A welded seam on a thermoplastic roof is only as good as the weld, and the only way to know is to test it. Sika Sarnafil is a manufacturer of thermoplastic single-ply membranes, best known for PVC-based sheets that are joined by hot-air welding, and owners of commercial buildings in West Jordan, UT will meet that type of roof on a range of building uses. We install, repair and maintain thermoplastic systems of this kind, and the first visit to such a roof is spent on its seams, its flashing details and the drains that carry snow melt away.
What failed first: weld lines and flashing
Thermoplastic sheets are welded at their overlaps, so the weld lines are the first thing we probe. A good weld shows a consistent bead at the edge of the seam. A weak one may have a gap, a skip or a fish-mouth where the sheet has lifted. Flashing is the next suspect. Wall bases, curbs and pipe penetrations are detailed with welded or adhesive-applied pieces, and movement at those transitions can break the bond.
We run a probe along seams, look at weld edges, photograph defects and note them on the sketch. We also look for surface wear: crazing, discoloration and thin spots near rooftop equipment where service traffic has worn the membrane. These signs tell us where the sheet has been stressed.
Welds age in a particular way. Heat, ultraviolet light and movement slowly stiffen a thermoplastic sheet, and a stiffer sheet cracks where it was once flexible, usually at corners and folds. We press on suspect areas to feel for brittleness and note any crazing. A sheet that has stiffened across much of the roof is a candidate for planning, even if every seam still holds today.
Roof-walk notes: exhaust, grease and compatibility
Thermoplastic membranes are often chosen where roofs see exhaust or grease, because the material resists many fats and oils better than some alternatives. That does not make the roof indifferent to them. Repair materials and coatings have to be compatible with the sheet, and the wrong one can cause blisters, softening or poor adhesion.
We identify the membrane type before proposing anything, and we check the area around kitchen exhaust, mechanical vents and drains for staining or surface change. Where a rooftop fan discharges onto the roof, a protective pad or a different fan curb can save the membrane. Material compatibility goes in the written scope, and we follow the manufacturer's published guidance where we know it.
Drains and sumps deserve the same compatibility check. Cleaning products, sealants and primers used at drain bowls can attack a sheet if they are the wrong type. We name the materials in the scope, apply them only where they belong and photograph the finished detail. A drain that was resealed with an unknown compound is a question mark for the next visit, and the file should have no question marks.
Drainage and melt: ice, edges and weld lines
Winter loading in the valley comes from snow and repeated freeze-thaw periods, and Salt Lake City airport normals give the regional pattern without recording conditions at each West Jordan roof. Elevation and exposure vary. What matters on the roof is the sequence after melt: drains clear or blocked, low spots drained or standing, edges tight or lifted.
Cold weather also changes repair practice. Thermoplastic sheets can be welded only within certain temperature ranges and on dry, clean surfaces, so winter repairs are usually temporary and permanent welding waits for a warmer window. We note that in the scope and mark temporary work on the sketch so the permanent fix addresses the right spot.
Whatever a building's use, rooftop equipment and traffic differ from one to the next, and the same habit applies: after melt, walk the roof, follow the water and write down what you find. A building with heavy rooftop service traffic needs walkway pads more than one without, and a building with rooftop exhaust needs the chemical check described above.
Repair boundary: patch, restore or replace
A repair on a thermoplastic roof means cleaning the area, welding or bonding a compatible patch and testing the result. A roof with sound seams and worn surface might take a coating, though not every coating works on every sheet. Wet insulation or widespread seam failure points toward replacement, which might mean new PVC roofing or another system, depending on the building.
What drives price here is roof area, tear-off, insulation, penetration count and access. Energy provisions in Utah's 2024 codes, effective since July 1, 2026 and amended at state and local level, get reviewed whenever a replacement exposes the insulation. The scope states the proposed insulation values.
Edges and perimeters finish the picture. Thermoplastic sheets are often terminated at metal flashings that are bonded or welded to the sheet, and ice or wind can lift them. We press-test edge metal, check fasteners and sealant and look for gaps at joints in the metal. Securing an edge is a small repair compared with the damage from a section of membrane peeled back by wind.
Warranty terms and records
Manufacturer warranties may limit who repairs the system, require notice before work and set upkeep duties for the owner. Each warranty condition is checked against the roof, and the scope is written so that it honors them. The roof warranty management record keeps the document, notices, dated photographs and repair details together, so a question years from now has an answer on paper.
Where a roof has been altered after installation, the file should show who did what. A new vent, a relocated unit or a patched puncture all leave a mark on the system, and an uncertain history makes warranty conversations harder. We record alterations as we find them and ask owners what they know. Even a partial record is better than none, and it improves each time the roof is walked.
Next check: what to send
Give us the address, whatever roof documents exist and where water appears, along with how the roof is reached and what runs under it. The walk probes the welds and reports what the sheet and flashing need. A second building with a Duro-Last or Soprema roof gets the same walk, and a property in West Jordan is scheduled around tenant hours. If the roof is scheduled for replacement within a few years, tell us. We can time the repair scope to bridge the gap with the least waste, and we can include the replacement in a roof capital plan so the budget and the calendar line up.
Commercial Roofing Questions
How do you test a welded seam?
We run a probe along the seam edge to find gaps or unwelded sections, then mark and photograph any we find. Suspect spots are cleaned and re-welded.
Can any patch material be used on a thermoplastic roof?
No. The patch must be compatible with the sheet or it can blister or fail to bond. We identify the membrane first.
Can seams be welded in winter?
Only within temperature and moisture limits. Winter repairs are usually temporary, and permanent welding waits for a warmer, dry day.
Does exhaust damage a PVC roof?
Many fats and oils are tolerated better than on other sheets, but fan placement, pads and cleaning still matter. We check around every discharge.
Who handles warranty questions?
Warranty terms belong to the owner and the manufacturer. We install, repair and keep the records, and we read the terms with the owner before any repair starts.
Share where water appears and how access works
Send the address, roof papers and leak history. We will walk the roof, test the seams and report what the system needs.