How to Read a Roofing Estimate: Every Line Item Explained

One price, sometimes with a short paragraph: "Tear off and replace roof with architectural shingles, $X." It's the most common format for small contractors and the hardest to compare. A lump sum is not automatically bad, and plenty of honest roofers write them, but a lump sum with no written scope means the scope is whatever the contractor decides it is on install day. If you get one, ask for the material list and the scope in writing before you compare it with anything.

The most useful format for homeowners. Every component is listed (underlayment brand, ice barrier coverage, flashing, ventilation, and so on), usually with quantities, but the price is a single total. You can't see what each line costs, but you can see exactly what's included, which is what you need to compare bids.

Every line has a quantity, a unit, and a price. Common in commercial work and in estimates generated by roofing software. It gives you the most information, and it also makes the contractor's markup on each item visible, which is why many residential roofers avoid it. If you're comparing a line-priced estimate against a lump sum, compare scope first and price second.

If a storm claim is involved, you'll also see an estimate from your insurance company, almost always generated in estimating software such as Xactimate. It's line-priced and very detailed, uses its own abbreviations, and separates replacement cost from depreciation. It's a claim valuation, not a contractor's bid, and it's covered in its own section below.

Drip edge is the L-shaped metal at the eaves and rakes that kicks water off the edge and protects the deck edge and fascia. The 2015 Michigan Residential Code, Section R905.2.8.5, requires drip edge at eaves and rake edges of shingle roofs, with adjacent pieces overlapped at least 2 inches. So a shingle bid without drip edge isn't a cheaper option. It's a code shortfall. The estimate should say new drip edge, list the lineal feet (eaves plus rakes), and ideally the color and profile.

An ice barrier is a self-adhering rubberized membrane at the eaves that seals around nails and stops water backed up behind ice dams from getting into the house. Section R905.1.2 of the 2015 Michigan Residential Code requires it in areas with a history of ice forming at the eaves, as designated by the local jurisdiction, and it must run from the eave edge to at least 24 inches inside the exterior wall line. In West Michigan's climate, expect it to be required; your local building department can confirm.

Read this line carefully, because "ice and water shield" alone says little. How far up the roof does it run? One 3-foot-wide roll at the eave may not reach 24 inches inside the wall on a house with deep overhangs, so some roofs need two courses. Is it also in the valleys, around chimneys and skylights, and at sidewalls? Code only sets the eave minimum; the valleys and penetrations are manufacturer or best practice. Brand names vary. Many roofers still say "Grace" generically; that product line is now sold as CertainTeed VYCOR.

Underlayment covers the rest of the deck beneath the shingles. The old standard is asphalt-saturated felt ("15-pound" or "30-pound" felt). Most estimates today specify a synthetic underlayment: lighter, stronger, more tear-resistant, and more forgiving if it's exposed to weather for a day or two during the job. Both can be code-compliant. What matters is that the product is approved by the shingle manufacturer, and for enhanced warranties, usually that it's the manufacturer's own branded product.

On an estimate, look for the brand or at least the type (synthetic vs. felt), and whether it covers the entire deck outside the ice barrier. On slopes from 2/12 up to 4/12, Michigan's code calls for a double layer of underlayment, so a low-slope section should be called out separately.

Starter shingles go at the eaves and often the rakes, under the first course, so the first row has a sealant strip and no exposed gaps. Manufacturer-branded starter is typically required for enhanced warranties. Some crews cut starter from field shingles, which can work if done to the manufacturer's instructions, but it's worth asking which approach the bid assumes, since it can affect warranty eligibility.

Where a roof meets a wall (a dormer, a second story, a garage wall), individual L-shaped pieces of step flashing are woven in with each course of shingles. Counterflashing covers the top of the step flashing, either tucked under siding or cut into masonry. Michigan's residential code requires flashing at wall and roof intersections and wherever the slope or direction changes.

Replace vs. reuse is the question to ask. Step flashing is often behind siding, and replacing it properly may mean removing and reinstalling some siding, which costs more. Some bids reuse it to avoid that. Section R908.5 of the code prohibits reinstalling existing flashings and metal edgings that are rusted, damaged, or deteriorated, so reuse is only acceptable on metal that's genuinely sound, and you should be told which it is.

Where a roof edge dies into a wall, a kick-out (diverter) flashing turns water away from the wall and into the gutter. The code requires a flashing that diverts water at that spot. A missing kick-out is a common cause of hidden wall rot, so look for it by name.

Chimneys get step flashing on the sides, apron flashing on the low side, and counterflashing set into the mortar joints above. On the high side, a chimney more than 30 inches wide (measured across the slope) requires a cricket or saddle under the code, a small peaked structure that sheds water around the chimney. A good estimate states whether chimney flashing is new, whether the counterflashing is cut into the mortar (reglet) or just surface-sealed, and whether a cricket is included where required. Caulk-only chimney "flashing" is a repair, not a flashing detail.

Plumbing vents get a flashed boot, usually a metal or plastic base with a rubber collar. The rubber collars crack with UV exposure long before the shingles wear out, which is why most replacement bids include new boots. Some estimates offer upgraded boots with longer-lasting collars or lead flashings. Exhaust fan caps, furnace and water heater flues, satellite mounts, and electrical masts are also penetrations; the estimate should say how each is handled.

A valley is where two roof planes meet in an inside corner, and it carries more water than any other part of the roof. Valleys are lined first (code requires a lining per the manufacturer's instructions, and self-adhering ice barrier is common), then finished one of three ways. An open valley leaves a strip of metal exposed down the center; code requires metal valley lining at least 24 inches wide. A closed-cut valley runs shingles from one side across the valley and cuts the other side back in a clean line. A woven valley interlaces shingles from both sides; it's common with three-tab shingles and generally not recommended for thick architectural shingles.

None is wrong if it's installed to the manufacturer's instructions. The estimate should say which method will be used, what's under it, and whether metal is included.

An allowance is a placeholder amount for something that can't be priced exactly until the work starts, most often deck replacement. Allowances are normal and honest when they're specific: a quantity, a unit price, and what happens if the actual is higher or lower. Look for language like "includes 3 sheets; additional sheets at $X each; unused allowance credited." The credit part matters. If the allowance is 3 sheets and only 1 was needed, you should see a credit or at least an explanation.

A vague allowance ("deck repair as needed, billed at time and materials") isn't necessarily dishonest, but it leaves you with no way to compare bids or check the bill. Ask for a unit price.

A change order is a written, signed change to the contract: added work, removed work, or a substitution. Legitimate change orders happen, most often for hidden rot, a second layer nobody could see, or a homeowner request mid-job. The protection is in the process. Every change should be written, priced, and signed before the work is done, ideally with photos of why. A contractor who says "we'll figure it out at the end" is setting up a disagreement.

Watch for estimates whose low price depends on predictable change orders: no deck line, no mention of layers, flashing marked "as needed." Those bids aren't cheaper; they're incomplete.

Read the exclusions section as carefully as the inclusions. Common exclusions: interior drywall and paint damage, gutters, siding replacement, structural framing repairs, removal of satellite dishes, and damage to driveways from delivery trucks. None of these is unreasonable to exclude, but you should know before signing, not after.

A commercial low-slope bid should start with what's actually on the roof. Core cuts are small samples cut through the roof to the deck to identify each layer: membrane type, cover board, insulation type and thickness, and whether anything is wet. A thorough bidder takes several and patches them. Many projects also use a nondestructive moisture survey (infrared, capacitance, or nuclear) to map wet insulation. If a bid was written without cores or a survey, ask what it's based on.

A recover installs a new membrane over the existing roof, often with a cover board. A tear-off removes the old system to the deck. Recovers can cost less and keep debris out of a landfill, but only when the existing roof is dry, sound, and not already layered. Building codes generally prohibit recovering over a wet or deteriorated roof or over a roof that already has two layers, so the core cuts and survey decide whether a recover is even possible. A bid that proposes a recover without that evidence is guessing.

The bid should state insulation type (polyiso is common), total thickness, and the resulting R-value. When a roof is replaced down to the deck, the energy code may require the new insulation to meet current levels, which can be significantly thicker than what came off. Your designer or local building department can tell you what applies. Tapered insulation creates slope to drains on a flat deck. It should come with a layout drawing showing slope (often 1/4 inch per foot or 1/8 inch per foot), crickets between drains, and the thickness at drains and high points, because that affects edge and flashing heights.

The membrane line should name the system (TPO, PVC, EPDM, modified bitumen, or a coating), the manufacturer, and the thickness in mils. TPO and PVC are commonly 45, 60, or 80 mil; EPDM 45, 60, or 90 mil. Thicker isn't automatically better for every building, but you need the same thickness across bids to compare them. Then the attachment method: mechanically fastened (plates and screws in the seams), fully adhered (glued), induction-welded, or ballasted. Attachment drives wind uplift performance and cost, and it should match the uplift design for your building and any insurer requirements.

Look for the base flashing height at walls and curbs (manufacturers set minimums, commonly 8 inches above the finished roof surface), how rooftop units and curbs will be handled (including whether units must be lifted), the edge metal and whether it's a tested system, drains and scuppers, and pitch pans or boots at pipes. If added insulation raises the roof, flashing heights, curbs, and door thresholds may need to be raised too; the bid should say so.

Commercial warranties vary more than residential ones. A manufacturer's no dollar limit (NDL) warranty covers repair of covered leaks without a cap tied to the original price, usually requires a certified installer, and usually involves a manufacturer inspection at completion. Material-only and limited-dollar warranties cover less. The bid should state the warranty type, term (10, 15, 20 years or more), wind speed coverage if any, and the contractor's own workmanship term.

Commercial bids usually reference submittals: product data, the manufacturer's warranty application, tapered layout drawings, and sometimes wind uplift calculations. Ask when they'll be delivered. Lead time for materials and the weather window matter, especially for adhered systems with temperature limits during Michigan's shoulder seasons.

Alternates are separately priced options (a thicker membrane, a longer warranty, added insulation). Unit prices are critical for wet insulation replacement: since no survey is perfect, the bid should state a price per square foot or per board to replace wet insulation found during tear-off, and deck repair prices per square foot. Those unit prices are how you compare the real exposure between bids.