Roofing Estimate: How to Read One and What’s Fair

A stack of three roofing bids can look like they’re written in code, and that’s often the point. A vague roofing estimate that just says “replace roof, $14,500” gives a contractor room to cut corners you’ll never see until the roof leaks. A good estimate breaks the job into line items you can compare against the other bids and against what the work actually requires. Once you know what those line items are and roughly what each should cost, you can spot the lowball that skips the underlayment and the padded bid that charges twice for the same work. Here’s how to read one like a pro.

Part of our Roofing guide — explore the full guide →

Start With the Roof Size in Squares

Roofers measure in squares, not square feet. One square equals 100 square feet of roof surface. A typical single-story home has a roof of 15 to 30 squares; a large two-story can run 30 to 50. The estimate should state the roof size in squares, because almost every other number flows from it. If two bids disagree on the number of squares by more than a little, one of them measured wrong or is padding the count, and that’s the first thing to reconcile. Ask how they measured, whether from a satellite report like an aerial measurement service or by hand on the roof, and make sure the pitch and waste factor are accounted for.

The Line Items You Should See

A complete estimate spells out the work in stages. Look for each of these:

• Tear-off and disposal: removing the old roofing and hauling it away, usually priced per square or as a lump sum, often $1 to $2 per square foot including dumpster fees
• Decking inspection and replacement: a per-sheet price for any rotten plywood found under the old roof, commonly $70 to $120 per 4×8 sheet installed
• Underlayment: the felt or synthetic layer over the deck, plus ice-and-water shield at the eaves and valleys
• Drip edge and flashing: metal at the eaves, rakes, valleys, chimneys, and any wall intersections
• Shingles or roofing material: the main covering, by brand and product line
• Ventilation: ridge vent, box vents, or other exhaust to keep the attic healthy
• Labor: either bundled into the per-square price or listed separately
• Cleanup and warranty: magnetic nail sweep, debris removal, and both the material and workmanship warranties

If any of these is missing, ask about it. The most common corner cut is skimping on underlayment and flashing, the layers that actually keep water out, because they’re hidden once the shingles go on.

What a Fair Price Looks Like

For a standard architectural asphalt shingle roof, installed cost typically runs $400 to $700 per square, which works out to roughly $4 to $7 per square foot all in. On a 20-square roof that’s about $8,000 to $14,000. Prices vary widely by region, roof complexity, and material:

• Three-tab asphalt: the cheapest, around $350 to $500 per square
• Architectural (dimensional) asphalt: the standard, $400 to $700 per square
• Standing-seam metal: $900 to $1,600 per square
• Cedar or synthetic shake: $700 to $1,400 per square
• Slate or tile: $1,200 to $3,000-plus per square

A steep or cut-up roof with many valleys, dormers, and penetrations costs more per square than a simple gable because of the added labor and waste. Factor that in when a complex roof bids higher than a neighbor’s simple one.

Watch the Tear-Off and Decking Language

Two line items cause most disputes: layers and decking. First, confirm the bid includes a full tear-off down to the deck rather than a layover of new shingles on top of the old. A layover is cheaper but hides problems and voids some warranties. Second, decking replacement is the classic surprise charge. No one knows how much rotten plywood is under the old roof until it’s off, so a good estimate lists a per-sheet price up front and states how many sheets are included, so a change order is predictable rather than a shock. If the bid is silent on decking, get a written per-sheet rate before you sign.

Compare Materials Apples to Apples

A bid that just says “30-year shingles” tells you little. Modern architectural shingles are often marketed with lifetime limited warranties, and the real difference between products is wind rating, algae resistance, and the manufacturer’s warranty tier. Make sure all three bids quote the same shingle class, or at least note the differences. A lower bid using a builder-grade shingle isn’t cheaper if it’s a lesser product than the other two quoted. Ask for the exact product line and color so you’re comparing the same thing.

Warranties, Two Kinds

Every roof has two separate warranties, and homeowners confuse them constantly. The material warranty comes from the shingle manufacturer and covers defects in the product. The workmanship warranty comes from the contractor and covers installation errors, which are actually the more common cause of leaks. A strong estimate states both clearly, and a reputable roofer offers a workmanship warranty of at least a few years, often 5 to 10. A contractor who won’t stand behind their own labor is telling you something. Some manufacturers also offer enhanced system warranties when a certified installer uses a full line of their components, which can be worth asking about.

Red Flags in an Estimate

A few things should make you pause:

• A single lump-sum price with no line items or square count
• No mention of underlayment, ice-and-water shield, or flashing
• A demand for a large deposit, more than a third, before any work starts
• A price dramatically lower than the other bids, which usually means a layover or skipped steps
• No workmanship warranty or no proof of license and insurance
• Pressure to sign today for a “special” price

Ventilation and Accessories You Might Miss

Two categories quietly separate a complete roof from a patch job, and homeowners rarely think to check for them. The first is ventilation. A roof needs balanced intake and exhaust to keep the attic cool and dry, which prolongs shingle life and prevents ice dams in cold climates. A good estimate specifies the exhaust method, ridge vent, box vents, or a powered vent, and confirms adequate soffit intake. A roof re-covered without addressing bad ventilation bakes the new shingles from below and can void the manufacturer warranty, so make sure it appears as a line item rather than an afterthought.

The second category is the accessories that live at every penetration and edge: pipe boot flashings, chimney and skylight flashing, valley metal, drip edge, and starter and ridge-cap shingles. These are cheap individually but critical, because leaks almost always start at a penetration or a transition, not in the open field of the roof. An estimate that lists new pipe boots, new step flashing at walls, and proper starter and ridge-cap shingles is written by someone who understands where roofs actually fail. If the bid reuses old flashing to save money, ask why, because bent or rusted flashing is a leak waiting to happen under a brand-new roof.

Payment Terms and the Contract

Before you sign, understand the money and the paperwork. A reasonable deposit is a third or less of the total, with the balance due on completion; be wary of any contractor demanding half or more up front, which is a classic sign of an underfunded operation or a scam. The written contract should name the exact materials and colors, the total price, the payment schedule, the start and completion timeline, both warranties in writing, and confirmation of the contractor’s license and liability and workers’ compensation insurance. Ask for a certificate of insurance sent directly from their insurer, because if an uninsured worker is hurt on your roof, the liability can land on you.

Watch for the change-order language too. Since hidden decking rot is the most common surprise, the contract should state the per-sheet decking rate and require your written approval before extra charges are added. A professional roofer welcomes these terms because they protect both sides; a contractor who resists putting materials, warranties, and change-order rules in writing is telling you how the job will go. The estimate gets you in the door, but the signed contract is what you actually hold them to, so make sure everything you agreed to verbally appears on paper before work starts.

Making the Decision

Get at least three written estimates, put them side by side, and reconcile the differences line by line: squares, tear-off, decking rate, underlayment, flashing, material line, ventilation, and warranty. The right choice is rarely the cheapest and rarely the most expensive; it’s the one where you understand exactly what you’re paying for and trust the crew to do the hidden layers right. A clear, itemized roofing estimate is itself a sign of a professional, because the contractors trying to cut corners are the ones who’d rather you not see the details. Read it carefully, ask about anything missing, and you’ll buy the roof you’re actually paying for.