Think about what lands on a roof over a food plant: fat from the kitchen exhaust, wash-down vapor, oil mist from a compressor, condensate carrying all of it toward the drain. An ordinary single-ply sheet on a quiet office roof would swell and stiffen under that load and open at the seams. KEE is the PVC-alloy membrane built for the opposite conditions, and a property manager with a processing, cold-storage or lab roof should ask whether it belongs in the estimate before choosing any sheet. The first move is a flat-roof walk of the exhaust points and the drains, since the exposure is written there.
We install, repair and replace KEE on low-slope roofs in the Bronx, NY, and we price it beside plain PVC so the difference is visible.
What Sets KEE Apart
KEE is a PVC-based membrane in which the softener is held in by a ketone ethylene ester polymer instead of being free to leach out. The sheet stays supple for years and its seams are welded with hot air, which yields a continuous membrane that tolerates animal fats, oils, many chemicals and the acidic ponded water of a dirty roof. Because the membrane is welded and not glued, each seam can be probed and tested before the crew leaves the roof, which is how a bad weld is found before the next rain. Drains, curbs and penetrations get preformed corners and boots in the same material, so the detail work never becomes the weak link.
KEE costs more than plain PVC and far more than TPO or EPDM, so a super should not expect it on every roof. The case for it is steady exposure: when a failed sheet would need replacing in a few years, the extra cost of the better sheet pays for itself. Both numbers sit side by side in the proposal and the owner picks.
Where It Fits in the Bronx
The Hunts Point peninsula is the borough's food and industrial center. More than 800 industrial businesses employ over 25,000 workers there, the Food Distribution Center covers 329 acres, and the Cooperative Market and the produce market are among the large refrigerated and warehouse buildings. A roof over cooking, processing or wash-down activity in that setting is the case KEE exists for, and a roof over dry storage is not. The walk sorts one from the other. A Special Hunts Point District, created in 2004 to encourage food distribution growth while protecting nearby housing, points toward industrial use staying put.
The railroad side of the borough raises a different question. Harlem River Yards in Port Morris covers 96 acres of waterfront, and its 28 acre intermodal rail facility sends diesel residue and yard grime onto nearby roofs. Before the full order, we test how a sample reacts to those deposits.
The Four Contaminated Zones
On a food or industrial roof the damage clusters in the same places. The exhaust area, where grease and condensate drip onto the sheet. The drain and sump, where contaminated water collects and sits. Any point where old coating or sealant touches the new sheet. And rooftop equipment that leaks oil, refrigerant or wash water.
Snow adds a fifth. Central Park records about 29.8 inches of snow a year, and melt that carries road salt and oil into a drain adds to the load on the sheet at the worst spot on the roof. We map the four zones and the drain paths on a sketch, give each exhaust unit a number and tie the repair list to that numbering. Operators who service equipment daily get walk pads along their route, since a worn footpath through a grease zone spreads residue across the whole roof.
KEE, PVC or TPO
Plain PVC copes with ordinary restaurant grease and light chemical contact, so over a kitchen it is usually enough. TPO suits a clean roof with no chemical load. KEE earns its price when fats and oils arrive heavily and constantly, as over rendering, processing or cooking at volume, or when an earlier sheet failed young from exposure. Where the exposure turns out to be mild, the proposal prices PVC or TPO instead, because a premium sheet on a roof that does not need it wastes money.
A cold-storage roof adds a separate problem. A cold interior pulls vapor upward, so the vapor retarder and the insulation joints matter as much as the sheet. Poor vapor design wets the insulation from below and the membrane takes the blame. Either sheet weighs little once rolled, so a few crane picks lift it to the roof and the staging footprint stays small enough to leave a dock lane open.
Working Around Live Operations
Food distribution does not close for a roof. Trucks run, coolers stay on and loading areas must stay clear, so hoisting and staging are scheduled away from dock hours, air intakes are covered while seams are welded, and roof traffic stays off any area above product handling. On a large roof, only one section is open at a time.
Hunts Point Avenue is the peninsula's main street and the Bruckner Expressway borders its western and northern edges, which shapes truck routes and delivery windows. We set those windows with the building manager, so a Hunts Point job runs on the facility's clock. No hot work happens near product handling, every open edge gets fall protection, and clean boots keep exhaust-area grease from being walked onto new membrane.
Sampling, Warranty and Closeout
Before choosing the sheet we cut a hand-sized sample from the existing roof, once near an exhaust unit and once near a drain, and look at how each aged, since a swollen or stiffened membrane shows what the exposure is doing and how fast. Manufacturers set terms on chemical exposure, and some limit coverage when fats or oils pass a certain level, so the terms get read first. A roof condition report records the roof as found, and a yearly commercial roof inspection catches contamination before it works into the seams.
Closeout includes the seam map, the sample results and a cleaning schedule for the drains and exhaust zones. The Department of Buildings publishes the 2022 NYC Construction Codes. Check filings with them.
Commercial Roofing Questions
How do I know a roof needs KEE rather than PVC?
The exhaust tells the story. A restaurant fan that drips now and then is a PVC job, while constant fat, oil or chemicals from processing, wash-down or industrial exhaust point to KEE, and the walk confirms it.
Does KEE cost much more than standard PVC?
Per square foot, yes, since the polymer is a premium material. Set the cost of replacing a failed sheet beside the added price of the better one, and the proposal shows both figures.
Can KEE go over an existing roof?
Yes, if the insulation is dry and a separator sheet shields the new KEE from old asphalt or foam it cannot touch. We scan for moisture first and cut out any wet sections before laying new membrane.
What happens when grease reaches a KEE sheet?
The sheet resists the damage, but cleaning still pays. Washing the drain areas and exhaust zones on a schedule keeps residue from clogging drains, and inspections confirm the membrane is holding.
How are KEE seams repaired?
By hot-air welding, as with PVC, after the surface is washed, because oily sheet refuses a weld. A test weld goes first, and damaged membrane is cut out and replaced.
Send the Exhaust List and the Roof Age
Tell us the building use, what the exhaust puts onto the roof and when the last leak showed. We will walk the flat roof and write up whether KEE or a lower-cost sheet fits.
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