Grease eats roofs, and a restaurant produces it every hour it is open. The exhaust hood sends a fine film of fat up through the fan and onto the membrane around it, and over a few seasons that film softens many common roofing materials, loosens seams and lets water in. So the first question on a restaurant roof is not how much snow it carries, though the City of Coeur d'Alene, ID design sheet does list a 60 psf ground snow load. It is what the exhaust fans do to the membrane next to them.
We bid a restaurant roof around the kitchen, not around the building. The membrane choice, the curb details, the fire rules and the service hours all start from the exhaust. Each one gets a line, and the owner or the franchisee can see what protects the roof and what finishes it.
The Call: Match the Membrane to the Exhaust
For a restaurant, PVC is the first system we price. It resists fats and oils better than most alternatives, and its welded seams hold up in the zone around the fans. In some cases a liquid-applied coating or a grease-rated cap sheet protects a limited area. EPDM and some modified bitumen products soften when grease sits on them, and we avoid them near the exhaust unless the layout keeps the fans well away.
Grease containment is the second half of the call. A fan with no containment dumps its load onto the roof, and the best membrane in the world will eventually show it. We look at the hood exhaust, the grease cups and the cleaning schedule, and we price a containment tray or a splash guard where the existing arrangement leaks. The roof stays cleaner and the cleaning crew has an easier job. We also check where the hood cleaning contractor sets down buckets and hoses, because rinse water carrying grease across a membrane does as much harm as the fan itself. A rubber mat and a drain path at the cleaning point fix that for the price of a mat.
What It Costs: Curbs, Fans and Fire Rules
The cost of a restaurant roof comes from the small area around the equipment, not the field. Exhaust fans, make-up air units, walk-in cooler condensers and the vent stack for the dish room all sit on curbs. Each curb is a flashing detail. Replacing the roof often means lifting and resetting the fan, which needs the kitchen to shut down for a short time.
Fire safety adds to the list. Torch-applied systems near an exhaust duct are a hazard, and we avoid them. Where hot work cannot be avoided, a fire watch and permit become line items. Insulation under the membrane is usually a code requirement, and the added depth raises the curbs. A pad-site restaurant with a small roof still carries the full set of curbs, so its price per square can look high next to a bigger building, and the owner should read the curb lines before reading the total. The crane or lift that sets the fans is a fixed cost too, and a small roof does not make it smaller.
Where It Fails First: Fan Curbs, Grease Zones and Patios
Restaurants fail at the fans. The membrane around a fan curb softens under grease, the flashing opens, and water runs into the kitchen ceiling. Grease also coats walking routes, so techs slip and tear the sheet. Patios, covered entries and canopies add slopes where snow slides and freezes, and they have their own flashing against the main wall.
Tourism has been the main driver of the Coeur d'Alene economy since the 1940s, and a kitchen in a visitor market runs hardest in the summer months. A pad-site restaurant near the Village at Riverstone works that same busy season. A roof that fails on a Friday in July costs the restaurant more than the repair, so we plan the walk-through for the quiet weeks. In the spring, before the season builds, is when the membrane around each fan should be checked, cleaned and, where needed, patched. A roof that gets through May in good shape usually gets through August, and that holds for a pad-site kitchen in Hayden or Post Falls as much as one near I-90 in Coeur d'Alene, because the fans run on the same schedule wherever the building stands.
What the Code Sheet Says: Snow, Wind and Energy
For a small restaurant building the city's 60 psf snow design drives the drift check at parapets and canopies, and the 115 mph wind speed drives the fan and screen supports. The statewide 2018 energy code also sets the insulation depth that raises the curbs.
Snow is more than a load on a restaurant roof. A canopy over a patio or an entry has people under it, and wet snow is heavy. A slab that slides from the main roof lands on the dining area. Snow guards or a retention layout above patios and entries belong in the scope for any building where customers wait or sit under the eave.
Alternates: What the Operator Can Choose
Restaurant owners and franchisees get a simple list:
- Grease containment trays at every exhaust fan
- Walkway pads on the route from the hatch to each fan
- Snow guards over entries and patios
- A grease-resistant coating on the existing membrane at the exhaust zone
- A quarterly roof check tied to the hood cleaning visit
- Night or early-morning work to avoid service hours
The containment trays and the walkway pads protect the new roof from the two things that wear it fastest. A franchisee who signs a lease with a fixed term should weigh the pads and trays against the years left on it, since both pay back over the life of the membrane and a short lease may not cover that. The quarterly check costs little and fits with the hood cleaning schedule the kitchen already keeps.
Closeout: A Roof Plan the Kitchen Crew Can Use
The operator receives a roof plan that shows each fan, each curb and the walking route to them. The hood cleaning crew uses the same plan, and a stain on the membrane gets spotted quickly. A coating restoration can extend a roof that is sound but stained, and a repair handles a single leaking curb. A pad-site restaurant beside a plaza shares details with a shopping center, and its exhaust problem is the one a grocery store has. A chain can run all its locations through a multi-site roof program. PVC is the first choice around exhaust, and restaurants in downtown Coeur d'Alene and Riverstone follow the same steps.
Commercial Roofing Questions
Which roofing materials fail under kitchen grease?
Some EPDM and modified bitumen products soften when fat sits on them. PVC resists it much better, and a coating can protect a small zone.
Does the kitchen have to shut down for a reroof?
Only briefly, when a fan is lifted and reset. The rest of the work runs around service hours or in the early morning.
Why is torch work avoided on restaurants?
Open flame near duct work and grease deposits is a fire risk. We use welded or adhered systems and add a fire watch if heat is unavoidable.
How does a grease tray help the roof?
It catches what the fan throws so it does not reach the sheet. Cleaning the tray is faster than scrubbing the membrane.
Should a patio roof have snow guards?
If customers sit or wait under the eave, yes. A sliding slab is a danger and a guard is a small line in the bid.