Asphalt Shingle Roofing
The coarse grit collecting in the bottom of your downspout is the roof filing a report on itself. Those are ceramic-coated mineral granules, and they are not decoration. They are sunscreen. An asphalt shingle is three things doing three jobs: a thin fiberglass mat that gives it strength and holds its shape, refined asphalt over the mat that does the actual waterproofing, and granules pressed into the asphalt that take the ultraviolet punishment so the asphalt underneath does not. Once enough granules have washed into the gutter, the asphalt is weathering directly, and the countdown that follows is short. Older roofs may still carry organic shingles built on a felt mat, which absorbed moisture and grew heavy in humid air; that construction has largely left the market. APC Roofing installs, maintains and replaces asphalt shingle roofs in Florida, Kansas, Missouri and Colorado, and the material behaves the same way in all four — it is only the weather that changes what kills it first.
Aging follows a predictable path once you know what to watch for. Heat and sunlight cook the light oils out of the coating. The shingle loses flexibility, edges begin to curl or cup, and granule loss accelerates. Exposed asphalt then weathers directly, cracks open across the surface, and the mat is eventually left facing the weather alone. In humid air, dark algae streaking arrives on top of all this; it is cosmetic rather than structural, and granules blended with copper resist it. What speeds the whole sequence up is heat from below. An attic that cannot breathe bakes the shingles from the underside, and a roof rated for decades can shed years without anybody noticing. The code baseline is one square foot of net free ventilating area for every 150 square feet of vented attic space, and the more familiar 1:300 ratio is an exception, earned by putting 40 to 50 percent of that area high — within three feet of the ridge — with the balance at the eaves. Intake and exhaust have to be balanced. Ridge vent added over blocked soffits does very little except pull conditioned air out of the house.
Two published numbers separate one asphalt shingle from another, and both are worth understanding because both are conditional. Impact resistance is graded Class 1 through Class 4 under UL 2218. Each grade is a steel ball of a set diameter released from the height that gives it roughly the energy a natural stone of that size would carry, struck in the same place twice, and the covering passes only if nothing cracks, splits or separates. The ladder runs 1.25 inches at twelve feet, 1.5 at fifteen, 1.75 at seventeen, and two inches at twenty feet for the top grade. Set that against the field. A severe thunderstorm warning goes out at one-inch hail, and one inch is roughly where a plain three-tab starts sustaining functional damage; laminated products carry through to about an inch and a quarter, and the heavier ones nearer an inch and a half. The grade earns its cost where big stones are a seasonal certainty rather than a rare event, which describes Colorado, Kansas and Missouri far better than it describes coastal Florida.
Wind resistance is the second number. Under ASTM D7158, Class D corresponds to a 90 mph basic wind speed, Class G to 120 and Class H to 150. Every one of those classes was earned by a sample fastened precisely as the manufacturer specifies, which is why fastening decides whether you own the rating you paid for. Nails belong inside the narrow zone printed across the shingle; one driven above that band holds a single layer instead of two. And the count is not fixed — four nails per shingle covers a standard installation, but the manufacturer's top wind warranty, usually 130 mph, generally calls for six, together with a bonded starter course at the eaves and rakes. Nothing on a roofing quote is cheaper to upgrade or easier to skip.
Beyond that, asphalt rewards two unglamorous habits: keep air moving under the deck, and keep the surface clear of debris and overhanging branches. Cooler asphalt holds its oils longer, and clear valleys shed water instead of holding it against the courses. Together those are most of the difference between a roof that reaches its service life and one that quietly gives up early. For the two product families built on this material — the flat three-tab strip and the laminated product sold as architectural — see the page for each.
