Round Up or Round Down: Compare the Square Count in Each Roof Bid

A roof bid usually gives you a number of squares before it gives you a price. A square is 100 square feet of roof surface, and the count is the base for almost every line that follows: shingles, underlayment, drip edge, nails and crew hours. When two bids measure the same house, the square counts often still differ, and the difference is frequently not a measuring error. It is a rounding choice, a waste allowance, or a bundle rule that the bid never prints.

This page is for the stage where you have two or more bids in hand and one question is still open. The question is how each roofer turns the raw measurement into the number they order and charge against. You can ask it in a few sentences, and the answers will line up on one sheet.

Where the raw measurement ends and the bid begins

Most roofers measure the roof planes, add them up in square feet, and divide by 100. A house with 2,140 square feet of roof planes is 21.4 squares. That is the raw figure. Somewhere between 21.4 and the number on the page, the roofer makes at least three decisions: whether to round, how much waste to add, and whether to round again when the shingles are counted into bundles.

None of these steps is wrong by itself. Rounding up to the next whole square is common because shingles are sold by the bundle and the crew cannot tear off a fraction of a square. Adding waste is standard because cuts at hips, valleys and chimneys throw away material. The trouble is that a bid can do all three without saying so, and the next bid may do none of them. The total looks cheaper or dearer for reasons nobody wrote down.

Three numbers to pull from each bid

Before you compare totals, write three figures from each bid on the same sheet. Ask the roofer for them if they are missing.

• Measured squares. The raw count from the roof planes, to one decimal place.
• Ordered squares. The count the shingle order is built on, after rounding and waste.
• Bundles. The number of shingle bundles on the order, and the bundles-per-square figure the roofer used.

If a bid shows only one total square count, the other two numbers are hidden inside it. Ask for them directly. A roofer who measured carefully should be able to say the raw figure without looking anything up.

Why bundles per square matter

Architectural shingles are sold in bundles, and a common rule of thumb for standard architectural shingles is three bundles per square. That is a starting point, not a fact about every product. The product data sheet and the bundle label set the real number for the shingle that goes on your roof. Hip and ridge shingles usually come in their own packaging and are counted separately from the field shingles.

A bid that states a square count but does not name the bundle count leaves the crew to decide, on the day the pallet lands, whether the material will stretch. A short order on a steep roof with several hips is a common reason for a second delivery, and a second delivery means a second truck at your curb. Ask which bundles-per-square figure the bid uses and whether it matches the product on the wrapper.

Waste is a percentage, so ask what it is a percentage of

Waste is often written as a percent added to the measured squares. Ten percent on 21.4 squares is about 2.1 squares more, so the order becomes roughly 23.5 squares before rounding. Some bids use a fixed waste number instead. Others add waste only to the field and not to the hips, valleys or ridge. Each method can be reasonable, but they produce different orders and different totals.

Ask each roofer three plain questions. What percent is the waste? Is it added to the measured squares or to the rounded squares? Does it cover the ridge and hip material, or only the field?

Rounding rules, one by one

Rounding changes the bill more than most homeowners expect, because it moves the whole material list at once. A roof of 21.4 squares rounds to 21 if the roofer rounds to the nearest whole square, and to 22 if they round up. If the roofer rounds to the nearest half square, the figure lands on 21.5. These are small steps on paper. Each one multiplies through shingles, underlayment, starter strip and nails.

When you compare, ask whether the bid rounds the measured count, the ordered count, or both, and whether it rounds up in every case or only when the fraction is large. The answer tells you whether two totals are measuring the same roof.

Pitch and the steep charge

St. Louis roofs are often steeper than they look from the sidewalk, and a steep pitch can change the labor line without changing the square count. Some roofers add a steep charge once the pitch passes a set figure. Others fold it into labor. Two bids with identical square counts can carry different crew costs if one roofer prices a steeper pitch than the other. Ask each roofer what pitch they measured and where their steep charge starts. The pitch is usually written as rise over run, and that is the number to put in your file.

Write the comparison on one sheet

Make a sheet with one column per roofer and these rows: measured squares, waste percent, ordered squares, bundles per square, total bundles, ridge and hip count, and whether a steep charge applies. Fill it from each bid before you look at the total. When a row is blank, that is your question for that roofer.

Once the rows are filled, the total is easier to read. Two roofers may still differ on price, and that is a fair difference to weigh. What you want to avoid is a gap that comes only from rounding or waste, because that gap says nothing about the roof or the crew.

What to ask each roofer

1. What is the raw measured square count, to one decimal place?
2. Do you round the measured count, the ordered count, or both? Do you round up, to the nearest whole square, or to the nearest half square?
3. What waste percentage is applied, and does it cover the hips and ridge?
4. How many bundles per square does this order use, and does that match the product data sheet?
5. Where does your steep charge start, and what pitch did you measure?
6. If the order runs short partway through, who pays for the extra bundles?

Write each answer next to the roofer's name, in their words. If a roofer answers one question with another total, ask again for the single figure. If you want a second check on the arithmetic, call the Keys Roofing office at (314) 220-2333 and ask for the square count and bundle figure used on your own bid, then compare it with the others on the sheet.