetrations. Starter strip and drip edge run $8 to $15 per 10 foot piece. Ridge cap and vent run $30 to $60 per linear foot of ridge. Metal standing seam runs $250 to $600 per square for panels and clips. TPO membrane runs $120 to $220 per square. Concrete tile runs $300 to $500 per square, clay tile $400 to $800.
Labor. Tear off runs 0.5 to 1.5 hours per square depending on layers and how the old roof comes off, with a 3 person crew. Install of architectural shingles runs 0.6 to 1.0 hour per square with a 4 to 5 person crew on a walkable pitch. Steep pitch above 8/12 adds 30 to 80% to the labor. Metal standing seam runs 1.5 to 3 hours per square. TPO runs 0.5 to 1.0 hour per square with a certified crew. Tile runs 1.5 to 3 hours per square. Burdened wage runs $22 to $45 per hour for a roofer, $16 to $28 for a laborer.
Equipment. Dumpster and disposal runs $400 to $800 per 30 yard container, and a 30 square tear off typically fills one. A roofing nailer, compressor, and ladder hoist rent at $150 to $300 per job. A boom lift for steep or cut up roofs runs $400 to $800 per week. Crane time for tile or panel deliveries runs $250 to $500 per hour.
Subcontractor. Many crews are 1099 subcontractors on a per square basis, $80 to $180 per square installed for shingles. Plumbers and HVAC for flashing around vents and curbs. Chimney repointing or masonry work subbed out at $40 to $80 per hour. Permits and inspections run $200 to $600 depending on jurisdiction.
Step by Step Cost Estimate
For a representative asphalt shingle reroof, 2,400 SF house, 4/12 pitch, 26 squares, one layer tear off:
- Quantities: 26 squares shingles, 26 squares underlayment, 6 squares ice and water, 240 LF drip edge, 120 LF ridge vent and cap, 1 dumpster.
- Materials: Shingles 26 sq at $130 = $3,380. Underlayment 26 sq at $30 = $780. Ice and water 6 sq at $90 = $540. Drip edge and starter $260. Ridge vent and cap 120 LF at $45 = $540. Fasteners, pipe boots, sealants = $180. Total materials = $5,680.
- Labor: Tear off 26 sq at 0.8 hr = 21 hr. Install 26 sq at 0.8 hr = 21 hr. Flashing and detail 8 hr. Total 50 hr x 4 person crew at $30 blended = $6,000. Or subbed at $130 per square = $3,380.
- Equipment: Dumpster $600, nailer and hoist $200. Total equipment = $800.
- Subcontractor: Permit $350. Total subcontractor = $350.
- Direct cost: $5,680 + $3,380 (subbed install) + $1,260 (tear off labor) + $800 + $350 = $11,470.
Factors That Move the Number
Tear off and layers are the biggest swing. A clean one layer tear off is fast. Three layers of old shingles, with tar and gravel at the bottom, doubles the tear off labor and the disposal. Always count layers at the bid walk and price the disposal by the dumpster, not a flat allowance.
Pitch and access. A 4/12 walkable roof is the baseline. Above 8/12 you need scaffolding, planks, or a lift, and production drops 30 to 60%. A 12/12 cut up roof with dormers and valleys can double the per square labor of a simple gable.
Cut up roofs. Hips, valleys, dormers, and skylights slow installation. Every valley adds flashing time and waste. Every skylight adds step flashing and curb work. A simple gable is one square per hour; a cut up Victorian can be 0.4 squares per hour.
System choice. Asphalt architectural is the baseline. Designer and impact resistant shingles run 1.5 to 2 times standard. Metal standing seam runs 2 to 3 times asphalt. Tile runs 2 to 4 times. TPO on low slope runs $5 to $9 per SF installed.
Deck condition. Soft or rotten plywood deck is common under old roofs. Price deck replacement as a separate line at $60 to $100 per 4x8 sheet installed. Do not bury it in the square price or you eat it.
Region and code. Coastal and high wind zones call for more nails, starter, and sealant, plus a wind warranty test. Snow country needs ice and water on full eaves and valleys, not just the first three feet. Each code bump is a material line.
Common Mistakes
- Using floor area instead of roof area. A 2,400 SF house at 8/12 pitch is 31 squares, not 24, and that is 30% more material and labor.
- Counting squares without the pitch multiplier on cut up roofs. The hip and valley area adds squares.
- Underestimating tear off. Three layers and a gravel surface is not one layer of shingles.
- Using a markup instead of a margin. 10% markup on $11,470 gives $12,617, while 10% margin gives $12,744. The gap loses money on tight bids.
- Forgetting to burden the labor rate before marking up. Roofers carry high workers comp, which is part of the real cost.
- Setting one profit number for every job. A steep cut up reroof with three layers is not the same profit as a simple gable new build.
- Not pricing the deck replacement, flashing, and trim. They are real and they are where roofers lose money.
Putting It Together
Take the $11,470 direct cost from the worked example. Apply overhead at 15% of direct cost = $1,721. Apply profit at 10% of (direct + overhead) = $1,319. Bid price = $14,510. That is about $6.05 per SF of roof area, or $558 per square, which sits in the common architectural asphalt range of $4.50 to $8.50 per SF installed.
Metal standing seam typically runs $10 to $18 per SF installed. Concrete tile runs $9 to $16 per SF. TPO low slope runs $5 to $9 per SF. Use these ranges as a sanity check against your build up, not as a substitute for measuring the actual squares, tear off layers, pitch, and access yourself.
Numbers are illustrative and vary by region, project size, and material choice. Use them as a sanity check, not a bid. Use your actual overhead and target profit from your books.