Glass + Glazing Types Reference

Why this matters

Service techs handle windows, glass storm doors, shower doors, glass panels in garage doors, mirrors. Wrong glass type = breaks under stress + safety hazard. Replacing tempered with annealed = code violation. The tech who knows glass types serves customers safely + correctly. This is the field card.

Glass types

Annealed (float) glass: standard pane; cooled slowly; breaks into sharp shards. Used: most picture windows, mirror, non-impact furniture.

Heat-strengthened: 2x stronger than annealed; breaks into larger pieces (not safety glass per code). Specific applications.

Tempered: 4x stronger; breaks into small dice (safety glass). REQUIRED in: doors, side panels of doors, bath/shower, low-elevation windows (within 24" of door, within 18" of floor, larger area within 60" of floor adjacent to floor surface), pool fences.

Laminated: two glass panes bonded with plastic interlayer (PVB OR EVA). Resists shattering. Used: car windshields, hurricane impact, school + commercial security, sound reduction.

Insulated glass unit (IGU): 2 OR 3 panes spaced apart with sealed edge; argon OR krypton gas fill; Low-E coating. Standard residential window construction since 1990s.

Wired glass: wire mesh embedded; fire-rated. Restricted in pedestrian access areas (now considered hazardous).

Patterned (textured): privacy glass with patterns (frosted, beveled, hammered). Bathroom, decorative.

Mirrored: aluminum OR silver coating on glass back. Various silver + tin protective coatings.

Glass thickness

1/8" (3 mm): lightweight; mirror backing, picture frames, small windows.

3/16" (5 mm): residential single-pane windows, storm windows.

1/4" (6 mm): standard residential; full-pane windows; storm doors.

3/8" (10 mm): heavier impact; shower glass; doors.

1/2" (12 mm): structural glass railing; tabletop; heavy doors.

3/4" (19 mm): large all-glass doors; heavy commercial.

Tempered glass (code requirements)

Per IBC 2406 + IRC R308. Required where breakage hazards humans: all glass doors (entry, patio, French); side panels within 24" of door + within 60" of floor; windows within 24" of door + 60" of floor; near-floor windows (sill < 18", area > 9 sq ft, within 36" of walking surface); shower/bath/sauna glass; pool/spa fence; stair guard panels; skylights (laminated OR tempered with interlayer). Marking required: etched corner with manufacturer + temper status. Don't drill OR cut tempered (shatters); cuts/holes done before tempering.

Laminated glass

Hurricane + impact-rated: required Florida + Gulf Coast coastal zones.

Sound reduction: STC rating 30 - 40 (vs ~ 24 single pane).

Security: resists smash-and-grab; takes time to break through.

UV protection: PVB blocks 99% of UV (protects fabric, art).

Self-supporting after break: shards stick to interlayer.

Insulated glass (IGU) construction

Two panes: typical residential window.

Triple-pane: cold climates; better R-value.

Spacer: aluminum (older) OR low-conductivity foam / butyl. Aluminum spacer = "warm edge" reduces edge condensation.

Gas fill: argon (most common; cheap; effective); krypton (more efficient + expensive).

Low-E coating: low-emissivity metallic film on inside surface; reflects heat back. Different coatings for cold (heat-retention) vs hot (heat-reflecting) climates.

Lifespan: 15 - 25 yr typical; failure = fogging between panes.

Replacement: IGU only (not whole window) for failed unit; common service.

Mirror

1st surface (front silvered): silvering on front of glass; specialty.

2nd surface (back silvered): standard; reflective coating on back; protected by paint.

Mirror coating types:

• Silver: highest reflectivity; oxidizes if exposed (sealed by paint)
• Aluminum: slightly less reflective; more affordable
• Various copper + tin protective layers

Bathroom mirrors: heavier paint + moisture-resistant backing.

Antique mirror: intentional aging effect; not for high-traffic.

Glass cutting

Score + snap: score with carbide wheel, snap along score. Annealed glass only.

Wet diamond saw: thick glass, intricate cuts.

Tile saw with diamond blade: clean cuts.

Don't cut tempered: shatters.

Edge polishing: diamond wheel; required for safety + clean look on exposed edges.

Glass safety + handling

Lift with suction cups: large panes.

Gloves: prevent edge cuts; sometimes specific glass-handling gloves.

Eye protection: glass particles in cutting + handling.

Don't lay glass flat OR carry parallel to ground: shatters from twisting OR impact.

Carry on edge with pane vertical.

Don't store leaning: stress can break.

Window glazing systems

Vinyl (PVC) window: low-cost; common residential 2000s+.

Aluminum window: older commercial + apartment buildings.

Wood window: traditional; high-maintenance.

Fiberglass / composite: high-end; lower expansion + better insulation.

Aluminum-clad wood: combines wood interior with aluminum exterior.

Window U-factor + SHGC

U-factor: 1/R-value; lower = better insulation.

SHGC (Solar Heat Gain Coefficient): 0 - 1; lower = blocks more solar heat.

ENERGY STAR + IECC requirements: vary by climate zone.

Typical residential:

• North: U 0.25 - 0.30, SHGC 0.30 - 0.40
• Central: U 0.30 - 0.35
• South: U 0.40 - 0.50, SHGC 0.25 - 0.30

Replacement scenarios

Failed IGU (foggy / condensation between panes):

• Order replacement IGU (matches frame size)
• Remove glazing tape / stops
• Replace IGU
• Re-glaze with new tape / stops

Broken pane (single pane window):

• Measure exact pane size
• Order glass (annealed OR tempered per code)
• Remove broken; clean glazing area
• Install + putty / glazing point

Storm door glass: tempered required by code.

Shower door: tempered always (frameless = thicker; framed = standard).

Garage door window: tempered if within 24" of edge + < 60" from floor.

Sealing + glazing compounds

Linseed oil putty (traditional): for wood-sash windows.

Acrylic latex caulk: most modern install.

Silicone: high-flexibility; shower + outdoor.

Polyurethane: high-strength; commercial.

Polysulfide: high-end IGU manufacturing.

Butyl tape: behind window frame + IGU.

Common glass + glazing mistakes

Using annealed where tempered required (code violation; safety hazard). Damaging IGU edge seal during install (premature failure). Skipping spacer in IGU (panes contact + crack). Improperly applied glazing (leaks + fogging). Wrong U-factor for climate (energy code violation). Skipping low-E coating (high heat gain). No SHGC for hot climate (cooling cost spike).

Customer questions

Code compliance: where is tempered required + why.

Energy efficiency: U + SHGC for new windows.

References

• IBC + IRC R308 (Glazing in Hazardous Locations)
• ASTM C1036 (annealed glass), C1048 (heat-treated glass)
• ANSI Z97.1 (safety glazing)
• ENERGY STAR + AAMA window standards
• Manuall internal: Common Codes Overview, PPE Selection by Task