Too Long; Didn't Read
- A steel door lite kit adds a vision window to a solid hollow-metal door using a two-piece frame, glazing tape, and tempered or fire-rated glass
- Standard commercial lite sizes range from 7" x 22" narrow lites to 22" x 58" full lites — the glass is always 1" smaller than the frame cutout
- Any lite over 100 square inches on a fire-rated door cuts the rating by 50 percent, so size selection matters
- Installation requires an angle grinder or plasma cutter to open the blank, plus internal reinforcement channels at the header and sill
- Brampton's Highway 410 corridor warehouses and Bramalea industrial units are prime candidates for lite kit retrofits on existing steel entry and corridor doors
You have a solid steel door on your Brampton commercial unit and you want to add a window without replacing the entire door. A steel door lite kit is the answer. It is a two-piece metal frame that sandwiches a pane of tempered or fire-rated glass into a rectangular cutout in the door face. The installer cuts the blank, welds in reinforcement, mounts the frame, and glazes the glass — and you get visibility, daylight, and safety without buying a new door. Here is how the process works and what to specify for your building.
What Is a Steel Door Lite Kit?
A lite kit — sometimes written "light kit" or called a vision lite — is a window insert for a commercial door. The word "lite" is an industry term for a pane of glass. The kit includes three components:
- Vision lite frame: A two-piece stamped steel frame (typically 18-gauge steel or stainless steel) that clamps around the glass from both sides of the door.
- Glass panel: Cut 1 inch smaller than the frame opening on each dimension. Common options are 1/4-inch clear tempered, wired safety glass, or fire-rated ceramic.
- Glazing tape: A closed-cell adhesive strip applied to the full perimeter of both sides of the glass. It cushions the glass within the frame and prevents rattling, water intrusion, and thermal transfer.
Together, these parts turn a solid hollow-metal door into a door with a factory-quality window. The two halves of the frame thread together through the door and clamp the glass and glazing tape in place. No welding is needed for the frame itself — only for the reinforcement of the cutout.
Why Brampton Commercial Properties Add Lite Kits
Brampton's industrial and commercial corridors — particularly along the Highway 410 strip, the Bramalea Road warehouse district, and the Steeles Avenue business parks — are full of 1990s and 2000s-era steel doors that were installed as solid blanks. That made sense at the time. But building use changes. A warehouse becomes a distribution centre with foot traffic. A back-of-house corridor becomes a shared hallway between two tenants. A solid steel door that once separated storage rooms now sits between an office and a shipping area where forklift traffic flows.
Many of these doors also have panic bar hardware that benefits from a vision lite so staff can see approaching traffic before pushing through. Adding a vision lite solves three problems at once:
- Safety. Staff can see who or what is on the other side before pushing through. This prevents collisions — a real concern in facilities where pallet jacks and foot traffic share corridors.
- Daylight. A half-lite or full-lite kit lets borrowed light pass between spaces, reducing the need for overhead fixtures in secondary rooms.
- Code compliance. Some occupancy changes under the Ontario Building Code require vision panels on corridor doors to meet egress visibility standards. A lite kit satisfies this without a full door swap.
The cost difference is significant. A new pre-glazed hollow-metal door plus frame and hardware runs $800 to $2,500 installed. A lite kit retrofit on an existing door typically falls between $250 and $600, including labour, for a standard non-fire-rated installation.
Lite Kit Sizes and How to Choose
Commercial door lite kits come in a range of standard sizes. The "order size" refers to the cutout in the door. The glass is 1 inch smaller. The visible glass (what you actually see) is 2 inches smaller than the order size because the frame overlaps by 1 inch on each side.
Common standard sizes:
| Order Size | Visible Glass | Typical Use |
|---|---|---|
| 7" x 22" | 5" x 20" | Narrow corridor peek lite |
| 12" x 12" | 10" x 10" | Small square visibility panel |
| 8" x 36" | 6" x 34" | Tall narrow strip lite |
| 18" x 18" | 16" x 16" | Medium square half-lite |
| 22" x 28" | 20" x 26" | Standard half-lite |
| 22" x 58" | 20" x 56" | Full-height vision panel |
The 100-square-inch rule matters. On a fire-rated steel door, a lite of 100 square inches or less (measured by the visible glass area) does not affect the door's fire rating. Go larger than 100 square inches and the rating drops by 50 percent — a 90-minute door becomes 45 minutes. That is why the 10" x 10" and 7" x 22" sizes are popular on fire-separation doors: they stay under the limit while still providing visibility.
For non-fire-rated doors in Brampton warehouses and office corridors, there is no practical upper limit. A 22" x 58" full-lite transforms a steel slab into a window door that floods the adjacent space with light.
The Installation Process: Cutting a Solid Steel Door
This is not a DIY job. Cutting into a hollow-metal door requires specific tools, knowledge of the door's internal structure, and an understanding of how the cut affects the door's rigidity. Here is the step-by-step process a qualified installer follows.
Step 1: Layout and Marking
The installer measures and marks the cutout location on the door face. Lite kits are almost always centred horizontally. Vertical placement depends on the lite size — a narrow peek lite sits at eye height (roughly 43 inches from the bottom of the door to the centre of the lite), while a full-height lite starts a few inches from the top rail and ends a few inches above the bottom rail.
The layout uses the order size dimensions, not the glass size. A 22" x 28" lite kit requires a 22" x 28" rectangular hole in the door.
Step 2: Cutting the Opening
The installer uses an angle grinder with a cutting disc or a plasma cutter to open the door face on one side. On a hollow-metal door (which is two steel skins over a cardboard honeycomb or polystyrene core), the second face is cut separately after the core material is removed from the cutout area. Each cut edge gets deburred and filed smooth to prevent injury and ensure the lite frame sits flush.
A plasma cutter gives cleaner edges and is faster on 18-gauge and 16-gauge skins. An angle grinder works on any thickness but requires more cleanup.
Step 3: Internal Reinforcement
This is the step that separates a professional installation from a hack job. A hollow-metal door gets its rigidity from its closed box section. Cutting a large rectangle out of that box weakens it. The installer welds or rivets steel channel reinforcement around the perimeter of the opening — typically at the header (top) and sill (bottom) of the cutout.
For narrow lites (7" x 22" or 8" x 36"), the reinforcement is minimal because the cutout is small relative to the door width. For a full-size 22" x 58" lite, the reinforcement channels are critical to prevent the door from bowing or warping over time. A 16-gauge steel hat channel across the top and bottom of the opening is standard practice.
Step 4: Mounting the Lite Frame
The two-piece vision lite frame goes in from both sides. One half sits against the exterior face, the other against the interior face. Machine screws pass through pre-drilled holes in the frame halves and thread into the opposing half, pulling them tight against the door skin. No welding is required at this stage.
The frame compresses the glazing tape around the glass, creating a weathertight and rattle-free seal. A standard 18-gauge steel lite frame in a satin stainless finish weighs about 3 to 5 pounds depending on size.
Step 5: Glazing
The installer applies glazing tape to both faces of the glass panel, sets the glass into the frame from one side, and then tightens the opposing frame half until the tape compresses evenly. The tape should be visible as a thin, uniform line around the perimeter. If it squeezes out unevenly, the glass is not centred or the frame screws are over-torqued on one side.
For a clean finish, any exposed screw heads get capped or filled. The door edge where the cuts were made gets a touch-up coat of primer and paint to prevent rust — especially relevant in Brampton, where road salt spray reaches loading docks along Highway 410 and Bramalea Road well into April.
Glass Options for Commercial Lite Kits
The glass you specify depends on the door's fire rating, location, and security needs.
1/4-inch clear tempered glass is the default for non-fire-rated doors. It is four times stronger than regular annealed glass and breaks into small, relatively harmless granules if shattered. Cost is low — under $30 for most standard lite sizes.
Fire-rated ceramic glass (SuperLite, Pyrostop, or TGP FireLite) is required for any lite in a fire-rated door assembly. It withstands extreme heat without cracking and blocks radiant heat transfer. Fire-rated ceramic is significantly more expensive — $80 to $300 per panel depending on size and rating duration — but it is non-negotiable when the door sits in a fire separation.
Wired glass (the old-school glass with a diamond wire mesh embedded in it) is still found in many Brampton buildings from the 1980s and 1990s. It holds together when cracked, but is weaker than tempered glass on impact. Ceramic alternatives are the modern standard for new installations and retrofits.
Fire Rating Considerations
Fire-rated doors in commercial buildings are serious business under the Ontario Fire Code. If your steel door carries a 45-minute, 60-minute, or 90-minute fire label, the lite kit installation must comply with NFPA 80 (Standard for Fire Doors and Other Opening Protectives).
Key rules:
- 100 square inches or less of visible glass: no reduction in fire rating. Use a fire-rated lite frame and fire-rated ceramic glass.
- Over 100 square inches: the door's fire rating drops by 50 percent. A 90-minute door becomes 45 minutes. A 60-minute door becomes 30 minutes.
- The lite frame must be listed for the appropriate fire rating. Not all frames carry a fire label. Specify a UL- or ULC-listed assembly.
- Glazing tape must be fire-rated as well. Standard foam tape is not acceptable on a fire-rated assembly.
- Wired glass in 3/4" x 3/4" diamond pattern is still accepted but increasingly replaced by ceramic glass.
After installation, the fire-rated door should be re-labelled to reflect the lite addition. A qualified commercial glass installer can issue documentation confirming the assembly meets code.
Common Mistakes to Avoid
Cutting the hole too large. Measure twice. A cutout that is even 1/4 inch oversized means the lite frame will not clamp properly, and the glazing seal will fail. There is no good fix for an oversized hole short of welding in a patch and starting over.
Skipping reinforcement. A 22" x 28" hole in a hollow-metal door without internal reinforcement will cause the door to flex and eventually bow. The reinforcement channels are not optional — they restore the structural integrity that the cutout removed.
Using non-fire-rated glass in a fire-rated door. This violates NFPA 80 and the Ontario Building Code. In an inspection, the entire door assembly gets flagged, not just the glass. The fix is a full re-glaze with the correct rated glass and frame.
Ignoring the edge treatment. Bare steel edges exposed during the cut will rust. In a Brampton loading dock environment where moisture, salt, and temperature swings are constant through the winter months, untreated edges can show rust within a single season. Prime and paint all cut edges, and consider a rust-inhibiting primer formulated for steel.
What a Lite Kit Retrofit Costs in Brampton (2026)
Pricing depends on the lite size, glass type, and whether the door is fire-rated.
| Component | Typical Cost Range |
|---|---|
| Lite frame (18-gauge steel, standard finish) | $40 – $120 |
| Tempered glass (1/4" clear, standard sizes) | $15 – $45 |
| Fire-rated ceramic glass | $80 – $300 |
| Glazing tape (per roll, enough for 2-3 doors) | $8 – $15 |
| Labour (cut, reinforce, install, paint) | $150 – $350 per door |
| Total per door (non-fire-rated) | $250 – $500 |
| Total per door (fire-rated) | $400 – $800 |
For multi-door projects — common in Bramalea-area industrial buildings where a tenant improvement might touch 10 or 20 corridor doors — volume pricing brings the per-door cost down. It is worth quoting the full scope at once rather than doing doors one at a time.
When to Replace the Door Instead
A lite kit is a retrofit solution. It works well when the existing steel door is structurally sound, hangs square in its frame, and has a clean surface free of deep corrosion. If the door is already bowed, rusted through at the bottom rail, or has a damaged frame, the smarter move is a full door and glass replacement. A new pre-glazed hollow-metal door arrives with the lite cutout, reinforcement, and frame already factory-built, and the fire label is intact from the manufacturer.
Frequently Asked Questions
Can you add a window to an existing solid steel door?
Yes. A steel door lite kit is designed for exactly that. The installer cuts a rectangular opening in the door face, welds or screws in reinforcement channels, and mounts a two-piece vision lite frame around the glass. The result looks factory-installed.
What size lite kit should I choose for a commercial steel door?
It depends on the door's purpose. A narrow 7" x 22" lite works for quick visibility on corridor doors. A half-lite at 22" x 28" suits office entries. A full-lite at 22" x 58" maximizes daylight. If the door is fire-rated, keep the lite under 100 square inches to preserve the full rating.
Does adding a lite kit void a fire-rated steel door?
Not automatically. A lite of 100 square inches or less does not change the fire rating. Anything larger reduces the rating by 50 percent. You must also use fire-rated ceramic glass and a listed lite frame assembly to maintain compliance.
How long does it take to install a lite kit in a steel door?
A single-door retrofit typically takes 2 to 4 hours, including layout, cutting, deburring, frame installation, glazing, and cleanup. If the door can be removed and worked on flat, the job goes faster.
What type of glass goes in a commercial door lite kit?
The most common choice is 1/4-inch clear tempered safety glass. For fire-rated doors, you need fire-rated ceramic glass such as SuperLite or Pyrostop. Wired glass is still found in older installations but is being phased out in favour of ceramic alternatives.
Do I need a permit to add a lite kit to a commercial door in Brampton?
Cutting into a fire-rated door assembly requires the work to comply with the Ontario Building Code and NFPA 80. While a standalone permit is not always required for hardware modifications, the installation must be done by a qualified contractor who can certify the assembly. Check with the City of Brampton building department if your door is part of a fire separation.
If you manage a commercial property in Brampton and your solid steel doors need vision lites — whether for safety, daylight, or a tenant improvement — Installix handles the full process from measurement through glazing. We work with fire-rated and non-fire-rated assemblies across the GTA. Reach out for a quote and we will walk the job with you.