4 min read
How to Bid a Roofing Job
A roofing bid comes down to three numbers: how many squares, how much labor per square, and what the details cost. Details mean flashing, valleys, penetrations, ventilation and tear-off. Get those right and your bids hold up. Here's the process, step by step, for residential and commercial roofs.
Step 1: Get accurate measurements
One square is 100 square feet of roof surface. Ways to measure:
- From plans: use the roof plan and elevations, and adjust for pitch
- Aerial measurement reports: these are common on residential reroofs
- On site: measure the eaves and rakes, and verify the pitch with a level or pitch gauge
Pitch matters. A roof's real surface area is larger than its footprint. Multiply the footprint by the pitch factor for the roof slope, for example about 1.054 for 4/12 and 1.202 for 8/12.
Also measure linear footage of eaves, rakes, ridges, hips and valleys. Each one drives material such as drip edge, starter, ridge cap and valley metal.
Step 2: Add waste
Waste depends on how complicated the roof is. A simple gable roof needs less, and a cut-up hip roof with many valleys and dormers needs more. Use your own crew's history. Add waste to shingles and underlayment, not to the measured area on the proposal.
Step 3: Price tear-off and deck repair
- Number of existing layers to remove
- Disposal: dumpster size and number of loads, plus dump fees
- Deck replacement: price per sheet of OSB or plywood as a unit price or an allowance, since you can't see rot until tear-off
- Removing old flashing and vents
Put deck repair in the proposal as a unit price ("$X per sheet replaced"). This prevents arguments later.
Step 4: Materials
- Shingles, metal panels or membrane, by the square
- Underlayment, plus ice and water shield at eaves and valleys as code requires
- Starter strip, ridge cap, drip edge
- Flashing: step, counter, chimney, wall and headwall
- Pipe boots and vents: ridge vent, box vents and intake
- Fasteners, sealants, and accessories
Use current supplier quotes. Roofing material prices change often.
Step 5: Labor
Price labor per square using your crew's real rates, then adjust for:
- Steep pitch, which needs extra safety setup and is slower
- Stories, since higher roofs mean more handling and fall protection
- Complexity: valleys, dormers, skylights and chimneys
- Access: tight lots and landscaping protection
Include fall protection equipment and setup in the price. On commercial work, add crane or hoisting costs.
Step 6: Overhead, profit and warranty
Add overhead, profit, and the cost of any manufacturer warranty upgrade you're offering. Check your markup math with markup vs. margin for subcontractors.
Step 7: Write the roofing proposal
A good roofing proposal includes:
- The roof system: brand, product line, color and underlayment
- What gets replaced: drip edge, flashing, vents and boots
- Tear-off and disposal
- The deck repair unit price
- Gutters (included or excluded)
- Permit, cleanup, magnetic nail sweep
- Workmanship and manufacturer warranty terms
- Payment schedule and how long the price is valid
Itemized proposals help homeowners compare you fairly against a competitor's lump sum. See what to include in a contractor bid.
Residential vs. commercial roofing bids
- Residential reroof: Measure, inspect the attic for ventilation and deck condition, and present good, better and best options.
- Commercial (low-slope): Bid from plans and specs. Watch insulation thickness, tapered insulation, crickets, curbs, roof drains and the manufacturer's warranty requirements. Expect submittals and inspections.
Roofing bid checklist
- [ ] Squares adjusted for pitch
- [ ] Waste based on complexity
- [ ] Edge, ridge, hip and valley footage measured
- [ ] Tear-off layers and disposal priced
- [ ] Deck repair unit price stated
- [ ] Flashing and penetrations counted
- [ ] Safety and access priced
- [ ] Exclusions listed
Bid roofs faster
TradeBid's roofing estimating software drafts an editable, itemized roofing bid from your plans or roof drawings, then exports a branded PDF proposal. You check every quantity, and nothing goes out until you approve it. Takeoffs are included on the Journeyman ($300/mo) and Master ($850/mo) plans. Try TradeBid free for 7 days: every plan starts with a free trial that includes 3 bids and 1 takeoff, with a card on file. Start for $0.00 or read our roofing takeoff software guide.
FAQ
How do you calculate roofing squares? Find the roof area (footprint × pitch factor) and divide by 100.
How much waste should I add for shingles? It depends on the roof's complexity. Base it on your crew's actual waste on similar roofs.
Should I include deck replacement in the price? State it as a unit price per sheet, or as an allowance. You can't see hidden rot until tear-off.
What's the best roofing estimating software for small contractors? Look for itemized output, editable pricing and a clean proposal. TradeBid handles all three in the browser.
How do I bid a commercial roofing job? Follow the specs exactly: system, insulation, tapered layout, details and warranty. Bid from the roof plan and details, and list the submittals.