Rough-in day locks your bathroom plumbing into the wall, often weeks before the vanity arrives on site. If the drain and supply stub-outs land in the wrong spot, you are looking at opened drywall, a hacked-up cabinet back, or a trap that will not fit behind the drawers. Fortunately, vanity plumbing rough-in height follows predictable ranges, and a few measurements from the actual vanity you plan to buy will keep everyone out of trouble, whether the job site is in Vancouver, Winnipeg or Halifax.
The rule that prevents most problems: measure the actual vanity
Every "standard" number below assumes a conventional floor-standing vanity with open space behind the doors. Real products vary more than people expect: a shallow unit may have a narrow plumbing zone, and a wall-hung vanity with full-width drawers may accept a drain only within a tight band. Before rough-in, pull the specification sheet for the exact model, find the plumbing cutout or clearance diagram, and hand those pages to your plumber. Our guide to reading a plumbing spec sheet before ordering shows where those drawings live.
If the vanity has not been chosen yet, choose it before rough-in, or at least settle the category, because floor-standing, wall-hung and vessel-top designs each shift the numbers. Browsing the vanity collection with your contractor early costs nothing and saves a service call later. Sizing questions are covered in our bathroom vanity size guide.
Typical rough-in heights for a standard floor-standing vanity
These are widely used working ranges in Canadian residential construction, not code requirements. Your local code, your inspector and your specific fixtures always take precedence.
| Rough-in element | Common range above finished floor | Notes |
|---|---|---|
| Drain (waste stub-out) | 18 to 20 in (about 45 to 51 cm) | Centred under the basin drain, not the cabinet, which matters on offset-bowl vanities |
| Hot and cold supply stub-outs | 20 to 24 in (about 51 to 61 cm) | Slightly higher than the drain so shut-off valves and the trap do not compete for space |
| Supply spacing | About 4 in (10 cm) each side of the drain centreline | Hot on the left, cold on the right, viewed facing the wall |
Two details are worth flagging. "Finished floor" means the surface you will walk on, so if rough-in happens before tile, the plumber needs the total floor build-up, including any in-floor heating. And taller "comfort height" cabinets give a little more forgiveness below the basin, while furniture-style pieces with a low shelf give less. That is why the spec sheet beats the rule of thumb.
Wall-hung vanities: the drain becomes part of the look
Wall-hung vanities are where rough-in height stops being invisible. With no legs and often no back panel, the space beneath the unit is open to view, and on shallow designs the trap can sit partly in sight. Three things change.
- The drain usually moves up. Many wall-hung designs want the waste stub-out higher than the traditional range so the trap tucks behind or above the drawer boxes, and the acceptable band is often narrow.
- Exposed hardware matters. If the trap will be visible, a decorative bottle trap or an in-wall trap kit is worth planning while the wall is still open. The sink drains and trap hardware collection covers the options.
- Blocking is part of the rough-in. Wall-hung cabinets carry their load into the studs, so solid backing goes in at the same visit as the plumbing, set out against the same mounting diagram.
Brands that specialize in floating designs, Duravit and ICO Bath among them, publish detailed installation drawings for this reason. If you are comparing models, start with the wall-mount vanity collection.
Vessel sinks: the change happens above the counter
A vessel sink sits on top of the counter, raising the rim by roughly the height of the bowl. Below the counter, the rough-in often looks similar to a standard vanity, though the drain may shift up slightly because the trap connects through the countertop to a shorter tailpiece. Two planning points come up constantly.
- Counter height usually drops. To keep the rim at a comfortable washing height, many vessel installations use a lower cabinet so the bowl lands near standard rim height. Confirm the combined height before rough-in.
- The faucet has to reach. A standard-height faucet will not clear a vessel rim. You need either a tall single-hole model or a wall-mount faucet, and that decision affects the wall, not just the counter. The vessel sink collection pairs naturally with tall spouts from the bathroom faucet collection.
Wall-mount faucets: plan before the drywall goes on
Wall-mount faucets put the valve body inside the wall, so height, centreline and depth are all committed at rough-in. As a general rule, the spout sits a few inches above the basin rim, high enough to clear the bowl and low enough to limit splash, with the stream falling near the drain. Because rim height depends on the vanity, counter and sink together, this is where the measure-the-actual-vanity rule is non-negotiable.
Depth matters too: every wall-mount valve has a specified rough-in depth range measured from the finished wall surface, so the plumber needs to know the wall build-up, including tile. If the two-box system of valves and trim kits is new to you, our explainer on why faucets come in rough-in and trim boxes covers ordering the parts in the right sequence. Riobel, Aquabrass and Brizo all publish rough-in documents for their wall-mount lavatory lines.
Canadian code and cold-climate notes
Canada works from the National Plumbing Code as a model, but each province and territory adopts and amends it on its own schedule, with municipal permits and inspections on top. Treat every range here as planning guidance and let your local plumber confirm venting, trap arrangement and pipe sizing against the code where you live. Fixtures sold for Canadian installation should carry recognized certification; our guide to CSA and cUPC certifications explains what those marks mean at inspection time.
One genuinely Canadian consideration: think twice before running supply lines in an exterior wall. From the Prairies to the Maritimes, that puts pipes on the cold side of the insulation, and a hard snap can freeze them. Where an exterior wall is unavoidable, insulation detailing and warm-side pipe placement become part of the rough-in conversation.
Frequently asked questions
What is the standard rough-in height for a vanity drain?
A common working range is 18 to 20 inches above the finished floor for a standard floor-standing vanity, with supply stub-outs a few inches higher. Wall-hung vanities and some vessel installations move the drain up, so confirm against the specific vanity's installation drawing and your local code.
Can I install a wall-hung vanity on existing standard-height plumbing?
Sometimes, but check the drawer clearances first. Many wall-hung designs need the drain higher than a typical rough-in so the trap clears the drawer boxes. If the existing stub-out falls outside the manufacturer's acceptable zone, plan on opening the wall to relocate it.
Do vessel sinks need a different drain rough-in height?
Often only slightly. The bigger changes are above the counter: the cabinet is frequently lower so the raised rim stays comfortable, and the faucet must be a tall deck-mount or wall-mount model. Confirm the combined cabinet, counter and bowl height before rough-in.
How high should a wall-mount faucet be above the sink?
As a general guideline, the spout outlet sits a few inches above the basin rim, positioned so water falls near the drain. The exact number comes from the faucet's rough-in document and the real rim height of your vanity and sink combination, so do not set the valve until both are known.
