Toughened and laminated glass are both safety glass, but they keep you safe in opposite ways. Toughened glass is hard to break and, when it does break, it falls apart into small, blunt pieces. Laminated glass may crack more easily, but the pieces stay stuck to a plastic layer and the panel stays in the opening. Choosing between them is mostly a question of which way of breaking is safer where the glass is going.
Side by side
| Toughened | Laminated | |
|---|---|---|
| How it is made | One pane, heated and cooled quickly | Two or more panes bonded with an interlayer |
| Strength | Commonly quoted as four to five times ordinary glass of the same thickness | Depends on the panes used; toughened panes can be laminated too |
| When it breaks | Small pieces, the panel falls out | Pieces stay on the interlayer, the panel stays in |
| Cut after making? | No | Yes if made from ordinary panes, no if made from toughened panes |
| Noise | Like ordinary glass | Better, especially with an acoustic interlayer |
| Security | Once broken, the opening is clear | Slows down a break-in; security grades are available |
| UV | Lets most UV through | A PVB interlayer blocks most UV, which helps reduce fading |
| Product standard | BS EN 12150 | BS EN 14449 |
What is toughened glass?
Toughened glass, also called tempered glass, is ordinary float glass that has been cut to size, edge worked and drilled, then heated in a furnace and cooled very quickly with jets of air. The outer surfaces end up in compression and the middle in tension. A crack has to get through that compressed outer layer before it can grow, which is why the glass is so much stronger. It is also why it cannot be cut afterwards: breaking the outer layer releases the tension and the whole panel shatters. Our guide on how toughened glass is made goes through each step.
What is laminated glass?
Laminated glass is two or more panes bonded together with a plastic interlayer. The panes are washed and laid up in a clean room with the interlayer between them, pressed to remove air, then finished under heat and pressure in an autoclave. The bond is permanent and clear. When the glass breaks, the pieces stay on the interlayer, so the panel still keeps out the weather and people.
Laminated glass is usually described by its build-up. 6.4 mm laminated, for example, is two 3 mm panes with a 0.38 mm interlayer, and 8.8 mm is two 4 mm panes with a 0.76 mm interlayer. Thicker panes and thicker interlayers are used for larger panels, roofs and balustrades.
Choosing an interlayer
| Interlayer | Good for |
|---|---|
| PVB | The everyday choice for safety and security glazing. Acoustic grades also help reduce noise. |
| EVA | Decorative laminates, such as glass with fabric or mesh inside, and places where edges may be exposed to moisture. |
| Ionoplast (for example SentryGlas) | A stiff, strong interlayer used for demanding work such as balustrades and structural glass. |
Toughened laminated: both at once
The two are not opposites. Toughened panes can be laminated together, which gives the strength of toughened glass and a panel that stays in place when broken. This is the usual build-up for glass balustrades, glass floors and stairs (with an engineer's design), and many roof panels. Because each pane is toughened first, toughened laminated glass has to be ordered at the exact finished size, with every hole and notch already in place.
The usual choice by job
| Where | Usually | Why |
|---|---|---|
| Shower screens | Toughened | Strong, and breaks into small pieces if it does break |
| Table tops and shelves | Toughened | Takes knocks and heat from hot dishes better |
| Kitchen splashbacks | Toughened | Behind a hob it has to cope with heat |
| Doors and glass beside doors | Toughened or laminated safety glass | A UK critical location (see below) |
| Balustrades | Toughened laminated | Must keep protecting the drop if one pane breaks |
| Roofs, canopies and rooflights | Laminated, often as the inner pane of an insulated unit | Broken glass must not fall on people below |
| Shopfronts and ground floor windows | Laminated or toughened laminated | Slows down a break-in |
| Windows on a noisy road | Laminated with an acoustic interlayer | The interlayer damps sound |
This is a starting point, not a specification. Your builder, architect or engineer should confirm what your project requires, especially for balustrades and anything structural.
Where UK rules ask for safety glass
In England, Approved Document K sets out "critical locations" where glass must break safely or resist impact. In broad terms these are glass in doors and in side panels close to doors up to 1500 mm above the floor, and glass in walls and partitions below 800 mm from the floor. Both toughened and laminated glass can be classed as safety glass for these places when they meet the impact test in BS EN 12600. Your builder or building control can confirm what applies to your project.
Security and noise
For security, laminated glass is the stronger choice, because a broken pane still has to be cut or battered through. Security laminates are graded under BS EN 356, from P1A upwards; ask for a grade if your insurer or specifier names one. For noise, laminated glass with an acoustic PVB interlayer performs better than toughened or ordinary glass of a similar thickness, and works well as one pane of a double glazed unit.
Cost and lead time
For the same size, laminated glass usually costs more than toughened glass because there are more panes and more steps, and toughened laminated costs more again. Made to size glass of any type is cut and processed for your order. Send us your sizes and we will price the options side by side so you can compare.
Questions we are asked
Which is stronger, toughened or laminated?
Against an impact, toughened glass of the same thickness is stronger. Laminated glass is safer after breaking because it stays in place. Toughened laminated gives both.
Is laminated glass the same as safety glass?
Laminated glass is one kind of safety glass when it passes the impact test in BS EN 12600. Toughened glass is the other common kind.
Is tempered glass the same as toughened glass?
Yes. Tempered is the more common word in America; toughened is more common in the UK. The product is the same.
How can I tell which glass I have?
Look in a corner for a mark. Toughened glass is usually marked with BS EN 12150, and laminated safety glass with BS EN 14449 or an impact class from BS EN 12600. If there is no mark, treat the glass as unknown and ask a glazier.
Can laminated glass be cut on site?
Laminated glass made from ordinary panes can be cut by a glazier with the right tools. Toughened laminated glass cannot be cut at all.
Which glass for a glass roof?
Overhead glass should stay in place if it breaks, so the pane facing the room is normally laminated. In an insulated roof unit the outer pane is often toughened and the inner pane laminated.
Still not sure?
Tell us where the glass is going, its size and how it will be fixed. We make both types in our own factory, so we have no reason to steer you to one over the other.
Toughened glass and laminated glass are priced to your sizes. Send them over and we reply with a written price.