Choosing heavy glass for a custom shower, wine room, partition, or heavy-glass door means making three decisions most homeowners have never made before: thickness, edge finish, and the tempering spec that makes the panel safe for daily use. This guide walks through the spec choices Moffat fabricates in our Northern Colorado shop, what each choice changes, and which thicknesses and edges pair with which applications. It is written for homeowners, designers, and architects spec'ing a luxury project before they request a quote. Moffat has cut, tempered, and finished heavy glass in Northern Colorado since 1921. Custom heavy-glass projects in Northern Colorado typically spec at 3/8" tempered or 1/2" tempered, with edge finishes ranging from flat-polished to ogee, and a tempering process that makes the glass 4 to 5 times stronger than standard annealed glass.
Moffat fabricates heavy glass in two standard thicknesses: 3/8" and 1/2" tempered. Those two thicknesses cover virtually every custom heavy-glass shower enclosure, wine room glass wall, interior partition, and heavy-glass door built to premium-tier spec in Northern Colorado.
3/8" tempered is the minimum thickness for frameless heavy-glass work. It reads as solid and well-built in hand, with no flex or wobble at standard residential panel sizes. It is the right choice for most standard frameless showers, partitions under roughly 80" tall, and wine wall sections where the panel is well-supported by header and floor framing. For most heavy-glass projects in a Northern Colorado home, 3/8" is the default spec.
1/2" tempered is the upgrade. The open edge reads visibly heavier from across the room, the panel feels more substantial in hand, and the spec carries the weight a designer wants when the edge of the glass is meant to be a visual feature. It is the right call for panel heights over roughly 80", wider spans, spa-style walk-in shower layouts where the glass acts as a structural element, large heavy-glass doors, and any project where the design intent is to read as architectural rather than functional.
Panel weight is the practical-design beat behind the thickness decision. A typical heavy-glass panel runs roughly 80 to 130 lb depending on dimensions, and 1/2" panels are heavier than 3/8" panels at the same dimensions. That changes hinge selection and the wall blocking the install team specifies at the on-site measure.
Specialty 3/4" heavy glass appears occasionally for very large structural-glass partitions and certain heavy-door applications. It is rare on residential work, but it is available in-shop on request.
Both 3/8" and 1/2" can be specified in standard clear or in low-iron glass, which reduces the green tint visible on the open edge and reads as truer-to-water clarity. Low-iron is the premium-clarity upgrade designers call for when the glass itself is the design element. Final clarity spec gets locked at the on-site measure when the design intent is decided.
Tempering is the controlled heating and rapid cooling process that turns standard annealed glass into safety-rated tempered glass. Federal code requires tempering on heavy-glass showers, doors, partitions, and overhead glass applications. It is not optional on the work Moffat fabricates; it is what makes the panel legal to install.
The process moves through four beats inside the shop.
Step 1: Cut, edge, and drill before temper. The glass is cut to spec, the edge is worked to the finish the design calls for, and any hinge holes, handle cutouts, or notches are bored into the panel. All of this happens before the panel ever sees the furnace, because no edge work and no drilling can be done after tempering. A tempered panel that needs a hinge hole has to be scrapped and re-fabricated.
Step 2: Heat the panel. The prepped panel goes into the tempering furnace and is heated to roughly 600 to 700°C. The glass moves through the furnace at a controlled pace so the entire panel reaches uniform temperature.
Step 3: Quench with air jets. The hot panel is then rapidly cooled with high-pressure air jets blowing onto both surfaces simultaneously. That rapid quench locks compressive stress into the outer surfaces and tension into the core. The stress profile is what gives tempered glass its strength.
Step 4: The result. Finished tempered glass is 4 to 5 times stronger than annealed glass, and if it ever does break, it shatters into small rounded pebbles rather than long sharp shards. The pebble break pattern is the spec the safety codes are written around.
The codes that require tempering on heavy glass are ANSI Z97.1 and CPSC 16 CFR 1201 at the federal level. Colorado adopts the International Building Code with state amendments, and IBC §2406 covers safety glazing in hazardous locations: showers, glass doors, glass within 24" of a door, and overhead applications.
At Moffat, every heavy-glass panel is tempered in our Northern Colorado shop and inspected before it leaves for installation. That in-shop step is the same step that underpins our lead-time advantage on heavy-glass projects.
The edge is the visible cross-section of the glass. On exposed-edge applications (most frameless showers, wine walls, partitions, and heavy doors), edge choice is the most visible spec decision after thickness. Moffat fabricates five edge finishes on heavy glass.
Flat-Polished Edge. The standard premium edge for most heavy-glass shower enclosures, wine walls, and partitions. The exposed edge is ground flat at a clean 90° profile, then machine-polished to a clear, glassy finish that reads as a precise, modern corner. Available on both 3/8" and 1/2", flat-polished is the default unless the design calls for something else.
Pencil-Polished (Rounded) Edge. The exposed edge is ground to a softly rounded profile (the cross-section reads as the curve of a pencil), then polished to a clear finish. It reads as slightly softer than flat-polished from across the room and is the comfortable choice when the edge sits at hand or eye level. Available on both 3/8" and 1/2", and on specialty 3/4".
Beveled Edge. The edge is ground at a chamfered angle (typically around 45°) for a measured width back from the face of the glass, then polished to a high gloss. The chamfer catches and reflects light from the side as a distinct slim band, which reads as more ornamental than flat or pencil. Best on 3/8" minimum because the chamfer needs enough material depth to read as intentional. Common on heavy-glass shower enclosures with decorative panels and on heavy entry doors.
Ogee Edge. The most ornate edge Moffat fabricates: a double-curve profile (an S-shape combining a convex curve with a concave curve) ground into the exposed edge, then polished. The profile reads as elegant and traditional, and it is the right choice for luxury-tier wine room glass walls, heavy-glass tabletops in formal dining settings, and high-end mirror surrounds. Available only on 1/2" and 3/4" heavy glass, because the S-curve needs the material depth to render properly. Not available on 3/8".
Seamed Edge. The exposed edge is lightly sanded to remove sharp burrs and make the glass safe to handle, but it is not polished. It reads as a utility finish, appropriate for edges fully hidden by hardware clamps, framing, or substrate. Not recommended for any exposed edge. Available on all thicknesses.
All edge work (flat-polish, pencil-polish, bevel, ogee, or seam) is finished on the panel before the panel enters the tempering furnace, because no edge work can be done on tempered glass. Moffat pairs every heavy-glass install with CRL (C.R. Laurence) hardware specified to the thickness and edge of the panel: hinges, clamps, and handles engineered for 3/8" and 1/2" loads.
Thickness and edge spec are decisions made together, not in isolation. Below are the four heavy-glass applications Moffat fabricates and the spec pairings that fit each one.
Frameless Heavy-Glass Shower Enclosures. The most common heavy-glass project. Standard spec is 3/8" tempered with flat-polished or pencil-polished edges. Step up to 1/2" tempered for panel heights over roughly 80", spa-style walk-in layouts where the glass functions as a structural element, or designer specs that want the substantial 1/2" edge to read as a visible feature. Flat-polished is the default edge; pencil-polished gives a softer read at eye level; beveled lands well on ornamental door panels; ogee is reserved for rare specialty showers on 1/2" panels.
Wine Rooms and Wine Walls. Floor-to-ceiling heavy-glass walls separating wine display from living space. Standard spec is 3/8" or 1/2" tempered, depending on panel span, with flat-polished or pencil-polished edges on most installs. Ogee edges are the natural luxury-tier upgrade for formal dining adjacencies and traditional architecture, and they are available only on 1/2" panels. This is the application where edge choice carries the most aesthetic weight: the wine wall is on display, and the edge profile reads from across the room.
Interior Glass Partitions. Heavy-glass walls separating rooms in open-concept layouts, primary-suite glass walls, and study or library partitions. Standard spec is 3/8" tempered with flat-polished edges for most heights. Step up to 1/2" tempered on partitions over roughly 80" tall or when the glass is a load-bearing visual feature in the architecture. Flat-polished is the default; pencil-polished or beveled when the spec wants a softer or more ornamental edge.
Heavy-Glass Doors (Interior and Entry). Frameless or top-rail heavy-glass doors for interior and luxury-entry applications. 1/2" tempered is the typical default because of hinge load and panel size; 3/8" works on shorter, narrower interior doors. Beveled edges are common on heavy-glass doors as a design element catching light along the leading edge, with flat-polished as the conservative-modern alternative. Hardware pairing matters: heavy doors run at the upper end of the panel-weight range (well over 100 lb on the larger sizes), so hinge spec is critical at the on-site measure.
Final thickness and edge spec is confirmed at the on-site measure, where panel dimensions, hardware load, header geometry, and design intent are locked together before any glass is cut.
What thickness of heavy glass do I need for a custom shower, wine room, or partition?
Most standard residential heavy-glass work specs at 3/8" tempered, and 1/2" tempered is the upgrade for panels over roughly 80" tall, wider spans, walk-in spa shower layouts, and large heavy-glass doors. The same logic applies to wine rooms and partitions: 3/8" for standard heights, 1/2" when the panel is taller, wider, or meant to read as a structural design element. Final thickness is confirmed at the on-site measure where panel dimensions, hardware load, and design intent are locked together.
How is tempered glass actually made, and why does it matter for heavy glass?
Tempered glass is safety glass produced by controlled heating and rapid cooling. We heat each panel to roughly 600 to 700°C, then quench it with high-pressure air jets, which makes it 4 to 5 times stronger than annealed and gives it the small-pebble break pattern required by ANSI Z97.1 and CPSC 16 CFR 1201. We temper in-shop on every heavy-glass project.
What edge finishes can Moffat fabricate on heavy glass?
Moffat fabricates five edge finishes on heavy glass: flat-polished, pencil-polished, beveled, ogee, and seamed. Flat-polished and pencil-polished are the most common pairings for showers, wine walls, and partitions; beveled and ogee are the luxury-tier ornamental choices on heavy-glass doors and formal wine room walls. Final edge spec is confirmed at quote and on-site measure.
Can I get an ogee or beveled edge on 3/8" heavy glass?
Beveled, yes: 3/8" is the minimum thickness for a beveled edge. Ogee, no: the ogee S-curve profile requires 1/2" or 3/4" heavy glass because the ornamental cross-section needs the material depth to render properly. We will confirm edge and thickness pairing at the on-site measure so the spec is right before fabrication begins.
What's the difference between flat-polished, pencil-polished, and seamed edges?
Flat-polished is a clean 90° edge ground flat and polished glossy. Pencil-polished is the same polish-finish on a softly rounded edge profile. Seamed is a lightly sanded utility edge not for exposed glass: it is specified only when the edge will be hidden by hardware or framing. Flat or pencil for any visible edge; seamed only where it is out of sight.
Thickness, edge finish, and tempering are the three decisions that shape every custom heavy-glass project, and the right choice depends on the panel, the application, and the design intent behind the project. Moffat fabricates and tempers 3/8" and 1/2" heavy glass with flat-polished, pencil-polished, beveled, ogee, or seamed edges in our Northern Colorado shop, and we walk every spec at the on-site measure before any glass is cut. Over a century of Northern Colorado glass craftsmanship, three locations serving Larimer and Weld County (Evans, Loveland, and Fort Collins), and in-shop fabrication on every heavy-glass project. Request a quote with your spec, or give us a call to schedule an on-site measure.
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