Most people never think about the frame around a commercial door until something goes wrong with it. The door sticks, the latch stops lining up, rust creeps up from the floor, or a fire inspector flags the opening. In almost every one of those cases the real problem is the frame, not the door leaf. On a commercial building the frame is the part that carries the hinges, holds the strike, anchors into the wall, and often carries the fire label for the whole opening.
If you own or manage a property in the Greater Toronto Area, steel door frames are probably behind more of your entrances than you realize. They sit behind storefront service doors, stairwell exits, mechanical rooms, washrooms, warehouse openings, and nearly every fire separation in the building. This guide walks through what a steel door frame actually is, the frame types you will run into, how they are sized and anchored, what the Ontario code expects, and how to tell when a frame needs repair instead of full replacement.
What is a steel door frame?
A steel door frame is the formed metal assembly that surrounds a door opening and holds the door in place. It is made from bent sheet steel and includes two vertical jambs and a head, prepped to receive hinges, a strike, and often a closer. In commercial construction these are usually called hollow metal frames, and they carry the load, the hardware, and any fire rating for the opening.
Steel frames matter because they do far more than trim out an opening. The frame is what keeps a heavy commercial door hanging square for decades of daily use, and it is the piece a burglar, a fire, or a careless delivery cart tests first. A weak or poorly anchored frame will loosen, rack out of square, and drag the door out of alignment no matter how good the door itself is.
Is a steel door frame the same as a hollow metal frame?
In commercial work, yes, the two terms describe the same product. “Hollow metal” refers to the way the frame is formed, from cold-rolled or galvanized sheet steel bent into a hollow profile, rather than solid bar. When a supplier lists a “hollow metal door frame” and another lists a “commercial steel door frame,” they are almost always talking about the same category of product. Residential steel frames exist too, but they are lighter and built to a different standard than the commercial hollow metal frames covered here. If you want the door side of this equation, our guide to hollow metal commercial steel doors covers gauges, cores, and door types in the same detail.
Why GTA commercial buildings rely on steel frames
Steel frames win in commercial settings for four practical reasons: durability under heavy traffic, resistance to fire when tested and labeled, better security than wood or aluminum, and the ability to hold heavy hardware without tearing out. The Canadian Steel Door Manufacturers Association points out that hollow metal takes far more physical abuse than wood, aluminum, or fiberglass and is easier to keep clean and maintain, which is why it dominates institutional and industrial openings. For a broader comparison of frame and door materials, see our breakdown of whether a steel or aluminum door is better for your business.
The anatomy of a hollow metal door frame
Before you can choose or spec a frame, it helps to know the parts, because suppliers and installers use this vocabulary constantly. The Steel Door Institute defines each element of the profile, and once you can picture them, measuring and ordering gets much easier.
| Frame part | What it is | Why it matters |
|---|---|---|
| Face | The visible flat surface of the frame you see from the side of the wall | Sets the trimmed look of the opening; commonly about 2 inches wide |
| Stop | The raised element the door closes against | Controls how the door seats and where weatherstripping or gasketing sits |
| Rabbet | The recess between the stop and the face that accepts the door, panel, or glazing | Must match door thickness; a 1-3/4 inch door needs the correct rabbet depth |
| Soffit | The surface between the stops, or between stop and face on a single rabbet | Part of the profile that defines single versus double rabbet frames |
| Throat opening | The distance between the returns, sized to the wall thickness | The frame wraps the wall, so the throat must match your actual wall build-up |
| Return and backbend | The edges that turn back toward and along the wall inside the throat | Grip the wall and, on drywall frames, wrap the wallboard |
| Single vs double rabbet | One rabbet for a single swing, two for pairs or communicating openings | Determines how many doors and which way they seat |
| Cased opening | A frame with no stop or soffit, essentially a lined pass-through | Used where no door is needed but the opening still needs a finished steel edge |
Understanding these parts pays off the moment you talk to a supplier about replacing a door in an existing opening. The standard commercial door sizes that fit a frame depend on the rabbet and the frame’s prepped opening, so the frame and the door always have to be specified together.
Steel door frame types by construction and installation
Frames are grouped by how they are built and how they go into the wall. The right choice depends on whether the wall is already standing, what it is made of, and how much abuse the opening will take. Here are the types you will actually encounter in GTA commercial buildings.
Knock-down (KD) frames
A knock-down frame ships flat in three or more pieces and gets assembled on site, with the head slipping into the jambs and locking together with tabs or gussets. KD frames are inexpensive, easy to transport, and quick to install, which makes them the default for interior drywall partitions and light-duty openings. The trade-off is rigidity. A KD frame is only as square as the crew that assembles it, so it is not the first pick for heavy traffic or high security.
Welded frames
A welded frame arrives as one rigid unit with the corners continuously welded, ground smooth, and factory finished. Welded frames are stronger, hold their square under abuse, and are the standard choice for exterior openings, high-traffic entrances, security doors, and most fire-rated assemblies. They cost more and have to be set before or as the wall is built in masonry, but they last. When a client asks us to spec an opening that has to take carts, crowds, or forced-entry attempts, a welded frame is almost always the answer.
Drywall and slip-on frames
Drywall frames, sometimes called slip-on or wrap-around frames, are designed to install after a stud-and-wallboard wall is already finished. The frame’s backbends wrap over the drywall and clamp the wall between them. These are a clean retrofit option when you cannot tear open a partition, and they are common in office fit-ups and tenant improvements across the GTA.
Expandable and adjustable frames
Expandable frames adjust to fit a range of wall thicknesses, which is why you see them sold for retrofit work. The listings we reviewed this year describe adjustable steel frames that wrap walls from roughly 4-5/8 inches to 7-3/4 inches thick. They save you from measuring the wall perfectly before ordering, though a fixed welded frame is still the sturdier long-term answer for a demanding opening.
Knock-down vs welded: which should you choose?
| Factor | Knock-down (KD) | Welded |
|---|---|---|
| Assembly | Field-assembled from flat pieces | Arrives as one welded unit |
| Strength and squareness | Good for light duty, depends on install quality | Highest, holds square under heavy use |
| Best wall type | Interior drywall partitions | Masonry, exterior, high-traffic, fire-rated |
| Install timing | After the wall is built | Usually before or during wall construction |
| Relative cost | Lower | Higher |
| Typical use | Offices, washrooms, storage rooms | Entrances, stairwells, mechanical, warehouse |
Frame gauges: how thick should a commercial steel frame be?
Frame strength comes down to steel thickness, and thickness is specified by gauge. The lower the gauge number, the thicker and stronger the steel. Commercial hollow metal frames follow ANSI/SDI A250.8, the Steel Door Institute standard that pairs door performance levels with minimum steel thicknesses for both doors and frames.
| Performance level | Frame steel gauge | Thickness | Where it fits |
|---|---|---|---|
| Level 1, standard duty | 18 gauge | 0.042 in (1.0 mm) | Light interior openings, low traffic |
| Level 2, heavy duty | 16 gauge | 0.053 in (1.3 mm) | General commercial traffic |
| Level 3, extra heavy duty | 16 gauge | 0.053 in (1.3 mm) | Busy entrances, schools, healthcare |
| Level 4, maximum duty | 14 gauge | 0.067 in (1.7 mm) | Detention, industrial, extreme abuse |
For most GTA commercial buildings, a 16 gauge welded frame handles day-to-day duty well, while 14 gauge shows up on the toughest industrial and security openings. The steel itself also matters: cold-rolled steel is standard for dry interior openings, while galvanized or galvannealed steel is used for exterior frames and damp or corrosive spots like loading docks and wash-down areas, where road salt and moisture would otherwise start rust at the base. If you are matching a frame to a specific door, our commercial door hardware guide explains how the frame’s reinforcements have to line up with the hinges, strike, and closer you plan to hang.
Throat, face, and rough opening: sizing a frame to your wall
A steel frame has to match two things: the door it holds and the wall it wraps. Get either wrong and the opening never sits right. Two numbers do most of the work here, the throat opening and the rough opening.
The throat opening is the clear distance between the frame’s returns, and it has to equal the finished thickness of your wall. A frame sized for a 4-3/4 inch throat will not wrap an 8 inch block wall. Throat sizes track common wall build-ups, so a stud-and-drywall partition, a single-wythe block wall, and a thick masonry wall each call for a different throat. Expandable frames exist precisely because retrofit walls are rarely a perfect standard thickness.
| Wall type | Typical throat range | Common frame choice |
|---|---|---|
| Steel stud and single-layer drywall | About 4-3/4 in | Drywall slip-on or KD frame |
| Stud with double drywall or thicker partition | About 5-3/4 in | Drywall or welded frame |
| Single-wythe concrete block | About 6-3/4 in | Welded masonry frame |
| Thick or furred masonry | About 8-3/4 in and up | Welded masonry frame |
When you replace a door in an existing steel frame, the Steel Door Institute recommends measuring the opening width and height at three points and using the smallest reading, since old frames rack over time. That single habit prevents most of the “the new door does not fit” calls we get. For a full treatment of opening dimensions and clear width, our complete guide to standard commercial door sizes is the companion piece to this section, and if the opening serves the public you also need to check accessible clear-width rules.
How steel door frames are anchored to the wall
A frame is only as solid as its connection to the wall. The anchors are what stop the frame from loosening, twisting, and dragging the door out of square, and the right anchor depends entirely on what the wall is made of. The Steel Door Institute defines several anchor families for exactly this reason.
| Anchor type | Wall it suits | How it works |
|---|---|---|
| Masonry wire anchor | New block or brick | Loose wire tie set into the mortar joints as the wall is laid |
| Existing masonry anchor | Standing block, brick, or concrete | Prepped hole for an expansion bolt, machine bolt, or screw |
| Steel or wood stud anchor | Stud-framed partitions | Metal device that fastens the jamb to the studs |
| Floor or base anchor | All frame types | Clip at the bottom of each jamb bolted to the floor |
Quantity and spacing matter as much as the anchor type. Industry guide specifications call for a minimum of three anchors per jamb on a standard opening, with more added as the frame gets taller, and floor anchors at the base of each jamb. In concrete and masonry walls, the frame is filled solid with grout so it cannot flex or get crushed. That grout fill is also what gives a masonry frame much of its fire and impact resistance. Skipping it, or under-anchoring a frame, is one of the most common reasons a frame loosens and the door starts binding a few years later. If your doors already bind or drag, our article on why a commercial door makes a grinding noise traces the usual causes back to the frame and hinges.
This is also where professional installation earns its keep. A frame set plumb, square, grouted, and properly anchored will outlast the building’s finishes. A frame slapped in loose will haunt you. Our commercial door installation team sets frames to these standards across the GTA, and for a sense of what a full opening involves, the cost of commercial door installation in Toronto breaks down the labour side.
Fire-rated steel door frames and the Ontario Building Code
Steel frames do a lot of quiet work on the fire-safety side of a building. In any fire separation, the frame is part of a tested and labeled assembly that includes the door, the frame, and the hardware. You cannot mix a fire-rated door into a random frame and call the opening rated. The whole assembly has to be listed together.
The Ontario Building Code sets the required closure rating for each fire separation. Under Ontario Building Code provision 3.1.8.4, a separation with a given fire-resistance rating requires a door and frame assembly with a specified fire-protection rating, so a common 1 hour separation calls for a 45 minute rated closure, and a 2 hour separation steps up from there. Those assemblies are tested to CAN/ULC-S104, the Canadian standard method for fire tests of door assemblies, and they carry a permanent label. Fire-rated frames in masonry are grouted, welded construction is typical at higher ratings, and any field modification that is not permitted by the listing can void the label.
Because the frame is part of the rated assembly, replacing or repairing it wrong is a code issue as much as a maintenance one. Our detailed pieces on Ontario Building Code fire door requirements and on fire-rated doors, ratings, and types go deeper on the labeling and rating tables, and the code-compliant fire-rated door checklist is a quick way to self-audit an exit before an inspection. If you are unsure whether your existing openings still meet current rules, start with our checklist on whether your current doors are up to the Ontario Building Code.
Hardware prep: hinges, strikes, and reinforcements
A commercial frame is not a blank piece of steel. It comes prepped with welded-in reinforcements and cut-outs at the exact points where hardware attaches, so the door hangs true and the parts stay interchangeable. Hinge reinforcements sit on the hinge jamb, a strike cut-out sits on the opposite jamb, and closer reinforcements sit at the head. Because these locations follow Steel Door Institute standards, a properly made frame accepts standard hardware without custom fitting. The most common commercial hinge height is 4-1/2 inches, and the common strike is 4-7/8 inches.
Getting the reinforcement gauge right is what lets a frame carry a heavy closer or an electrified strike without tearing. When you plan the opening, the frame prep, the door, and the hardware all have to be specified together. Our guides to commercial door locks, electric strikes and access control, and panic bars and exit devices each depend on the frame being prepped to suit, and worn hinges pulling out of a tired frame are a frequent trigger for commercial door hinge replacement.
Common steel door frame problems in GTA commercial buildings
Steel frames are tough, but they are not immune to the Ontario climate and daily commercial abuse. Here are the failures we see most often, and what actually causes them.
| Symptom | Likely cause |
|---|---|
| Rust creeping up from the floor | Road salt and standing moisture at the base, no galvanized steel, failed paint |
| Door binds or scrapes the frame | Frame racked out of square, loose anchors, or seasonal movement |
| Latch or strike no longer lines up | Jamb shifting, worn hinges, settled anchors |
| Hinges pulling loose from the jamb | Stripped reinforcement, overweight door, or under-gauge frame |
| Dented or bowed face and jamb | Impact from carts, forklifts, or deliveries |
| Paint bubbling or peeling | Moisture behind the finish, often the first sign of hidden rust |
Heat and humidity make several of these worse over a Toronto summer, since steel expands and any binding gets tighter. We cover that seasonal pattern in commercial door problems that get worse with heat and humidity. When a frame is damaged at an entrance that has to stay secure overnight, that becomes an emergency commercial door repair rather than a scheduled fix.
Repair or replace a steel door frame?
Not every frame problem means tearing out the opening. Steel frames are repairable in ways wood and aluminum are not, but there is a point where replacement is the smarter spend. Here is how we weigh it.
| Lean toward repair when | Lean toward replacement when |
|---|---|
| Surface rust or a dented face that can be treated and refinished | Rust has eaten through the steel at the base or anchors |
| Loose anchors that can be re-secured and re-grouted | The frame is racked badly out of square and will not hold alignment |
| A worn strike or hinge reinforcement that can be repaired | A fire label is compromised or the assembly no longer meets code |
| The frame is otherwise sound and correctly sized | You are changing door size, rating, or hardware significantly |
The full decision framework, including how to factor downtime and total cost, is in our guide to repair versus replacement for commercial doors and windows. For fire-rated openings specifically, we handle both metal and fire-rated door repair and full metal and fire-rated door replacement so the assembly stays properly labeled either way.
What does a steel door frame cost?
Frame price depends on construction, gauge, throat size, finish, and whether it carries a fire label, so there is no single number. To give a grounded sense of the material side, the Canadian retail listings we reviewed this year ran from roughly $180 to $650 for the frame alone, with knock-down drywall frames at the low end and welded or fire-rated masonry frames at the high end. Those figures are for the frame only. Installed cost adds labour, anchoring, grouting, any wall work, and the door and hardware, and it climbs on masonry, exterior, and rated openings.
| Cost driver | Effect on price |
|---|---|
| Construction type | Welded costs more than knock-down |
| Gauge | 14 gauge costs more than 16 or 18 |
| Fire rating | Labeled assemblies add cost |
| Finish and steel | Galvanized for exterior costs more than cold-rolled |
| Wall type and access | Masonry retrofits and grouting add labour |
| Hardware prep | Extra reinforcements and electrified prep add cost |
For an accurate figure on your building, the only reliable path is a site assessment. You can contact our team for a free estimate and we will spec the frame, door, and hardware together.
Choosing and specifying the right frame
Pulling it together, the frame you choose comes down to four questions: is the wall already standing, what is it made of, does the opening need a fire rating, and how much abuse will it take. A new masonry stairwell wants a welded, grouted, fire-rated frame. An interior office retrofit wants a drywall or expandable frame. A busy exterior service entrance wants a galvanized welded frame in a heavier gauge. When you are planning a new build or a renovation, our guide to choosing the right commercial door walks through the same logic for the whole opening, and if the work touches the building envelope you may also need to check when Toronto businesses need permits before you start.
The practical takeaway is simple: the frame is the foundation of the opening, so it is worth specifying carefully and installing properly the first time. If you want a hand, our commercial door services cover frames, doors, and hardware across Toronto, Mississauga, Vaughan, Oakville, Barrie, and the wider GTA, including commercial door installation in Toronto.
Frequently asked questions about steel door frames
What is a steel door frame?
A steel door frame is the formed sheet-metal assembly that surrounds a door opening and holds the door. In commercial buildings it is usually a hollow metal frame with two jambs and a head, prepped for hinges, a strike, and a closer, and it often carries the fire rating for the opening.
Is a steel door frame the same as a hollow metal frame?
In commercial construction, yes. Hollow metal describes a frame formed from bent sheet steel into a hollow profile. Suppliers use “steel door frame,” “hollow metal frame,” and “commercial steel frame” interchangeably for the same product category.
What are the parts of a hollow metal door frame?
The main parts are the face, the stop, the rabbet, the soffit, the throat opening, and the return with its backbend. The face is the visible surface, the stop is what the door closes against, and the throat is the dimension that wraps your wall.
What is the difference between a knock-down and a welded frame?
A knock-down frame ships flat and is assembled on site, which is quick and cheap for interior drywall openings. A welded frame arrives as one rigid welded unit, holds its square under abuse, and is the standard for exterior, high-traffic, and fire-rated openings.
What gauge is a commercial steel door frame?
Commercial frames are typically 18, 16, or 14 gauge under ANSI/SDI A250.8. Sixteen gauge, about 0.053 inches thick, suits general commercial traffic, while 14 gauge is used on the heaviest industrial and security openings. Eighteen gauge is limited to light interior use.
What is the throat opening on a door frame?
The throat opening is the clear distance between the frame’s returns, and it must match your finished wall thickness so the frame wraps the wall correctly. Common throats track wall build-ups from roughly 4-3/4 inches for stud walls up to 8-3/4 inches and more for thick masonry.
How is a steel door frame anchored to the wall?
Frames use anchors matched to the wall: wire anchors set in mortar for new masonry, expansion or bolt anchors for existing masonry, stud anchors for framed partitions, and floor anchors at the base of each jamb. A minimum of three anchors per jamb is standard, with more on taller frames.
Do steel frames in masonry need to be grouted?
Yes. Frames set in concrete and masonry are filled solid with grout so they cannot flex or get crushed. The grout also adds fire and impact resistance, which is why skipping it is a common cause of loose, binding frames a few years later.
Can you buy just a frame for a door?
Yes. Steel door frames are sold on their own, as knock-down kits, welded units, or expandable retrofit frames. Just make sure the frame’s throat matches your wall and its rabbet and hardware prep match the door you plan to hang.
How much does a metal door frame cost?
The frame alone commonly runs from roughly $180 to $650 in the Canadian listings we reviewed, depending on construction, gauge, size, and fire rating. Installed cost is higher once you add labour, anchoring, grouting, and the door and hardware, so a site quote is the only accurate figure.
Can a steel door frame be installed in an existing wall?
Yes. Drywall slip-on frames wrap over a finished stud wall, and expandable frames adjust to a range of wall thicknesses, both designed for retrofit. For existing masonry, frames anchor with expansion or bolt anchors into the standing block or concrete.
What is a fire-rated steel door frame?
A fire-rated frame is part of a tested and labeled door assembly that resists fire for a set time. The frame, door, and hardware are listed together, the frame carries a permanent label, and under the Ontario Building Code the required rating depends on the fire separation it protects.
Do steel door frames rust?
They can, usually starting at the base where road salt and moisture collect. Galvanized or galvannealed steel and a sound paint finish resist it, and surface rust can often be treated and refinished. Rust that has eaten through the steel means the frame needs replacement.
How long do steel door frames last?
A properly installed and maintained steel frame commonly lasts for decades, often outliving the door leaf and much of the building’s finishes. Lifespan drops sharply when a frame is under-anchored, exposed to constant moisture without galvanizing, or repeatedly hit by traffic.
Can you repair a steel door frame or must you replace it?
Many frame problems are repairable, including surface rust, dents, loose anchors, and worn strikes. Replace the frame when rust has perforated the steel, the frame is badly racked, or a fire label is compromised. A quick assessment tells you which side of that line you are on.
What size rough opening do I need for a steel door frame?
The rough opening has to be larger than the nominal door opening to allow for the frame and setting clearances, and the exact figure depends on the frame profile and wall type. Follow the frame manufacturer’s rough-opening dimensions, and measure existing openings at three points using the smallest reading.
Are steel frames required by the Ontario Building Code?
The code does not require steel by material name, but it does require rated, labeled assemblies at fire separations, and steel hollow metal frames are the practical way most buildings meet that. For non-rated openings, material choice is yours, though steel remains the durable commercial default.
Talk to a GTA commercial frame specialist
Whether you are specifying frames for a new build, retrofitting an office, or dealing with a rusted, racked, or damaged opening, getting the frame right saves you years of binding doors and failed inspections. Our team works on steel and hollow metal frames, doors, and hardware throughout the Greater Toronto Area. Reach out for a free assessment and estimate and we will help you spec the right frame the first time.
The frame and the hinges carry the door together, so it is worth reading our guide to commercial door hinges alongside this one.
