What ARMA's Public Documents Actually Say About Shingle Waste
Updated: 9/5/2026
Many online sources cite a rule: “15% waste allowance for asphalt shingles, per ARMA.” It appears so often that it reads like an established standard — something ARMA (the Asphalt Roofing Manufacturers Association) published and stands behind. But checking ARMA’s own publicly available materials tells a different story, and it matters for getting the numbers right when you order.
What we checked: ARMA’s own public bulletins and FAQ
ARMA maintains a searchable list of public bulletins and an FAQ on their website. On 2026-09-03, both were retrieved and searched for any guidance on quantity takeoff, waste allowance, trim waste, or coverage for asphalt shingles. Neither the bulletin list nor the FAQ contains an entry addressing those topics. The “15% per ARMA” figure, in other words, does not appear in the ARMA materials we could verify.
ARMA does publish a separate document, the Residential Asphalt Roofing Manual, but it is sold rather than freely available. For this site, that manual was not purchased — so whether “15%” appears inside it remains unchecked. It is unchecked, not disproven. The point is: if you see “15% per ARMA” cited online, the source is not ARMA’s publicly available work.
What the NRCA actually cites: 2–10%, tied to roof shape
The most credible source on the topic points not to a flat percentage, but to a range that depends on your roof itself. Mark S. Graham, vice president of technical services at NRCA (the National Roofing Contractors Association), published guidance on this, discussing ARMA’s own Residential Asphalt Roofing Manual (retrieved 2026-09-03). Here is what he wrote:
“most asphalt shingle roof system installations will require anywhere from 2% to 10% excess shingles because of trim waste. The amount of trim waste depends on a roof’s configuration, including the number of valleys, dormers, hips and ridges, and roof system penetrations.”
The key word is “depends.” A simple roof — a rectangle with no valleys, no dormers, no penetrations for pipes or vents — needs fewer extra shingles to cover the cuts and waste. A roof with multiple dormers, valleys, and ridge details needs more. That is why there is a range of 2 to 10 percent, and why “15%” as a universal rule does not hold up.
The shingle bundle calculator uses 10% as its default — which is the top of the NRCA-cited range, a conservative assumption for a roof with some complexity. The waste field is adjustable, so you can lower it if your roof is simple or raise it if the details are intricate.
The bundle count question: it is not “3 bundles per square” everywhere
While waste percentage is debated, another common rule is just as questionable: “3 bundles of shingles per square” (where 1 square = 100 square feet of roof area). Like “15% per ARMA,” this sounds like a fixed standard. It is not.
Bundle count is determined by the manufacturer and the specific product line. Owens Corning, for example, publishes technical documentation for its fiberglass-based asphalt shingles (Section 073113, retrieved 2026-09-03). One Owens Corning product ships as 4 bundles of 16 shingles, covering 98.4 square feet per square (which works out to 98.4 ÷ 4 = 24.6 square feet per bundle). A different Owens Corning shingle type ships as 3 bundles of 20 shingles. Same manufacturer, two different bundle counts — and both look correct on the product packaging.
The shingle bundle calculator defaults to 24.6 square feet per bundle, which comes directly from the Owens Corning specification just cited. That field is also adjustable — if your shingles bundle differently, you can enter your actual coverage per bundle, and the math recalculates. The product documentation on your own shingles is the authority, not a round number that “sounds right.”
What actually decides: the roof you have and the shingles you buy
The circulating “15% per ARMA” and “3 bundles per square” rules are memorable because they are round numbers. But roof complexity varies, and shingle products vary, and neither of those variations shows up in a single flat percentage. When you order, three things matter: your roof’s actual complexity (the valleys, dormers, and penetrations that eat into coverage), the specific shingle product you are buying (which determines how many shingles fit in a bundle and how many square feet one bundle covers), and a reasonable waste allowance for the cuts you will make during installation.
The NRCA’s published range of 2–10%, tied to roof detail, is more honest than a universal rule. Your shingles’ bundle count, printed right on the package, is your actual starting point. The shingle bundle calculator takes both of those as inputs — roof waste percentage and bundle coverage — so you can work with the numbers you actually have in hand, rather than a memorized percentage that may not fit your job.