Welds, Boots and Matching Details
A grease-resistant field sheet does little good if the flashing around it is a weaker material. We use KEE flashing and pre-molded pipe boots in the exposed zone, welded to the field sheet with the same rounded-corner cover strips we use on every thermoplastic roof, and we probe the seams along their full length. Mastic and caulk are not substitutes for a weld, and where an old repair has been smeared in place we cut it out and replace it with a detail that can be tested.
Some older roofs are built on asphalt or coal tar, and PVC-based sheets cannot touch those materials without a separation layer, because plasticizer and bitumen migrate into each other and ruin both. A KEE roof over an existing bituminous roof needs that barrier, and we confirm it in the scope. When the existing roof is wet, the right answer is often to remove it, a point we weigh against a possible roof recover after a moisture survey.
Breweries, Labs and Food Plants
The Lincoln Avenue corridor in northwest Pasadena has a microbrewery and a micro distillery among its cafes, and the Walnut district hosts the Pasadena Bioscience Collaborative for biotech startups. A brewery, a distillery or a biotech laboratory can put warm, humid, sometimes chemical exhaust on a roof, and none of it is the grease of a lunch counter. A KEE sheet is worth the question wherever vapor, solvents or process exhaust leave a building, and we ask what is being vented before we recommend any membrane.
In Vernon, about 46,000 workers are employed daily, mainly in food manufacturing, metalworking, and glass and plastic production, and a food plant puts fat, steam and cleaning chemicals on its roof. A food employer such as Ready Pac Foods in Irwindale faces the same question, as does any manufacturing plant. Those buildings need a membrane chosen for what runs through the roof, not only for what falls on it from the sky.
Curbs, Splash Guards and Walkway Pads
Details around the fan do as much work as the membrane. A splash guard on the curb stops fat from running down the side, a drip tray catches the heavier discharge, and a walkway pad gives the hood cleaning crew a place to stand that is not the sheet. We ask the exhaust cleaning contractor to use containment so wash water and fat do not flow across the roof, and we put the request in writing for the property manager to pass along.
Insulation and a cover board go under the sheet, with PVC and TPO considered for the other parts of the roof where the exposure is lighter. Mixing sheets on one building is legitimate when each one suits its zone, though the transition between them has to be a welded detail with a sealed edge, not a lap of two incompatible materials.
Reflectance, Heat and Fire Zones
A white KEE sheet can meet the aged reflectance and emittance the 2025 California Energy Code asks of low-slope roofs, but the figure to read is the aged one on the product listing. Pasadena's recorded high of 113 F in June puts hard thermal stress on a dark roof, and reflectance lowers the surface temperature and the cooling load on the tenants below. We check the listing, write the scope to it, and plan for periodic washing so grease and dirt do not quietly lower the number.
Foothill buildings face a second question. In Very High zones the Class A rating belongs to the whole assembly, so insulation, cover board and sheet are specified together. The upper reaches of Hastings Ranch and the Arroyo Seco lie in mapped zones, and the roofs there have to handle both ember exposure and, in kitchens or labs, whatever the building vents.
Commercial Roofing Questions
How do I know whether my building needs KEE instead of ordinary PVC?
Look at what comes out of the roof. Kitchen exhaust, rendering and fryer vents, process steam, solvent fumes and brewery vapor all point toward KEE, while a quiet office roof with only air handlers rarely needs it. We walk the roof, trace each exhaust to its source and write the membrane choice to the worst exposure the building produces.
Can KEE go over an existing roof without a tear-off?
Sometimes, if the old roof is dry and sound and a separation layer keeps the new sheet from touching asphalt or coal tar. An infrared survey and core cuts tell us whether the insulation beneath is dry. If it is wet, a recover simply buries the problem, and the cleaner path is to remove the old roof.
Will a manufacturer still stand behind a roof that takes grease from a kitchen?
Terms differ from one product to another, and some limit coverage for grease unless the membrane is rated for it. We read the terms for the specific sheet before specifying it and put the exposure in writing, so the owner knows what the paperwork says before the work begins.
What happens when a hood cleaning crew dumps grease on the roof?
KEE tolerates fat far better than a standard sheet, but a pooled spill still stains the surface, holds dirt and lowers reflectance. We recommend containment, a clean-up routine after each service and a periodic wash. A visit after a bad spill is cheaper than finding the stain on a ceiling a few weeks later.
How do you repair a KEE roof that already has old patches on it?
We start by identifying what each patch is made of, because mastic, tape and mismatched membrane all behave differently. Failed patches are cut out and replaced with welded KEE strips, with rounded corners and a probe test along the edge. Where patches are numerous, we map them on a roof plan so the owner can see how much of the sheet has been compromised.
