Commercial Roofing
Pick up a handful of grit from a scupper box and you are holding the surface of the roof. Mineral granules are the sun shield on a modified bitumen cap sheet, and when they pile up in drains the asphalt underneath is coming bare. Add a cap that feels tacky on a hot afternoon and a lap line that has lifted at its edge, and you have the typical first signs of a roof giving out at the surface.
Modified bitumen is asphalt sheet blended with a polymer so it flexes instead of cracking. In Edinburg, TX, flat roofs bake for months and then absorb tropical downpours, and a layered, flexible build can handle that cycle if the building suits it. Our work covers new installation, repair, and the judgment of whether a worn cap can be restored or must come off. First we trace where the water entered and how far it ran between plies.
Two modifiers dominate. Styrene-butadiene-styrene, SBS, is rubberlike and lets the sheet stretch and recover. Atactic polypropylene, APP, is plastic-like, stiffer, more heat resistant and kinder to sunlight. Both ride on a polyester or fiberglass reinforcing mat, and both come smooth or topped with granules.
With May to October designated as heat-safety season for the Valley, a sheet that holds its shape in sustained heat earns its keep. The decision still rests on the application method, the manufacturer's allowances and the roof that exists today, because a new sheet has to bond to whatever it lands on. We read the old roof before recommending either one.
The system is a stack. A base sheet is nailed down or glued to the deck or insulation, then one or more plies are bonded over it, and a granule-surfaced cap goes on last to protect the asphalt from sunlight and give some reflectivity. A defect in one layer still meets the layer beneath it.
The layers that make the roof tough also hide its trouble. Water that gets in at a lap can slide between plies and drip somewhere far from the entry. We trace bare mat, missing granules and soft spots back to where they began, and the commercial roof inspection record separates cosmetic wear from real exposure. Cores show how many plies remain and whether water reached the insulation. The core holes are patched with matching material and sealed the same day. Wall and curb flashings are made of reinforced sheet laid in matching adhesive, and each stage is checked before the next goes over it, because a void under a finished flashing cannot be reached afterward.
With a torch, a crew heats the underside of each roll with propane as it unrolls. With a hot mop, the sheet is pressed into heated asphalt. Cold systems rely on adhesive, and some sheets carry their own peel-off backing. Speed, odor, fire risk and deck tolerance differ among the four.
Flame and hot asphalt call for fire watches, extinguishers, shielded edges and a clear zone around the work. Over occupied space, a wood deck or a combustible wall detail, we tend to choose a cold or self-adhered method instead. Valley heat shapes the day as well: asphalt softens on a hot afternoon, crews slow down, and fresh sheet scuffs underfoot, so the heaviest work starts early. Torch work in particular is planned around wind, since a gust can bend the flame across a roll edge and leave a thin, unbonded strip that shows up as a lap leak.
The usual list is short. A lap that was never fully sealed lifts. A blister swells where trapped air or moisture expands in the sun. A ridge appears where a lower seam shows through the cap. Bare asphalt left by granule loss oxidizes and cracks. Each opens a route to the insulation.
Large hail crossed the McAllen-Edinburg-Mission-Pharr area in spring 2012, and a cap bruised by hail can crack months afterward. We open blisters only when the probe or the moisture reading calls for it, cut out damaged cap and reseal laps with compatible material. Where standing water sits behind the damage, the ponding water repair comes first, since the sheet will fail again at the same low spot.
Walking wears granules fast, and the route from the roof hatch to the nearest unit becomes a bare stripe within a few seasons. Dropped tools, dragged hoses and equipment feet add to it. Walk pads along the route, protection under pipe stands and a fix for the unit supports reduce the damage.
A sound, dry cap can be restored with a coating that hides worn granules and brings back a reflective face. Either silicone or acrylic will cover small defects, after an adhesion test on the old surface, because coating over loose granules just peels. Where equipment crowds the roof, our curb and support work goes first. The area coated, date, product and test results go into the roof record, so a later inspection can tell original roof from restored roof.
Seasonal timing matters on this system. A sheet laid on a cool, damp morning bonds poorly, and one laid at midday on a dark deck can soften underfoot. We schedule installs for dry early hours, shade fresh seams from direct sun until they set, and stage rolls out of the heat so they unroll flat. Laps are rolled firm and inspected the same day, and any questionable lap is resealed before the crew leaves it. Photographs of the finished laps, edges and flashings go into the roof record, with the date and weather noted.
The weather service records 50-to-70-mph gusts and minor damage in Pharr during Hurricane Dolly, and the city and TxDOT describe the I-2 and I-69C interchange as a major link between the Valley's east-west and north-south expressway corridors. Edinburg's economic development group lists distribution and warehousing among local employers, and a low-slope roof on a building like those is a candidate for a multi-ply system. A building's use still does not tell us what its roof is.
We serve Edinburg and Pharr. Edinburg works from the 2018 editions of the building and energy conservation codes, and we set modified bitumen against a single-ply like TPO using the building's use, access, fire rules and cost.
SBS flexes through temperature swings and APP resists heat and sun. The existing roof, the application method and the specification usually pick the winner, and we say which fits.
With strict fire controls it can be done, but cold-applied or self-adhered systems remove the flame. The property manager and the insurer both get a say.
The mineral shield is wearing off and exposing asphalt to the sun. A little is normal, and bare areas signal aging that a coating or a cap repair may address.
Yes, when it tests dry and the surface is clean and sound. Adhesion tests and a moisture scan come first.
The lap is cleaned, primed or warmed as the system allows, and compatible material is pressed in. A lap that keeps lifting tells us something is moving or ponding close by.