Hollow Metal & Commercial Steel Doors

A hollow metal door is the commercial door most people never look at: the rear entrance, the stairwell, the mechanical room, the door between the warehouse and the office. It is two formed steel face sheets around a core, hung in a steel frame, and it is the default for commercial openings in Ontario for three reasons — it holds its shape, it can carry a fire label, and every part of it can be repaired rather than replaced.

Canuck Door Systems has been supplying, installing and repairing those openings across the GTA since 1979. Most of what ranks for "commercial steel doors" is manufacturers and distributors selling the leaf. We measure the opening, specify the assembly, order the prep, install it with our own crews, and come back when the closer fails four years later. Most of our hollow metal doors and frames come from All Steel Doors Ltd in Scarborough and from Trillium, and we install and service other makers' doors and frames too.

Steel doors, frames and finishes we supply and install

The assembly

A steel opening is a door, a frame and the hardware prep between them — the frame decides more of the job than the leaf does.

• Steel Door Frames

  Hollow metal frames in 16 and 14 gauge, knock-down or welded — supplied with the door or on their own, and repaired when the frame is what failed.

• Stainless Steel Doors

  Type 304 and 316 stainless doors and frames for washdown, food, pharmaceutical and lab openings, where a painted steel door does not survive.

What "hollow metal" actually means

Not that the door is empty. The name describes the construction — two steel face sheets formed around the edges and joined, with a core filling the cavity between them. What goes in that cavity is a specification, and it is where most of the performance of the door is decided.

Gauge, and what the levels mean

Steel thickness is quoted in gauge, and lower is thicker. The trade shorthand is ANSI/SDI A250.8, which sorts doors into four levels by face-sheet gauge and construction — a number a specifier writes and a distributor quotes against.

Frames run one step heavier than the door they carry: 16-gauge is the usual interior frame, 14-gauge the exterior and heavy-duty one. The frame is the part that takes the abuse — it is what a cart hits, what a hinge pulls against, and what rusts first at grade.

Standard sizes, and the rough opening

Commercial steel doors are built to a size grid rather than to whatever the opening happens to be, and a door on the grid is faster and less expensive than one off it. The commercial default is a 3'0" × 7'0" single leaf.

The rough opening is not the door size. For a hollow metal frame with a standard 2" face, the masonry opening is the nominal door size plus 4" in width and 2" in height — two inches of frame face at each jamb, one at the head. Crews working to a field-shimmed tolerance add roughly another half inch of width and a quarter inch of height so the frame can be plumbed rather than forced. A pair uses the same arithmetic on the pair width, not on one leaf. Confirm it against the frame schedule before the wall goes up: a masonry opening built to the door size instead of the frame size is the most expensive measurement error on a steel-door job.

A door on the size grid in a common gauge and prep can ship in days. Take it off the grid — an odd width, a ten-foot height, an unusual prep — and it joins the 4–6 week production queue. When an opening is close to a standard size, framing to the standard is almost always less expensive than ordering the door to the wall.

Single doors and pairs

A pair is not two doors. It is one opening with an active leaf, an inactive leaf and a set of parts that make the two behave as one — and most of what goes wrong with a double door is in those parts rather than in either leaf.

• Active and inactive leaf — the active leaf carries the lock or exit device and is the one people use. The inactive leaf is held shut by flush bolts and opened only when something wide has to pass.
• Astragal — the vertical closure where the leaves meet. An overlapping astragal on the active leaf is the common choice, a T-astragal mounts between the leaves, and a rated pair needs a labelled steel one that does not obstruct egress.
• Flush bolts — manual bolts into the head and floor of the inactive leaf, or automatic bolts that throw when the active leaf closes. Rated pairs generally require automatic bolts, because a manual bolt someone left open is an unlatched fire door.
• Coordinator — on a closer-equipped pair, the device that makes the inactive leaf close first so the astragal lands in the right order. Without one the two doors fight and neither latches.
• Removable mullion — a vertical post between the leaves that lets each leaf behave as a single door with its own latch, then lifts out when a skid has to come through. It is how a 6'0" pair passes freight and still latches and rates.
• Rated pairs — every part of the assembly is labelled and the gap at the meeting stiles is held to about an eighth of an inch. It is the first detail an inspector checks on a pair.

Pairs earn their cost where something wide moves — receiving doors, equipment rooms, corridors between departments — and cost money everywhere else, because there are twice the leaves and three times the hardware to keep in adjustment.

Where steel doors go

Eight openings account for most of the steel doors in a commercial building. The common thread is that the door has a job other than being looked at.

Frames: knock-down or welded

The frame is half of the assembly and most of the decision. Two families cover commercial work.

Frame profile, throat size and anchor type all follow the wall, which is why we measure the wall rather than the old door. The frame page covers the profiles, anchors and repairs in detail: steel door frames.

Exterior openings: weather, drainage and the finish that fails here

Three finishes cover commercial steel, and the wrong one at an exterior opening is the most common avoidable failure we see.

• Factory primed — a rust-inhibitive primer for painting on site. Interior openings only; primer is not a finish, and left unpainted outdoors it will rust within a season.
• Galvannealed (A60) — a zinc-iron coating bonded to the sheet before the door is made. It takes paint, and it stops rust spreading under a scratch. This is the specification for anything exterior in this climate.
• Stainless steel — type 304 or 316, for washdown, chemical exposure, coastal-grade humidity and the kitchens and plants where the cleaning regime destroys paint. See stainless steel doors.

Salt is what kills a steel door in Ontario, not water — a primed door 12 inches from a salted loading pad has a hard life. Galvannealed with a proper paint system, and a bottom rail you can see and wash, is the difference between a 20-year door and a 5-year one.

Finish is the half of an exterior opening people remember to specify. The other half is everything that keeps water moving away from the door:

• Thermal break — a leaf and frame that separate the outside face from the inside one, so the door does not condense and freeze at the rebate on a January morning. Worth it on a heated opening, unnecessary on an unheated warehouse wall.
• Sweep and threshold — the sweep closes the gap under the leaf and the threshold gives it something to seal against while getting water back outside. A three-quarter-inch undercut with no threshold is a heating bill and a puddle.
• Drainage at the sill — a welded frame set into masonry needs its base grouted and the sill detailed so water leaves rather than sits. Frames rust from the inside out, at the floor, where nobody looks.
• Wind and gasketing — an exposed elevation on a tall building can load a door hard enough to unlatch it. Perimeter gasketing and a correctly sized closer are the fix.

A galvannealed leaf in a primed frame still rusts at grade, because the frame is what stands in the salt — specify the finish for the assembly, not for the door. The seals and sweeps themselves are covered on commercial door weatherstripping. When an exterior door is already failing — dragging, not latching, rusted through at the bottom rail — that is usually a repair rather than a replacement: see commercial door repair, or 24/7 emergency door repair if it will not lock tonight.

Glazing: vision lites and glass

A steel door takes glass in a cut-out with a steel or aluminum lite frame around it, and that cut-out is made at the factory with the rest of the prep. What changes from opening to opening is how much glass there is and what the glass has to survive.

Two constraints decide the glass itself. A rated opening limits the glazed area and requires labelled fire-rated glazing — traditional wired glass, or more usually now a ceramic or filmed product that meets the rating without the wire — and the lite frame has to carry a label too. A non-rated opening is a safety-glass question instead: tempered where breakage is the risk, laminated where security or sound is. On a pair, glass in the two leaves has to line up, which is a shop-drawing detail worth checking before the doors are made rather than after.

Hardware prep: decided before the door is made

A hollow metal door is prepped at the factory, not on site. Hinge locations, lock cutouts, closer reinforcements and strike positions are cut and welded into the leaf and frame before they leave the plant, and after that they are effectively fixed.

• Hinges — butt hinges to a standard ANSI location, or a continuous geared hinge on high-traffic and abused openings.
• Locks & exit devices — mortise (ANSI 161), cylindrical, or an exit device on anything on an exit path; the leaf is reinforced for whichever it is.
• Closers — surface-mounted, concealed in the frame, or overhead with a hold-open, with the reinforcement inside the door.
• Electric hardware — electric strikes, maglocks, power transfer hinges and card readers, which need wiring paths designed into the frame.
• Glazing & louvres — lite and louvre cut-outs are made at the same stage as the hardware prep, which is why the glazing has to be settled before the door is ordered.

Getting hardware right at the measure is the single biggest schedule risk on a steel-door job. Deciding it after the door is made usually means a new leaf.

Steel door work across the GTA

Recent hollow metal jobs from our own records. These are documented as dated job folders in the company photo library rather than as written project briefs, so we list what we can state accurately — the client and the date.

• Omni King Edward HotelDecember 2025
• St. Joseph's Healthcare Hamilton (with Complete Concrete)October 2024
• Canada's WonderlandMay 2025
• Mariani Metal FabricatorsFebruary 2026
• Frost Products LtdFebruary 2025
• SMiD Construction LtdMay 2024
• Seven Building Services Inc.March 2025
• Cathedral Court Co-opJuly 2025

Seven steel door jobs are written up in full: eighty-nine exterior doors across three ramps of a hospital parking garage, painted before winter and replaced one ramp at a time — parking garage steel doors for St. Joseph's Healthcare Hamilton; fifty-three warehouse doors with glazed transoms, ordered from the drawings — warehouse hollow metal doors on Solar Drive, Mississauga; the back-of-house doors and frames for a new retail store, frames delivered first — steel doors and frames for Toys “R” Us in North York; eighteen hollow metal doors in welded frames with grade 1 hardware, ordered from the drawings before the openings were built — interior commercial steel doors in Brampton for Curaleaf; fifteen stairwell doors with sidelites in a hospital parking garage that never closed — hollow metal doors for Grand River Hospital in Kitchener; seventeen pairs of electrical room doors, each finished and locked the day it was started — double metal doors replacement in Toronto; and twelve hollow metal doors alongside the glass on two buildings readied for tenants — 777 Warden Avenue, Scarborough.

Steel openings for names Ontario knows — Canada’s Wonderland, Tim Hortons, Canadian Tire, the LCBO, Metrolinx, Marriott & Hilton hotels, the University of Toronto — plus thousands of plants, schools, condos and businesses across the GTA. Dependable people, quality products, since 1979.

“The technician that installed our New door and Frame did an awesome job and was very respectful. He left his work area clean and tidy before leaving.”

Ken O., Google review