There is no per-foot number that survives contact with a real site. Load class, what is in the water, whether an interceptor is required, and how much of the work has to happen after hours each move the total more than the channel itself does.
Residential trench drains price in a predictable band because the job is largely the same everywhere: a driveway, a known load, and a findable outlet. We publish $1,800 to $4,500 for that work because it is honest to do so.
Commercial does not behave that way. Two sites with an identical fifteen-metre run can differ by a factor of three or more, and the difference is almost never the channel. It is the load class the traffic demands, what the water contains and where it is legally allowed to go, whether an interceptor exists and is adequate, and how much of the work has to happen outside your operating hours.
A per-linear-foot figure quoted before the discharge route is established generally prices the channel alone, leaving the rest to a change order.
In rough order of how much they change the total on a typical GTA commercial site.
This is the largest single variable and the one most often skipped. Clean surface runoff goes to storm. Wash water needs an interceptor. Process effluent may need pretreatment and a discharge agreement with the municipality. Each step up changes both the material and the scope well beyond the channel.
C250 for a service bay, D400 for a loading dock or delivery lane, E600 or F900 where forklifts and heavy plant cross. Grate and frame cost rises steeply with class, and forklifts specifically demand bolted grates and edge protection that lighter duty does not.
Polymer concrete covers a wide range of commercial duty. Stainless 304 or 316 is required where chemistry, temperature, or hygiene demand it — car wash bays, food processing, healthcare. Hygienic channel with radiused corners and built-in fall is fabricated rather than stock, and priced accordingly.
A dealership that keeps its bays open, a hospital wing that cannot close, a plant that only stops at the weekend. Phasing and after-hours work are genuine cost, and on constrained sites they can rival the drainage scope itself. We show them as separate lines rather than burying them.
Thickness, reinforcement, and existing services below the cut line all affect excavation. A reinforced industrial slab is a different job from a plaza apron, and unknown services under the run are the most common source of a genuine mid-job change.
A back-of-house plant floor and a customer-facing showroom entrance need very different finishes. Where the result has to look deliberate rather than merely functional, restoration labour goes up.
If you are comparing quotes, compare what is included rather than the bottom line. The gap between commercial quotes is usually scope, not margin, and the cheap one is frequently the one that has left the expensive part out.
A quote that does not name the discharge route has not established it. That is the single most useful thing to check before signing anything.
None of these are the channel. All of them are avoidable at the quoting stage.
A site has an interceptor, so everyone assumes it is fine. It was sized for a smaller operation, or it has not been pumped in years. Discovering that after the drain is installed means doing the expensive part twice.
A warehouse spec applied to an aisle that forklifts cross all day. The grate is technically rated for the building and fails within a year under the actual contact loading. Spec follows what crosses the drain, not what the building is called.
The most expensive assumption available. If process or wash water is going somewhere it should not, the fix is not a drainage change — it is a compliance remediation, and it arrives with a deadline attached.
Production or service resumes early on a fresh pour, the patch cracks under the first heavy crossing, and the section is redone inside a month. The cure window is not padding.
A quote assuming free run of the site, issued to a facility that cannot give it. The revised schedule then arrives as a change order rather than having been in the original number.
Commercial drainage is rarely bought for its own sake. It is bought because water is costing something — downtime, a slip claim, a failed inspection, a surcharge, or slab damage that compounds every winter.
The specification decisions that cost more up front are almost always the ones that stop the job being done twice in a live facility, which is far more disruptive and expensive than doing it correctly the first time.
The questions facility managers, GCs, and owners ask before a site visit.
Because it would be misleading in most cases. On a commercial site the channel is frequently a minority of the total. Load class, interceptor requirements, discharge compliance, and after-hours phasing move the number far more, and none of them can be assessed from a description. A per-foot figure quoted blind is either the channel alone with everything else arriving as change orders, or a guess padded to cover the unknowns.
A site visit, and answers to three questions we will ask during it: what crosses the drain, what is in the water, and what hours we can work. Those three set the load class, the material and interceptor requirements, and the phasing. With them we issue a fixed, itemised quote.
Residential driveway work sits in a predictable $1,800 to $4,500 band because the variables are narrow. Commercial has no equivalent band — two sites with the same run length routinely differ by a factor of three or more once load class, discharge, and access are accounted for. That is why we publish a residential range and quote commercial after seeing it.
Fixed, once we have done the site visit and established the discharge route. The exception is genuinely unknown services under the run, which we call out as a named risk with an agreed process rather than discovering mid-job and issuing a surprise.
Yes. On projects with a mechanical consultant we price to their specification and provide shop drawings for review. Where we think a specified detail will not perform in service — an unprotected channel edge in a forklift aisle, for instance — we raise it before installing rather than after.
Yes, and it is usually worth doing together. Standardising the specification across a dealership group or a portfolio of facilities makes grate replacement and maintenance far simpler later. Each site still gets its own visit, because discharge routes are never identical.
Typically two to seven days on site depending on scope and phasing, plus a cure window of 48 to 72 hours before heavy traffic returns. Phased work on an operating site runs longer in calendar time but keeps the facility trading throughout, which is usually the trade worth making.
We will tell you plainly, and we will not tie new drainage into a non-compliant route. It is not a comfortable conversation, but finding out from us during a quote is considerably better than finding out from an inspector, and it changes what the right scope of work is.
Free site visit across the GTA. We'll tell you what you actually need — no upsell.
