1. Article Body
A restaurant roof is specified around one thing: what comes out of the kitchen exhaust. Get that wrong and the membrane fails years early no matter how well it was installed.
Grease is the governing condition
Kitchen exhaust carries vaporized animal fat and cooking oil. It condenses on the roof surface downwind of the hood fan and stays there.
Grease attacks some roofing materials and not others. This is the reason PVC membrane is specified on restaurants far more often than TPO, which is otherwise a close substitute. PVC resists fats and oils meaningfully better.
If someone proposes a membrane for a restaurant without asking about the kitchen exhaust, they are not specifying, they are quoting.
The grease containment question
A hood fan without proper containment discharges directly onto the roof. Containment systems capture it into a replaceable absorbent medium.
Containment is a maintenance item that needs servicing on a schedule tied to cooking volume, not to the calendar. A high volume fryer operation saturates a containment pad far faster than a bakery.
Where containment is absent or neglected, the membrane around the fan degrades first and the damage radiates outward with the prevailing wind.
Everything else on the roof
Restaurants carry heavy rooftop loads relative to their size. Makeup air units, multiple condensers for refrigeration and comfort cooling, walk in cooler and freezer condensing units, exhaust fans and sometimes a grease duct riser.
Every one is a curb, a penetration or a support, and every one has a service contractor who will access the roof.
Condensate lines from all of that equipment discharge somewhere. On a shallow slope, a continuously wet area is a failure waiting to happen.
The access problem
Restaurant roofs get walked constantly. Refrigeration technicians, hood cleaners, HVAC service, fire suppression inspections for the hood system.
Hood cleaning crews in particular work near the fan with hoses and chemicals. Without walkway pads and a controlled access process, the roof takes damage from the people maintaining the equipment on it.
Operating hours
Most restaurants cannot close, and the ones that can lose revenue doing it. Reroofing happens overnight, in phases, or during limited dayparts, and that constrains the schedule and the price.
Work above a kitchen also raises food safety questions, which means the health authority and the franchise operator may both have a view.
What to establish first
Cooking type and volume. Whether grease containment exists and is serviced. Membrane type currently installed. Rooftop equipment inventory. Who accesses the roof and how often.
Those five explain the condition of almost any restaurant roof.
