Rooftop Grease Containment for Hamilton Commercial Kitchens
Rooftop grease containment is the practice of capturing the grease a commercial kitchen exhaust fan discharges at roof level, so it does not spread across the roof surface, run down a parapet, or reach a storm drain. Every Type 1 exhaust system ends at a fan on the roof, and everything the cleaning misses upstream arrives there. Hamilton Hood Cleaning cleans the fan, the curb, and the roof area around the discharge point on the same visit as the hood, then documents the condition with before-and-after photographs and a signed certificate referencing the NFPA 96 standard. Single-hood kitchens start from $385 per visit.
Why grease on the roof is the building owner problem, not the kitchen problem
Grease discharged at the fan lands on roofing the tenant does not own, which is why a rooftop grease question usually arrives from a landlord or a property manager rather than from a chef.
The exhaust fan sits on a curb, and grease-laden vapour leaves through it. Some of that vapour condenses at the fan housing and drains back down the curb. The rest settles on the roof surface downwind of the discharge. On a busy fry or char line the affected area grows outward season by season until the roof around the curb reads dark and tacky, and by then the grease has usually already found a low point.
Two things then happen that cost money. Grease attacks the roof covering, and grease travels. On the covering side, a single-ply membrane and the adhesives and seam welds holding it together are not specified to sit under a petroleum-adjacent contaminant for years. On the travel side, a roof drains somewhere, and what the roof drains carries goes into the building storm system.
What rooftop grease does to a TPO or EPDM membrane and to the roof warranty
Grease softens and degrades single-ply membrane materials over time, and most roofing warranties exclude damage caused by a contaminant the building allowed to sit on the roof.
Flat commercial roofs across Hamilton are mostly single-ply. TPO is the light-coloured thermoplastic sheet welded at the seams. EPDM is the black rubber sheet bonded at the laps. Both are engineered for weather, foot traffic during service work, and ultraviolet exposure. Neither is engineered as a grease tray.
Grease that runs off the curb and down a parapet or an exterior wall also stains masonry and stucco visibly, and on a converted storefront that stain lands on the street elevation.
Sustained contact matters more than a spill. Standing grease keeps a surface permanently wetted, holds grit against it, and works into seams and flashing details where the sheet is bonded rather than continuous. Those details are where a roof fails first under any condition, and grease gives them a head start.
The warranty consequence is the part that surprises owners. A roofing warranty covers the roof performing as installed. It does not usually cover the roof being exposed to something outside its specification, and a documented pattern of exhaust grease around a fan curb is a straightforward exclusion for a manufacturer to point at. The practical result is a roof that fails early with no coverage behind it, on a building where the operator downstairs assumed hood cleaning was the whole of the obligation.
Grease reaching a storm drain is a separate exposure
Roof drainage carries whatever is on the roof, so grease around a fan curb eventually reaches the building storm system rather than the sanitary system where kitchen waste belongs.
Kitchen grease is meant to leave a building through the sanitary side, controlled and interceptable. A roof drain is sized and permitted to move rain, so anything riding along with the rain has skipped every control the building has.
Rain events are what make this visible. A dry stretch lets grease build up around the discharge zone, then the first heavy rain moves the accumulation to the low point and into the drain in one go. That is why the discovery is so often a slug of grease at a downstream point rather than a gradual complaint.
For a multi-tenant building the exposure compounds. A shared roof drain serves everyone, and the source of what shows up in it has to be traced. A building owner who can produce dated photographs of a clean fan curb after each service visit is in a very different position from one who cannot. That is one of the reasons every visit here ends with the photo record, described in more detail on the NFPA 96 compliance guide.
Rooftop grease containment options compared
Containment approaches differ mainly in how much grease they hold, how often the media has to be changed, and whether anyone actually maintains them once fitted.
| Approach | What it actually does | Media change | Where it suits a Hamilton roof |
|---|---|---|---|
| Nothing fitted | Grease discharges straight onto the membrane and spreads with weather and slope. The cheapest option until the roof is assessed. | None, and the roof absorbs the cost instead. | Only defensible on a very light-volume kitchen with a gravel or ballasted roof and a documented cleaning interval. |
| Absorbent filter box at the curb | A shallow tray or box holding absorbent media catches drainage from the fan housing before it reaches the roof surface. | Media saturates and needs changing on a set interval. Once saturated it stops working entirely. | The common fit on a converted James Street North or King William storefront where the riser is short and the roof is tight to the fan. |
| Catch basin or grease box | A larger reservoir collects liquid grease rather than absorbing it, so volume can be seen and drawn off. | Emptied rather than replaced, but it overflows if nobody checks it. | Heavy fry and char lines, and Stoney Creek or Ancaster business park kitchens where the fan runs long hours. |
| Full containment tray under the fan | A tray sized to the curb footprint holds media across the whole discharge area, not just the drain point. | Highest media consumption, and the change has to be logged to be worth anything. | New membrane roofs still under warranty, and downtown multi-tenant buildings with a shared roof drain. |
The failure mode is the same for all three fitted options: the containment gets installed once and then forgotten. Saturated media is not containment. It is a soaked object sitting on the roof that everyone believes is solving the problem. Whatever is fitted on your building, the media interval has to be tied to the cleaning schedule so that one visit handles both.
What a rooftop grease visit covers in a Hamilton kitchen
A rooftop visit degreases the fan housing and blower wheel, cleans the curb and the roof area immediately around the discharge, checks any containment fitted, and reports the condition in writing.
Access sets the shape of the visit before anything else. On Concession Street, downtown Dundas, and Ancaster village the roof-mounted fan is reached by ladder rather than by an interior stair, which changes both the safety setup and how long the work takes. On downtown towers and larger Stoney Creek buildings there is usually proper roof access, and the constraint moves to permission, escort, and after-hours entry instead.
Work is scheduled overnight and between service hours so the kitchen does not lose a shift. Grease removed at the fan is collected and taken away rather than washed across the roof.
Every visit ends with the same two documents: before-and-after photographs of every cleaned surface, and a signed health and safety certificate referencing the NFPA 96 standard. For a property manager those photographs are the useful part, because they are the dated evidence that the fan curb was clean on a known date. Proof of WSIB coverage and liability insurance is supplied before anyone goes on the roof.
Pricing starts from $385 per visit for a single-hood kitchen and from $725 for a multi-hood kitchen of two to four canopies. Campus, hospital, contract-catered, and multi-tenant buildings are quoted after a free walk-through. The full breakdown is on the exhaust cleaning cost guide, and the work upstream of the roof is covered under kitchen exhaust cleaning.
Best rooftop grease containment in Hamilton for a landlord or property manager
The right containment for a managed building is the one whose maintenance is scheduled and documented, because an unmaintained system transfers the risk back to the roof.
If you hold the roof and the tenant holds the kitchen, three things are worth writing into how the site is run. Tie the containment media change to the hood cleaning visit so a single contractor is accountable for both. Require the photo record to include the fan curb and the roof area, not only the canopy. And keep the records where a roofing manufacturer or an insurer can be shown them, which usually means the property file rather than the tenant's back office.
Call 289-796-0840 or use the contact page to book a walk-through. Coverage across Hamilton and the surrounding communities is listed on the areas served page.
Rooftop grease containment: frequently asked questions
What building owners and property managers ask about grease at roof level.
Does hood cleaning include the roof and the fan?
Hamilton Hood Cleaning includes the rooftop exhaust fan in the cleaning scope, along with the curb and the roof area immediately around the discharge point. That matters because a cleaning visit that stops at the canopy leaves the part of the system that is discharging onto the roof untouched, and it also leaves the compliance question open, since the NFPA 96 grease limit applies to any surface in the exhaust path.
Can rooftop grease void a roof warranty?
Roofing warranties generally cover the roof performing as installed and exclude damage from contaminants the roof was never specified to carry. Exhaust grease sitting on a TPO or EPDM membrane is a visible, documentable condition, which makes it a straightforward exclusion for a manufacturer to point at. The defence is a maintained containment system plus dated photographs showing the fan curb clean on a known schedule.
How often does containment media need changing?
Containment media has to be changed before it saturates, and how fast that happens depends on the cooking volume rather than on the calendar. A heavy fry or char line loads media far faster than a low-volume kitchen. The practical approach is to tie the media change to the cleaning visit so one contractor handles both, then adjust the interval based on what the media looks like at each visit.
Who pays for rooftop grease cleanup, the tenant or the landlord?
That depends entirely on the lease, and the split is a common source of disputes because the exhaust system usually sits with the tenant while the roof sits with the landlord. Grease crosses that line. The cleanest arrangement is for the rooftop portion to be part of the same scheduled exhaust cleaning contract, so it gets done and photographed on a known interval instead of being argued about after a roof inspection.
Is a rooftop visit disruptive to service?
No. Rooftop work is scheduled overnight or between service hours so the kitchen does not lose a shift. The main scheduling constraint in Hamilton is access rather than the work itself: a ladder-only roof on a Concession Street or Dundas strip needs a different setup than a downtown building with interior roof access and after-hours entry rules.