Algae-Resistant Re-Roof, Creekside

The Situation

A two-story home built around 1999 in the Creekside subdivision off Rand Road at Roaring Creek Drive, on the south side of Garner a few minutes from Rand Road Elementary and the Lake Benson Park trailheads. Creekside went up in a single late-1990s wave, so the street is full of original builder roofs that all aged into their third decade at once, and this owner had watched the north face of theirs darken streak by streak each summer until a neighbor's freshly replaced roof made the contrast impossible to ignore. The lots back up to the wooded creek buffer that gives the neighborhood its name, which keeps the shaded slopes damp long after a rain. The home sits inside town limits, so the permit runs through the Town of Garner Inspections department under the 2018 North Carolina Residential Code.

The roof was a roughly 25-year-old 3-tab system whose north and northeast slopes had gone dark with Gloeocapsa magma, the airborne cyanobacteria that settles on the slope getting the least direct sun and the longest drying time. In Garner that slope almost never fully dries: the creek buffer behind the lots and the broad humid bowl off Lake Benson and Lake Wheeler keep the shaded planes damp, which is exactly the standing-moisture and organic-film condition the algae needs to take hold. Once colonized, the organism feeds on the limestone filler in the shingle mat and grows a dark protective sheath against UV, the black streaking the owner could see from the yard. That sheath drops the slope's reflectivity, so the north face ran hotter than it should and aged the asphalt faster, while the feeding action worked the protective granules loose and washed them off with every rain. The streaking is the cosmetic symptom; the granule loss and the cooked, brittle mat underneath are the structural failure, and on this roof the choked attic ventilation feeding the moisture had pushed both past the point a cleaning could honestly save.

The System We Installed

Full tear-off of the old 3-tab to the deck, then a GAF Timberline HDZ architectural shingle system installed to the 2018 NCRC, specified for the algae problem it was solving: HDZ carries GAF Time-Release algae-fighting technology, copper-microsite capsules baked through the granules that meter copper out over years, backed by the 25-year StainGuard Plus algae-protection limited warranty rather than the shorter coverage of an unprotected shingle. A self-adhered ice-and-water membrane went into all three cleaned-out valleys and at the eaves, synthetic underlayment replaced the old felt across the field, and the two soft north-plane decking sheets were cut out and replaced with new OSB nailed off with ring-shank fasteners before the new system went down. The fix that makes the shingle warranty mean something was the ventilation: the painted-over soffit intakes were opened back up and a continuous ridge vent was set so the attic finally breathes on a balanced intake-at-the-eave, exhaust-at-the-ridge path that pulls the trapped humidity out instead of holding it against the slope.

Timeline & Constraints

Free on-site inspection within a day of the call, with the streaked north slope, the blocked soffits, and the silted gutters all photographed so the owner could see why a pressure-wash alone would not hold. The tear-off and full re-roof ran a single working day with a five-person crew once the decking and ventilation scope was set. The crew worked the dry window deliberately: the shaded north plane needs the deck bone-dry before the ice-and-water membrane and underlayment go down, so the start was held to the morning after the dew burned off and the exposed deck was dried and tarped at the prior afternoon's break rather than left open to the damp creek air overnight. A magnetic nail sweep of the drive and beds closed the job, and Town of Garner Inspections cleared the final.

The Outcome

Before: a 25-year-old 3-tab roof with a north face black with algae, granules washed into the gutters, two soft decking sheets, and an attic choked off from the air that would have slowed the whole process. After: a clean Timberline HDZ roof with copper-microsite algae protection on the very slopes that had failed, a corrected balanced-ventilation path drying the assembly the algae had lived on, and the valleys cleared so water runs instead of standing. The owner now has the 25-year StainGuard Plus algae warranty on the material and our 25-year workmanship warranty on the install, and that workmanship coverage transfers once to a new owner, a documented selling point on a Creekside block where every other house is staring down the same end-of-life north-slope streaking and buyers shop for the home that has already handled it.