Rooftop Grease Containment in Markham
Rooftop grease containment is a fan-mounted collection system that catches the grease a kitchen exhaust fan discharges before it reaches the roof surface. Markham Hood Cleaning fits containment sized to the fan, replaces the absorbent media on a schedule, and photographs the roof around the curb so a tenant is not later billed for damage that was already there. Discharge is continuous, so containment is the only thing that turns a recurring liability into a fixed line item.
What discharge actually does to a roof
Not everything that goes up the duct stays inside the fan. An upblast exhaust fan throws air outward and downward around its housing, and the fraction of grease still airborne at that point lands on the roof beside the curb. On a fan without containment it forms a ring that spreads with the prevailing wind, then migrates further every time it rains.
The damage is chemical rather than cosmetic. Cooking oils plasticize modified bitumen and attack single-ply membranes, softening the sheet and breaking down seams. A greased seam holds water, water freezes, and a Markham winter does the rest. Roofs fail early around kitchen curbs far more often than anywhere else on the same building, and the tenant whose fan caused it is usually the one holding the repair clause.
There is a second cost that shows up sooner. Grease tracked across a roof gets walked into stairwells and elevators by every trade that goes up there, and it makes the roof genuinely dangerous to work on. Property managers in Markham's plazas and business parks increasingly write containment into leases for exactly that reason.
Containment vs cleaning the roof after the fact
Both cost money. Only one of them stops the problem recurring.
| Consideration | Fitted containment | Cleaning the roof afterwards |
|---|---|---|
| Where the grease ends up | In replaceable absorbent media inside a box. | On the membrane, until somebody removes it. |
| Effect on the membrane | Contact stops, so degradation stops. | Damage already done, and cleaning solvents can add to it. |
| Cost pattern | Known, scheduled, budgetable. | Unpredictable, and ends in a repair bill eventually. |
| Position at lease end | Documented from the day it was fitted. | Tenant argues about who caused what, without records. |
| Drain and gutter risk | Grease never reaches them. | Runoff carries it into roof drains and downpipes. |
Roof access usually needs the landlord's agreement. Markham Hood Cleaning writes the split into the quote so it is clear who approves what.
How containment is sized and serviced
A box that is too small overflows, and an overflowing box is worse than none at all.
Sizing starts with the fan, not the kitchen. The assessment records the fan model, the curb dimensions, the discharge pattern, and how much clearance there is around the housing for a technician to work. A rooftop unit sitting close to a parapet or crowded by other equipment needs a different profile from one standing alone in the middle of a flat roof.
Cooking volume then sets the service interval. A wok or fry line discharging continuously loads absorbent media far faster than a bakery line, and the interval is set from that rather than from a default. Media replacement is booked forward on the same schedule as the hood cleaning wherever possible, so one roof visit covers both and the fan is only opened once.
Servicing includes lifting the fan to check the housing and the wheel underneath, which is where a hinge kit earns its keep. A bolted-down fan takes long enough to open that it quietly gets skipped, and the containment box on top of it gets skipped with it. That is covered on the exhaust fan hinges page. Used media is removed from site as part of the visit rather than left in a bin on the roof.
How much does rooftop grease containment cost in Markham in 2026?
Markham Hood Cleaning quotes containment supply, fitting and scheduled media replacement after a free roof assessment, and it is usually fitted alongside a hood cleaning visit, which starts at $385 per visit.
The fitting is a one-time cost driven by the fan size and how awkward the roof access is. After that the recurring cost is media replacement, which is small and predictable. Set against a membrane repair around a kitchen curb, or a dispute at the end of a lease about who degraded the roof, the arithmetic is not close.
Multi-tenant buildings are quoted per fan, because in a plaza with several kitchens the fans discharge onto one shared roof and the property manager usually wants every unit fitted rather than one. Markham Hood Cleaning can quote the whole roof to the building and the interior work to each tenant separately.
Next step: call 289-806-9117 or request a written quote. Confirm who authorises roof access, because that is the only thing that usually delays this job.
Rooftop grease containment in Markham: frequently asked questions
Who pays for containment, the tenant or the landlord?
It varies by lease and it is worth reading before the conversation. The grease comes from the tenant's kitchen, so tenants are commonly asked to fit and service it, while the roof itself belongs to the building. Many Markham leases now require containment outright. Markham Hood Cleaning provides the quote in a form that can be handed to a property manager, with the roof condition photographs attached.
Will containment affect the exhaust fan's performance?
Correctly sized containment does not restrict the discharge, because it collects around the outflow rather than blocking it. An undersized box or one that has been left unserviced until the media is saturated is a different matter, and that is exactly why the service interval is set from cooking volume rather than left open ended.
The roof already has grease staining. Is it too late?
No, and documenting it is the priority. The assessment photographs the existing condition before anything is fitted, which establishes what predates the containment. Fitting then stops further contact. Whether the existing staining needs a roofer is a question for a roofing contractor, and Markham Hood Cleaning will say so rather than quoting work outside its trade.
How often does the absorbent media need changing?
It follows the same logic as the cleaning interval: the heavier the cooking, the faster the media loads. A high-volume wok or fry line usually needs it each time the hood is serviced, while a lighter line can go longer. The interval is set at the assessment and revisited if the menu or the hours change.
Does containment replace cleaning the fan?
No. Containment catches what the fan discharges outward. Grease still coats the fan housing and the blower wheel on the inside, and a coated wheel loses balance and moves less air. The fan is lifted and cleaned as part of the exhaust system visit, described on the kitchen exhaust cleaning page.