What Does a Commercial Flat Roof Contractor in McKinney, TX Actually Do Before Recommending a Coating?

The call came in on a Tuesday afternoon. A property manager off Eldorado Parkway wanted a quote from a commercial flat roof contractor in McKinney, TX for a 14,000-square-foot light-industrial building that had started leaking in two spots after a storm cell rolled through Collin County the weekend before. She wanted a coating quote, not a tear-off. She had read that coatings were cheaper than replacement, and her ownership group had told her to bring back numbers before they signed off on anything bigger. Fair starting point. We drove out the next morning.

The building was a single-story TPO roof, about twelve years into a fifteen-year manufacturer warranty. Two HVAC units sat on the north end. Drainage was passable but not great. From the parking lot you could tell the membrane had taken a beating from the last few summers. Up top, the story was more specific.

Where the inspection actually starts

Most small commercial owners think a coating quote means we walk the roof, count square feet, and email a number. That is not how this should go. On a flat roof, the question is never just “how much per square foot to coat it.” The question is whether the substrate underneath the membrane is dry enough, sound enough, and adhered well enough to hold a coating for the ten to twenty years the product is sold to deliver.

So the first thing we did was walk the perimeter and look at the seams. TPO seams are heat-welded. After a decade in North Texas sun, those welds get brittle along the edges. We found three places where the seam had pulled apart maybe a quarter inch — not catastrophic, but enough that water had been finding its way in for a while. Then we did core cuts. Two of them. Small plug samples through the membrane and into the insulation board underneath. The first one came up dry. The second one came up dark and heavy. The insulation under the leak area near the second HVAC unit had been wet for long enough to compress and start breaking down.

That changes the math on a coating entirely. You cannot coat over wet insulation. The moisture has nowhere to go, and within two summers you will see blistering, then delamination, then leaks worse than what you started with. The coating warranty would be void from the day it was sprayed.

What I told her over coffee in the leasing office

We came back down and sat in the leasing office. I sketched the roof on a piece of paper and circled the two wet zones. The choice was not “coating versus replacement.” The real choice was between three paths.

Path one: full tear-off and replacement. New TPO or a switch to a more impact-resistant system. Highest cost, longest disruption to the tenant inside, longest service life — twenty years plus on a fresh roof with a real warranty. For a building twelve years old in a market where the ownership group might sell in five, that math gets uncomfortable.

Path two: cut out the wet insulation in the two affected zones, replace it with new board, re-weld the membrane patches, then coat the entire roof with a silicone system. Medium cost. Around 35 to 45 percent of what full replacement would run, in the ballpark for a building this size. Service life of about ten to twelve years on the coating, with the option to recoat at year ten and add another seven to ten. Disruption to the tenant: minimal. Most of the work happens up top, on warm dry days, with low noise.

Path three: ignore the wet insulation, coat anyway, hope for the best. This is what some contractors will quote because it produces the lowest number on the email. I told her plainly that this path was the most expensive one of the three, because it ends in a tear-off in three or four years instead of fifteen.

She asked the question most owners ask at this point: “How do I know you are not just upselling me into the bigger number?” That is a reasonable thing to ask. We showed her the core samples. The wet one was visibly wet. You could squeeze water out of it on the table. There is no upsell argument that survives that, and there is no reason to invent one. Our broader roof repair work across the McKinney area is built on the same principle — diagnose first, recommend second, and never the other way around.

Why silicone, not acrylic, for this roof

Once she landed on path two, the next question was what kind of coating. There are four common families used on commercial flat roofs in North Texas: acrylic, silicone, polyurethane, and asphalt-emulsion. Each has a place. For this roof — a TPO membrane, occasional ponding near the drain on the south side, full sun exposure with no shade trees nearby — silicone was the right call.

Acrylic is cheaper per gallon and reflects well, but it softens under standing water. This roof had a small low spot near the drain where water sat for twenty-four to forty-eight hours after every heavy rain. An acrylic coating would lose adhesion in that spot within a few summers. Silicone handles intermittent ponding without breaking down. It costs more up front. Over a ten-year horizon it costs less.

Polyurethane would have been overkill here. It is the right choice for roofs with foot traffic — rooftop dining decks, mechanical access paths, anywhere people walk regularly. This roof saw a service tech twice a year for the HVAC units. Not enough traffic to justify the cost premium. Asphalt-emulsion we did not even discuss. It is a budget product for situations where reflectivity does not matter and the owner just needs a few more years out of a built-up roof. This was not that.

The detail work nobody talks about in the quote

The actual coating spray is the photogenic part. The part that determines whether the warranty holds for ten years is the detail work. Around every penetration — every pipe, every HVAC curb, every drain — the membrane gets reinforced with polyester fabric embedded in a base coat, then coated again. Seams get the same treatment. Edges get terminated against a clean substrate. If any of that is rushed, water finds the gap within two seasons.

I have seen jobs where the spray went on beautifully and the roof failed at a single pipe boot in year three. The owner thought he had a ten-year warranty. He had a ten-year warranty on the field of the roof. The penetrations were a separate detail and the contractor had not handled them right. That is a hard conversation. We walked the property manager through every penetration on her roof and showed her exactly how each one would be detailed. It took an extra hour. It was worth it.

What the numbers actually looked like

For her building, here is roughly how the three paths compared. These figures are illustrative and depend heavily on access, slope, deck condition, and current material prices. They are not a quote.

• Full tear-off and TPO replacement: in the range of 8 to 12 dollars per square foot, plus disposal and any deck repair.
• Targeted insulation replacement plus full silicone coating system: in the range of 3.50 to 5.50 dollars per square foot, including detail work and warranty.
• Spot leak repair only, no coating: a few thousand dollars now, with the understanding that the rest of the roof is on borrowed time.

She took the middle path. The ownership group signed off within a week. We did the wet-insulation cut-outs on a Monday, re-welded and let everything cure through Tuesday, and sprayed on Wednesday and Thursday under clear skies. The tenant inside the building never knew we were there except for one morning when the spray truck blocked two parking spots.

Where this kind of decision usually gets stuck

Most small commercial owners in McKinney, Allen, Plano, and the surrounding suburbs are not roofing experts. They should not have to be. But they are often given two extreme options — replace everything, or patch the leak and pray — when a middle path exists and serves them better. The reason they do not hear about the middle path is that some contractors are not equipped to do it well. Coating systems require specific equipment, training, and warranty backing from the manufacturer. Not every roofer carries it.

The other place this gets stuck is the question of whether the building will be held long-term. If an ownership group is planning to sell within three years, a coating buys time and presents better in inspection than a leaking roof at a fraction of the cost of replacement. If the building is being held for a decade or more, the coating economics get even stronger because the recoat option at year ten extends the timeline another decade. A full replacement still has its place — for roofs past their structural lifespan, for buildings with widespread wet insulation, for tenants who will not tolerate any disruption longer than a few hours. We talk through which situation applies before we talk price.

What owners with light commercial property ask us next

Plenty of the calls we get on this kind of work come from owners of small mixed-use buildings, strip retail, light-industrial bays, or commercial property attached to a residential portfolio. Their questions tend to cluster. Most want to know whether a coating will affect their insurance — the answer is usually no, but worth checking with the carrier before specifying the product. Some ask whether the reflectivity actually shows up on their summer cooling bill — yes, modestly, more visibly on older buildings with poor attic ventilation than on newer well-insulated ones. A few want to know whether they can do half the roof now and half next year — possible, but messier than it sounds, and usually not worth the savings unless cash flow is tight.

The question that comes up most often, though, is whether they really need a roof inspection before getting a quote, or whether a contractor can just look at photos. Photos help us scope a visit. They do not replace one. We will not quote coating work without core samples and a perimeter walk, because the wet-insulation question is too important to guess at. For owners thinking ahead, our take on the commercial and residential roof inspection process walks through what an honest visit covers, and a related read on the practical roof repair checklist we use across North Dallas covers the smaller decisions that come up between bigger ones.

What she said when we wrapped up

A month after the coating cured, the property manager called. The first heavy rain of the season had come through the previous night. She wanted to tell me the roof was dry. That was the whole call. Two minutes. It was the kind of follow-up that makes this work worth doing — a building that was leaking now is not, the tenant inside is paying rent without complaint, and the ownership group has a written ten-year coating warranty in their file. The roof will need attention again in a decade, probably a recoat, possibly a partial replacement depending on how the substrate holds up. That is a problem for 2036.

If you are weighing this kind of decision on a small commercial or light-industrial building anywhere in Collin County, the answer is rarely as simple as the cheapest quote. The right path depends on what your roof looks like under the membrane, not on top of it. A real commercial flat roof contractor in McKinney, TX will tell you that before quoting, not after the work fails. If you are looking for a starting point, you can reach our team through the contact page and we can talk through your roof before anyone sets foot on it.

The service side of what’s covered here lives on our commercial roofing in McKinney, TX page.