Glass work in a home covers more ground than most homeowners realize — shower enclosures, frameless glass doors, mirrors, glass railings, glass balustrades, interior glass partitions, and specialty glass applications like wine cellar doors and barn door glass inserts. Each application has different structural requirements, different safety glass specifications, and different installation complexity.
Glass is also a trade where safety standards are both specific and consequential. Tempered and laminated safety glass requirements exist for a reason — a shower enclosure failure or a railing glass panel failure is not a cosmetic problem. Understanding which applications require which safety glass certifications, and verifying that the contractor is installing to those standards, is the most protective thing a homeowner can do when hiring for glass work.
“The safety glass question is where I find out immediately whether I’m dealing with a professional operation or a cut-rate one. Every shower enclosure, every glass railing, every piece of glass in a hazardous location requires safety glazing — either tempered or laminated, with the appropriate SGCC certification mark on the glass itself. A contractor who can’t show you that mark on the installed glass or confirm it’s in the specification is cutting corners on the most important safety requirement in this trade.”
— Giannis from GAK Windows and Doors, window and door specialist with over 15 years of experience providing residential and commercial installation and replacement services across Toronto, focused on energy-efficient solutions, quality craftsmanship, and reliable customer service
Table of Contents
Before You Call Anyone
What type of glass work do you need?
Shower enclosures: Frameless, semi-frameless, or framed glass panels enclosing a shower. Frameless enclosures use heavier glass (typically 3/8″ or 1/2″ thick) and minimal metal hardware. Semi-frameless use lighter glass with metal channel framing at some edges. Framed enclosures have full metal frames.
Mirrors: Bathroom vanity mirrors, full-length mirrors, decorative mirrors, custom-shaped or custom-sized mirrors, mirror walls.
Glass railings: Glass panels used as the infill in stair railings or deck/balcony railings, replacing traditional balusters. Can be framed (glass in a metal channel system) or frameless (standoff-mounted glass with no top or bottom rail).
Interior glass partitions: Fixed or sliding glass panels used to separate interior spaces — office glass walls, glass room dividers, glass sliding barn doors.
Specialty glass: Wine cellar glass doors, glass shelving, glass backsplashes, decorative leaded or frosted glass.
Is this a structural or non-structural application?
Glass railings and balustrades that people could lean or fall against are structural applications — the glass itself is a fall-prevention barrier. This distinction determines the glass thickness, type, and installation requirements. Non-structural applications (mirrors, shower enclosures, decorative glass) have different but still specific requirements.
Questions to Ask Before Hiring
Is your company a registered business with insurance and workers’ compensation coverage?
Glass installation involves heavy materials, cutting tools, and in some cases elevated work (balcony railings, staircase glass). Liability insurance is essential. Workers’ compensation coverage covers workers if injured.
Ask for a certificate of insurance and workers’ compensation coverage Clearance Certificate.
Are your installers certified glaziers?
Glazier is a Red Seal trade. A certified glazier has completed a formal apprenticeship and passed the inter-regional examination. For structural applications — glass railings, large frameless shower enclosures — certified glazier expertise matters.
What a good answer looks like: Red Seal glazier certification confirmed, or a described apprenticeship background.
How long have you been doing this type of installation?
Experience with the specific application matters. A company that primarily does commercial window glazing may not have the same experience with residential frameless shower enclosures or glass railing systems as a specialist residential glass contractor. Ask specifically how many installations of your project type they’ve completed.
Questions About Safety Glass
What type of safety glass will be used, and does it meet the applicable building code requirements?
This is the most important technical question for any glass installation where a human could impact the glass or where glass failure could cause injury. The applicable building code (OBC) Section 9 specifies which locations require safety glazing — and “safety glazing” means glass that, when it breaks, breaks in a way that minimizes injury risk.
Tempered glass: Heated and rapidly cooled to create a glass that is approximately four times stronger than standard glass and that, when it breaks, shatters into small, relatively harmless granules rather than large dangerous shards. Required in most hazardous glazing locations.
Laminated glass: Two or more glass layers bonded with an interlayer (typically polyvinyl butyral — PVB). When broken, the interlayer holds the fragments together, preventing them from falling. Used in overhead glazing, glass floors, and applications where broken glass must remain in place.
Where safety glazing is required by OBC: Shower and tub enclosures, glass adjacent to doors, glass within 900mm of a door, glass railings and balustrades, glass in any location below 900mm from the floor in commercial applications, and other hazardous locations.
Ask specifically what glass type is being specified and confirm it meets OBC requirements for the application.
Will the glass bear a safety glazing certification mark?
Certified safety glass bears a permanent mark — etched, ceramic-fused, or sandblasted into the glass — from a recognized safety glazing certification organization. In North America, the Safety Glazing Certification Council (SGCC) is the primary certification body.
The mark includes the manufacturer’s name, the SGCC logo, and the applicable ANSI/safety standard.
Ask specifically: Will the installed glass have a visible safety glazing certification mark?
What a good answer looks like: Confirmed SGCC certification mark on all safety glazing, with the contractor able to show you what to look for in the installed product.
For more: Questions to Ask a Glass Contractor About Safety Glass Standards
Questions About Shower Enclosures
What glass thickness is being used for the shower enclosure?
Glass thickness for shower enclosures determines both strength and rigidity:
3/8″ (10mm) tempered glass: The minimum appropriate thickness for most frameless shower enclosures. Adequate for standard panel sizes.
1/2″ (12mm) tempered glass: The preferred thickness for larger panels, taller enclosures, and high-end installations. Significantly more rigid and substantial-feeling than 3/8″.
Framed and semi-frameless enclosures can use thinner glass (typically 1/4″ or 5/16″) because the frame provides structural support.
Ask what thickness is being proposed and why it’s appropriate for your enclosure dimensions.
What hardware finish is being used, and is it coordinated with existing fixtures?
Shower enclosure hardware — hinges, handles, towel bars, wall mounts — comes in a range of finishes: chrome, brushed nickel, oil-rubbed bronze, matte black, polished gold. The finish should coordinate with existing bathroom fixtures (faucets, towel bars, shower head).
Ask specifically what hardware finish is being proposed and whether it matches the existing fixtures.
For more: Questions to Ask a Glass Contractor About Shower Enclosures
Questions About Glass Railings
What glass and system is being proposed for the railing?
Glass railings are structural — they must resist the lateral forces of people leaning against them, per OBC requirements. Ask specifically:
Glass type: Tempered or laminated tempered glass. OBC typically requires laminated glass or laminated tempered glass for overhead and walking surface applications; tempered is commonly accepted for vertical railing panels.
Glass thickness: Typically 1/2″ (12mm) for most residential railing applications. Some systems require thicker glass.
System type: Channel-mounted (glass sits in a metal channel top and bottom), standoff-mounted (glass is drilled and attached with through-bolts), or frameless clamp systems. Each has different structural behavior and appearance.
Engineering: Glass railing systems used on decks or balconies in many regions typically require a building permit, and the glass panel design may require engineering sign-off.
For more: Questions to Ask a Glass Contractor About Glass Railings
Questions About Mirrors
What type of mirror backing is being used?
Mirror quality — particularly in bathroom applications — depends significantly on the backing material:
Copper-free mirrors: Modern mirrors with a tin-based or alternative backing that is more moisture-resistant than traditional copper-backed mirrors. The appropriate specification for bathroom applications.
Standard (copper-backed) mirrors: Susceptible to moisture infiltration at the edges, causing the characteristic dark edge deterioration (“black edge” or “foxing”) seen in older bathroom mirrors. Less appropriate for humid bathroom environments.
Ask specifically whether copper-free mirror glass is being used for any bathroom installation.
How will the mirror be mounted?
Mirror mounting methods significantly affect safety and longevity:
J-channel and clips: The mirror sits in a bottom J-channel with clips along the top and sides. The mirror is not bonded to the wall. Can be removed without damaging the wall.
Adhesive (mirror mastic): Mirror-specific adhesive applied to the back bonds the mirror to the wall. Strong but permanent and can damage drywall on removal. Requires mirror-specific adhesive — standard construction adhesive can damage the mirror backing.
French cleat: A horizontal mounting rail at the top of the mirror. Allows easy removal and reinstallation.
For large or heavy mirrors, ask about the attachment method and whether it’s appropriate for the wall type (drywall, tile, plaster) and mirror weight.
Red Flags to Watch For
Unable to confirm that safety glass will be used in hazardous locations. Any contractor who can’t confirm the glass type and certification for a shower enclosure, glass railing, or other hazardous location is either uninformed or planning to use non-safety glass. Both are serious problems.
No SGCC certification mark mentioned. Safety glass that isn’t certified and marked is not verifiably safety glass. The mark on the glass itself is the only reliable confirmation.
Standard construction adhesive proposed for mirror installation. Mirror mastic (mirror-specific adhesive) is required for mirror installation — standard adhesives damage the mirror backing. A contractor who doesn’t distinguish between the two lacks product knowledge.
Glass railing system proposed without mention of permits or engineering. Structural glass railing systems on decks or balconies typically require building permits in many regions, and the structural design may require engineering review.
Very low price for frameless shower enclosure. Frameless enclosures require thicker glass, more substantial hardware, and more precise installation than framed enclosures. A dramatically low price usually reflects thinner glass, lower-quality hardware, or less experienced installation.
For a full guide: Red Flags When Hiring a Glass Contractor
Before They Start: A Quick Checklist
- Business registration and insurance verified
- Workers’ compensation coverage clearance verified
- Glazier certification confirmed for structural applications
- Safety glass type (tempered/laminated) confirmed for all hazardous locations
- SGCC certification mark confirmed as part of specification
- Glass thickness confirmed and appropriate for application
- Hardware finish coordinated with existing fixtures
- Permits confirmed for glass railings or structural applications
- Written quote with full specifications
- Payment schedule agreed
Related Questions
- Questions to Ask a Glass Contractor About Safety Glass Standards
- Questions to Ask a Glass Contractor About Shower Enclosures
- Questions to Ask a Glass Contractor About Glass Railings
- How Much Does a Glass Shower Enclosure Cost ?
- Red Flags When Hiring a Glass Contractor
- What to Do If a Glass Contractor Does Bad Work
Have a question we didn’t cover? Submit it below.