Grease on the membrane near a kitchen exhaust tells us more about a thermoplastic roof than the date on its warranty. Sika Sarnafil is best known for reinforced thermoplastic sheet, and that sheet is usually chosen for roofs that see heat, chemicals and foot traffic. In Springfield, MA, the same sheet then faces freeze, thaw and snow load. A repair plan has to account for all of it, so we examine the contamination, the welds, the details and the drains before deciding whether a patch, a section replacement or a recover will serve the owner best.
Check what the sheet has been touching
Walk the roof and look for stains and softened surface near exhaust fans, kitchen vents, process stacks and mechanical units. Oils and some cleaning chemicals can attack a thermoplastic membrane over time, and the damage may appear as discoloration, crazing or a tacky feel. We note each affected area, take photographs and record whether the surface can be cleaned and welded or must be replaced. A weld made on a contaminated surface can pass a glance and fail within a season, so cleaning comes before any repair.
Walk pads and protection sheets under exhaust discharge are a low-cost fix that often prevents the next round of damage.
Cleaning method matters too. A solvent that suits one family can harm another, so we test a small patch of the cleaner before treating a larger area. The test result and the product used go on the closeout sheet, so the next crew does not repeat a mistake or undo a fix.
Where cleaning cannot restore the surface, the damaged sheet is cut out to clean material and a patch is welded over the opening with generous overlap on every side.
Probe the welds and the corners
A PVC roof is welded with hot air, and a good weld leaves a continuous bead along the lap. We run a blunt probe along every seam in the area under review and mark any spot where the edge lifts. Corners and T-joints, where three layers meet, get extra time, since the weld there is the hardest to make well. Sheets in this family also come in KEE-modified formulations, a blend meant to resist plasticizer loss and chemical exposure, and a repair has to use the cleaner and patch that suit whichever one is on the roof.
The reinforcement inside the sheet is a second thing to check. If a cut or abrasion has exposed the scrim, water can wick along it, so a puncture that looks small on the surface may need a larger patch than the visible damage suggests. We cut back to clean, undamaged sheet before welding, and we round the corners of every patch so they do not catch and lift.
Flashings, curbs and odd shapes
Where a prefabricated corner or a standard boot cannot fit, a liquid-applied flashing resin or a custom-welded piece fills the gap. These details fail more often than the field of the roof. We check each flashing for bond at the top edge, for cracking at inside corners and for movement at the base. Equipment curbs and supports get a separate look, because service crews walk and drag tools across them, and a puncture near a curb is a frequent finding.
On a busy rooftop, we also look at the route that maintenance staff take to reach their equipment. A worn path across a membrane tells us where walk pads belong. Adding them is a small cost compared with replacing a punctured section a year later.
Healthcare and institutional roofs
The Medical District study inventoried about 315 medical and health services establishments in 2011, with close to 10,000 workers, mostly in the North End and bisected by I-91. Buildings with heavy mechanical systems make exhaust discharge, intake locations and air handling units part of every work plan. In the Medical District and around the Baystate South Campus in Six Corners, we plan around intakes, entrances and quiet hours, and we protect the area below the work zone before any tear-off.
Noise and dust are the other concerns. Tear-off is loud, and debris must be contained and lowered by chute or hoist, not dropped. A daily closeout walk with facilities staff confirms that the section is dry and that walkways below are clear before the crew leaves.
Ice, cold welds and weather windows
Hot-air welding needs a dry sheet and a workable temperature, so a cold, wet week stops bonded repairs. Under the state's 2023 ResilientMass plan, heavy snow and ice loading on roofs is one of the harms expected from severe winter storms. We clear drains before the first heavy freeze, check for low spots that hold ice, and install temporary protection if a repair has to wait for the weather. Finished welds are tested again once the sheet is warm and flat.
Snow itself is a scheduling factor. A roof under a foot of snow cannot be inspected or repaired, and removing the snow without cutting the sheet takes care. We plan inspections for the dry weeks of late spring and early fall when we can, and keep the winter calls for emergency protection and drain clearing.
Decision and turnover record
When contamination or age has damaged large areas, replacement of that section is a better capital choice than repeated welds. The turnover record lists the sheet, the contaminated zones, the repair limits, the photographs and the next inspection trigger. A building with sections from different makers, such as a Duro-Last addition next to a Sarnafil main roof, gets the junction drawn on the plan.
The record also names who holds the manufacturer paperwork, so a later claim does not stall on a missing letter. When a replacement is on the table, the written scope states the sheet to be used, and a thermoplastic system from Versico is one of the alternatives that can be priced on the same roof plan.
Permit review comes first on a section replacement. The Building Division applies the 780 CMR 10th Edition in Springfield, and the permit file should show the new assembly, the insulation and the attachment method. Gathering that documentation before material is ordered keeps the schedule from stalling at inspection time.
Commercial Roofing Questions
Can grease damage a Sika Sarnafil roof?
Yes, over time. Oils and some chemicals soften thermoplastic sheet near exhausts. We look at the surface in those areas, clean what can be cleaned and replace what cannot be saved by cleaning.
Is every weld on a thermoplastic roof tested?
In the repair area, yes. We probe each lap and mark failures on the sheet itself. A full-roof probe is part of an inspection scope whenever the owner wants one, and the results go into the report.
Can a patch be made in cold weather?
Sometimes. The sheet must be dry and clean, and the welder needs a workable temperature. If those are missing, we install temporary protection and complete the weld when conditions allow, usually within the next dry window.
What is the difference between PVC and KEE sheet?
KEE-modified sheet carries a blend meant to resist plasticizer loss and certain chemicals. We confirm which one is on the roof before we choose cleaners and patch materials, because the wrong pairing can fail at the seam.
Do hospitals need special roof access plans?
Yes. Air intakes, entrances and patient routes must stay protected. We agree on the work zone, the hours and the closeout steps with facilities staff before the crew starts, and we post them where the crew can read them.
