How roofing is priced per square

A homeowner calls with a number from a neighbor: "They paid $400 a square." You measure 30 squares off the satellite image, multiply, and you are already wrong — the neighbor's roof was a one-story gable over a driveway, and this one is a 9/12 with two layers and a dumpster that has to sit in the street.

The base price per square is the least interesting number on a roofing estimate. The adders are the price.

First, what a square actually measures

A roofing square is 100 square feet of roof surface, not floor plan. A 2,000-square-foot house does not have 20 squares of roof. Pitch stretches the surface: at 6/12 the roof plane is about 12% larger than the footprint underneath it, and at 12/12 it is roughly 41% larger. Overhangs add more.

Pitch does two things at once: it raises the quantity you sell and the cost of every unit of it. Confuse the two and you underbid steep roofs twice.

Then order material on top of that with a waste factor — about 10% on a simple roof, more on a cut-up one.

The three adders that carry numbers

Steep pitch buys roof jacks, staging, planks and harnesses. Production drops sharply once a crew cannot stand up, so most shops step the adder around 7/12 and again around 10/12.

Tear-off layers cost labor and disposal, both per square, per layer. Mainstream architectural shingles run roughly 200 to 250 pounds per square, and heavy designer lines a good deal more. Check the spec sheet for the product you carry, because the dump bills by weight.

Ice barrier. The model residential code (IRC R905.1.2) calls for an eave membrane in areas with a history of ice forming along the eaves, running from the roof edge to a point at least 24 inches inside the exterior wall line. But there is no national building code: what binds your job is the code edition and local amendments your building department has adopted, and some jurisdictions require more. Ask the department, not a chart.

Everything else — valleys, boots, flashings, access, disposal, and the ventilation the shingle warranty often requires — you price by counting it.

Two 30-square roofs, side by side

Every dollar figure below is invented so the arithmetic is easy to follow; your own adders come out of your own costs (contractor hourly rate covers the labor side). Both roofs are 30 squares of the same architectural shingle at a base of $450 per square, tear-off and install.

Roof A, a single-story ranch: 5/12, one layer, straight gable, two pipe boots, a driveway wide enough for the dumpster and the boom truck.

Roof B, a two-story colonial: 9/12, two layers, six valleys, a masonry chimney, two skylights, six pipe boots, a jurisdiction that requires an eave ice barrier, no driveway, and 12 sheets of bad decking found after tear-off.

Same unit, same quantity, same shingle, a $9,520 spread — 70% more for the identical square count. Price Roof B off Roof A's number and you have given away a week of crew time.

Price the decking you have not seen yet

Decking is the one adder you cannot scope in advance, and the one that turns into an argument if you leave it out.

Put it in the estimate as a unit price with a quantity of zero: sheathing replacement, $95 per 4x8 sheet, billed as used, photographed before it is covered. The customer agrees to the rate on the day they sign, not on the day you are standing on a torn-off roof with rain coming. Same for rotten fascia and rusted drip edge.

That is a change order, and several states require change orders on residential work to be written and signed before the extra work starts. Thresholds and required wording differ by state; per square foot or per line item covers where to look yours up.

Storm work is a different business

Hail and wind replacement is scoped against a line-item estimate, not off your sheet — most often written in Xactimate. That is software sold by Verisk, not a price list the carrier maintains and not one you set. Verisk publishes localized price lists for hundreds of market areas on a monthly cycle, and the adjuster writes against the list for that area. Contractors license the same software, so you can write an estimate the adjuster compares line for line.

That changes four things:

• Someone else's number is the starting point. If your cost per square is above what the estimate allows, closing that gap is your problem.
• Payment may arrive in pieces. On a replacement-cost policy, carriers commonly pay actual cash value first and release the depreciation once the work is done and documented. An actual-cash-value policy has no second check — the depreciation is not covered. The deductible is the homeowner's. Which applies is in that homeowner's policy — read it.
• Supplements are normal, not a fight. Find what the original scope missed, document it, submit it. Photograph everything; the file is the argument. Approval is still the carrier's call.
• There are lines you cannot cross, and they are state law. In most states you may inspect, estimate and hand the estimate and photos to the insurer, but may not adjust or negotiate the claim for the homeowner without a public adjuster license. Separately, a large number of states — Texas, Colorado and Oklahoma among them — make it illegal to pay, waive or rebate the homeowner's deductible, with fines and in some places criminal exposure. Neither rule is uniform. Confirm both with your state insurance department, and have a lawyer read your storm contract before the season, not during it.

Putting your adders where you use them

Adders get left off because they live in your head while the base price lives on paper. In DoneQuote you load the base square price and each adder once as catalog items, so each one is something you pick, not something you remember.

Before you price the next roof

• Measure the roof plane, not the footprint, and apply the pitch factor
• Run every adder as its own line — a neighbor's per-square number is worthless
• Put decking in at zero quantity, priced per sheet, agreed before you sign
• On a storm job, read the policy and check your state's rules before you talk deductible