How to choose the right glass thickness for storefronts

The first question we get on most storefront quotes is, “what thickness do you recommend?”

The honest answer is, “it depends on five things you have not told me yet, so let us walk through them.” There is no single right thickness for a storefront. The right thickness is whatever balances safety, code compliance, panel size, hurricane exposure, and budget for your specific project.

Here is the framework we use to make that call.

The available thicknesses

For commercial storefronts in Jamaica, the practical thickness options are quarter inch, three eighths inch, half inch, and (less often) five eighths or three quarters inch for very large panels or specialty applications.

Quarter inch is the base spec. Stronger than residential glass, suitable for moderate panel sizes, the lowest cost per square foot.

Three eighths inch is the workhorse thickness for typical retail storefronts. Roughly 50 percent stronger than quarter inch, suitable for larger panels and busier doors, mid-range cost.

Half inch is the premium spec. Used on door panels of any size, on fixed panels above six feet wide, and on any panel that needs to take impact. Roughly double the cost per square foot of quarter inch.

Five eighths and three quarters inch are specialty thicknesses for very large panels (over ten feet tall or wide), curtain-wall applications, or high-security installations. Rare on standard retail storefronts.

Every thickness above is available as tempered safety glass (the standard) and as laminated safety glass (for security or specific code requirements). Laminated is roughly 25 to 40 percent more expensive than tempered at the same thickness.

The panel size rule

The single biggest factor in choosing glass thickness is the size of the individual panel. Larger panels need thicker glass to resist deflection (bowing under wind or impact loads) and to maintain structural integrity over time.

A rough working rule that holds for most Jamaican commercial storefronts.

Panels up to about 18 square feet (for example, 3 by 6 feet): quarter inch is structurally fine.

Panels between 18 and 36 square feet (for example, 4 by 9 feet): three eighths inch is the right call.

Panels between 36 and 60 square feet (for example, 6 by 10 feet): half inch.

Panels over 60 square feet: half inch with structural review, or five eighths inch.

This is a working rule rather than a code requirement. The actual code calculation depends on wind load, mounting type, and edge support. A qualified glazier or structural engineer should sign off on anything close to the boundary.

Modern building with a glass facade showing the kind of large-panel storefront that needs careful thickness specification

The door panel rule

Door panels are a special case. They take repeated impact (hands, bags, kicks, the occasional shoulder), they are hinged on one edge so the loads concentrate at the pivot, and they are usually the most visible glass on the storefront.

Our standard recommendation for storefront door panels.

For residential or light retail doors with low daily traffic, three eighths inch tempered is the minimum.

For typical retail and commercial doors, half inch tempered is the right answer almost regardless of door size. The extra thickness reduces flex at the pivot, holds the closer adjustment longer, and gives a more solid feel that customers notice.

For high-traffic commercial doors (gyms, busy retail, hotel lobbies), half inch tempered, or in some cases half inch laminated for the added security.

We rarely spec doors in quarter inch glass on commercial projects. The cost saving is small and the failure rate is meaningfully higher.

Hurricane and impact considerations

Jamaican coastal projects within the hurricane wind zone often need to meet impact-rated specifications. The rules vary by parish and insurance requirements, but the general framework is straightforward.

For wind-rated only (no impact requirement), half inch tempered handles most residential and small-commercial cases. Larger storefronts need engineering calculation.

For impact-rated, laminated glass is required, usually half inch or thicker, with a specific interlayer rated for missile impact testing. This is significantly more expensive (typically 60 to 100 percent more than standard tempered at the same thickness) but is the only way to meet impact code in coastal zones.

If your project is in a coastal parish, raise the impact question with your installer at quote stage. Retrofitting impact glazing later is much more expensive than specifying it correctly from the start.

Safety-glazing code

Jamaica’s adopted building code (based on the 2018 International Building Code with national amendments) requires safety glazing in most storefront locations regardless of thickness. The specific code rules.

Any panel in a door, or within 24 inches of a door edge, must be tempered or laminated safety glass.

Any panel within 60 inches of the floor that is part of an opening larger than 9 square feet must be safety glass.

Any panel that could be mistaken for a passageway (full-height glass near foot traffic) must be safety glass.

These are minimums. In practice, every panel in a commercial storefront should be tempered, which is what we always spec.

Energy and acoustic considerations

If your storefront is on an air-conditioned interior space, a few additional choices are worth considering.

Low-E coatings reduce heat gain through the glass and can cut cooling costs significantly. They add about 20 to 35 percent to glass cost. Worth it for storefronts on south or west-facing facades.

Insulated glass units (IGUs, with two panes and a sealed air gap) further reduce heat transfer. They add about 60 to 90 percent to glass cost. Worth it on high-energy-use commercial spaces.

Laminated glass with a thicker interlayer reduces sound transmission. Useful for storefronts on busy roads where street noise affects the interior environment.

Each of these affects total glass thickness. An IGU with two quarter-inch panes and a half-inch air gap is effectively one inch of total assembly thickness in the frame, which the framing has to be specced to accept.

What to ask your installer

When you are getting a storefront quote, ask specifically.

What thickness are you specifying for each panel position, and why?

What is the safety-glazing standard for each panel? Tempered or laminated?

Is this spec appropriate for the panel size we have agreed?

Is any panel close to the threshold where the next thickness up would be safer?

Is impact rating required for our location, and if so, what is the spec?

What is the cost difference between the recommended spec and the next thickness up?

A serious installer will answer all of these without hesitation. An installer who answers “the usual thickness” or who cannot tell you why a specific thickness is right is not engaging with the actual engineering.

A simple summary

For most Jamaican commercial storefronts, the realistic default spec is:

Fixed panels under 18 square feet: quarter inch tempered.

Fixed panels 18 to 36 square feet: three eighths inch tempered.

Fixed panels 36 to 60 square feet: half inch tempered.

Door panels of any size: half inch tempered.

Any panel in a coastal impact zone: half inch laminated with appropriate impact rating.

Any panel above 60 square feet: half inch or five eighths inch with engineering review.

These defaults cover about 90 percent of the projects we install. The other 10 percent have unusual sizes, locations, or use cases that warrant a custom spec.

For background on the tempering process that produces safety glass, see the Wikipedia entry on tempered glass.

The next step

If you are planning a storefront and want a quote that names the glass thickness for each panel position in writing, with the reasoning behind each choice, our team is happy to provide it. We engage with the actual engineering rather than defaulting to a single thickness across the whole install.

Request a quote, browse our commercial work, or get in touch to talk through your project.