Seam Failure Repair in Sherman, TX

A membrane seam is two sheets joined edge to edge. On a thermoplastic roof the join is a hot-air weld. The two surfaces melt together and cool into one piece. On a rubber roof the join is tape or adhesive. On a modified bitumen roof it is a heated lap. In each case the seam is the weakest line in a field of strong material.

A seam carries every stretch the roof makes. In Sherman, TX, a roof can ride from 113 F in summer down to -3 F in winter. The sheet grows in heat and shrinks in cold, and the seam takes the pull. Over years that pull opens a gap at one end. The gap lets water in. We locate it with a probe before anyone reaches for a patch.

Seams fail in a few ways. A weld may never have fused fully, leaving a cold joint that looks closed. Heat cycling may peel the edge of a lap. Foot traffic may crush the lap against a hard substrate. Dirt may have been trapped in the weld. Or the sheet may have shrunk and pulled the lap apart.

Each cause leaves a clue. A cold weld lifts easily with a probe. A peeled lap shows a clean, curled edge. A crushed lap shows a flat, shiny line. A shrunk sheet pulls away from corners and flashing first. The clue tells us whether the seam is a single local failure or part of a pattern along the whole roof. A pattern means the next seam may open next.

Age matters, but it is not the whole story. A roof ten years old with tight seams is in better shape than a younger roof with cold welds. We judge each seam by test, not by date.

Seams differ by system, and so do repairs. On a TPO roof or a PVC roof, a failed seam is cleaned and re-welded with hot air, or covered with a welded cap strip. On an EPDM roof, the lap is cleaned, primed and taped with splice tape, or a patch is adhered over the gap. Modified bitumen laps are reheated or sealed with a compatible mastic.

The wrong method on the wrong sheet fails quickly. A tape product does not bond to a thermoplastic sheet. A hot-air weld does not work on cured rubber. For that reason, the first visit identifies the membrane. We read the underside of a lifted edge, test the surface and check any paperwork the owner holds. Then we choose the material.

A seam leak is rarely one seam. We probe the full run of each lap in the suspect area, using a blunt tool that tests the edge without cutting it. We mark every open section with chalk and photograph it. A weld that looks closed from above may open under the probe.

Then we scan for moisture. Water that enters at a seam moves along the top of the insulation, often in a line. The scan shows where it went. Core samples confirm how wet the insulation is. An infrared moisture survey maps the whole roof in a single pass, which helps on a large industrial roof where a leak may be far from the opening. Seams that have been open for a season often have wet insulation under them, and wet insulation is cut out before the seam is closed.

Sherman receives about 44.3 inches of precipitation a year. Rain finds an open seam on the first storm. Spring brings the heaviest storms, with North Texas tornado counts cresting in April and May, and the same storms bring hail. A report northwest of Denison on June 8, 2025 measured stones at half-dollar size. Hail can crack a weld or crush a lap without puncturing the sheet, so the damage shows only on close inspection.

Cold stresses seams too. A sheet that has shrunk in January pulls hardest on its laps. Snow and ice add weight to a roof and to the drains that carry meltwater. In January 2025 a few Grayson County spots held nine to eleven inches of snow. After a freeze, we re-probe the seams we repaired, since new welds are the first to show a pull.

The repair follows a fixed order. The area is cleaned and dried. Wet insulation is cut out and replaced. The seam is prepared, with the surfaces scrubbed and trimmed back to sound material. The weld, tape or patch goes on. Then the repair is probed and the edge is checked for a continuous bead.

Where seams have failed in a pattern, we do not patch each one. We compare the cost of repair with the cost of a recover or replacement, and we show the numbers. A roof with seams opening along a wide area has often reached the end of its service life. Smaller problems around a corner or a curb may be a matter of flashing failure instead, and we check the two together because they leak in the same places.

Seam work takes place on buildings that are in use. Food processing, semiconductor and laser plants fill much of Sherman's industrial base, and its three hospitals and Austin College keep other roofs in constant service. Work is sequenced by section so operations continue below.

Foot traffic is a quiet cause of seam damage, so we note service paths to rooftop units and add walkway pads where traffic crosses laps. Damage to the sheet itself belongs to membrane puncture repair, and the two are often found together. The owner receives a roof plan with every repaired seam marked, so a later inspector can find and recheck each one.

The first visit is a walk, a probe and a scan. The crew marks each open seam and covers it with a temporary seal. Repairs follow in sections. For work across Sherman and nearby towns, the same record is kept for every roof: photos, readings, a seam map and a repair list. Tenants are told when work happens above them, and loud steps are scheduled in advance.

A plant at Progress Park or a logistics site near Denison may run on shifts, so access is agreed with the facility manager before the first day. We ask who holds the roof key, where material can be staged and which rooms sit under the work. Open seams are never left uncovered at the end of a shift. If weather turns, the crew seals the area, and the next visit picks up from the marked plan. At the close, the owner receives the seam map, the photos and a note on any lap that should be rechecked after the next hard freeze or storm.

Can one open seam be repaired alone?

Yes, if the surrounding seams test tight and the insulation is dry. We probe the neighbors first.

How do you know a weld is good?

We probe the edge along its full length and look for an even bead. Any gap is reworked.

Why do seams open in winter?

Cold shrinks the sheet, and the seam takes the pull. Old or weak welds fail first.

When is replacement better than repair?

When seams open in a pattern, insulation is wet across a wide area, or repairs have repeated in the same place.

What records should I keep?

Keep the seam map, photos, moisture readings and repair list with the building file.