Toughened glass vs laminated glass: how to specify correctly
A guide to the right safety glass for your project
Selecting the correct type of glass is critical in architectural and structural glazing. The decision between choosing toughened glass vs laminated glass is not simply a matter of cost or aesthetics – it directly affects safety, security, compliance, and long-term performance. While both toughened and laminated glass fall under the category of safety glazing, they serve distinct functions and are suitable for very different applications.
At Cotswold Windows, we specialise in supplying and advising on architectural glazing systems for high-spec residential and commercial projects. Our expertise allows us to tailor specifications precisely to project requirements, to ensure the right window safety glazing is used in the right location, every time.
Understanding the differences: toughened glass vs laminated glass
1. Toughened glass (tempered glass)
Toughened glass, also known as tempered glass, is manufactured by heating float glass (glass in its purist form) to high temperatures and then cooling it rapidly to create surface tension. This process strengthens the glass by up to five times compared to untreated float glass. If broken, it shatters into small, relatively blunt fragments that are less likely to cause injury than the sharp-edged shards from broken float glass.
Why use toughened tempered glass:
- Breaks into small, blunt fragments on impact, reducing the risk of injury.
- Mandatory in doors, side panels, internal partitions, and windows above 800mm from floor level.
- Specified where impact resistance and cost-effectiveness are key considerations.
- Typically used where security resistance is not critical.
Can you cut toughened glass?
The answer is that once it has gone through the heat process, toughened tempered glass cannot be cut to size. Toughened glass must be manufactured to the exact dimensions which is why we always recommend working with a glazing specialist who can help to make early design decisions.
2. Laminated glass
Laminated glass consists of two or more sheets of glass bonded together with an interlayer, typically made of PVB (polyvinyl butyral), EVA (ethylene-vinyl acetate), or SGP (SentryGlas Plus). If broken, the interlayer holds the shards in place, maintaining a physical barrier. This makes laminated glass ideal for security-critical applications and fall from height protection.
Laminated glass also reduces noise transmission, blocks UV rays, and can be specified with smart technologies like switchable LCD privacy glass or integrated heating elements, which are increasingly popular in bespoke projects.
Why use laminated glass:
- Provides exceptional impact resistance, making it ideal for critical safety areas.
- Delivers security protection against break-ins, complying with Approved Document Q.
- Offers additional benefits such as acoustic insulation, UV filtration, and multi-layer strength for structural applications.
Specialist laminated glass options:
- SGP-laminated glass offers exceptional strength and rigidity, enabling the use of thinner glazing profiles. This is particularly good for applications like frameless balustrades, walk-on rooflights, and cantilevered roof glazing.
- Decorative laminated glass includes coloured interlayers, frosted finishes, or patterned textures.
- Smart laminated glass can include switchable LCD layers (privacy-on-demand) or blackout glass that adjusts for light and privacy control.
- Heated laminated glass has near-invisible wires in the interlayer to warm the pane, and is often used in cold climates or high-spec pool environments to eliminate condensation.
In some scenarios where extra strength, safety or security is required, a combination of both toughened and laminated glass can be used.
Safety glazing building regulations
1. Part K – Protection from Impact
Part K of the Building Regulations mandates the use of safety glass in areas with a high risk of human impact. This includes doors and side panels up to 1500mm high, and glazing that sits below 800mm from floor level. In these areas, either toughened or laminated glass can be used, depending on the additional demands of the installation.
2. Fall From Height considerations
In locations where there is a risk of falling from one level to another – such as balconies, roof terraces, mezzanine floors, or upper-level windows – glass must resist a range of barrier loads and remain in place even if cracked. This is a critical safety requirement, particularly in balustrade systems without handrails or in frameless glass guards. Laminated glass is mandatory in these applications, often incorporating SGP for additional assurance and compliance.
3. Part Q – Security of Dwellings
Part Q focuses on ensuring resistance to forced entry in all accessible points of new residential buildings. Glazing in doors, ground-floor windows, and roof-accessible areas must be robust and fitted with security-rated components.
Cotswold Windows ensures products meet enhanced security and burglar resistance standards such as PAS 24 and European standard EN 1627 (EN 1627 defines six resistance classes, ranging from RC1 to RC6, with each class representing a different level of security. RC2 specifically addresses the protection level required for building security against occasional burglars using basic tools.)
4. Swimming pool environments
Another highly regulated area is glazing in and around swimming pools, where slip hazards increase the risk of impact. Building guidelines stipulate that laminated glass must be used within two metres of the pool edge, ensuring that a fall against the glass will not result in dangerous shattering or collapse. You can read more in our Guide to Swimming Pool Glazing.
5. Parts L & O – U-value calculations
Glazing also contributes to Part L (conservation of fuel and power) and Part O (overheating mitigation) building regulation considerations. Glass units must meet required U-values for insulation, and in some cases, g-values for solar control and toughened and laminated glass plays a part in meeting these requirements. To learn more, read our blog, Know Your Numbers: a Guide to Calculating U-values in Windows.
How to specify safety glass correctly
At Cotswold Windows, we assess each project’s safety glazing requirements by factoring in its location and environmental exposure, the structural load requirements, the risk factors for impact, fall, or intrusion as well as the desired finishes, privacy needs, and decorative effects.
We use mechanical strength calculators and wind load simulations to validate every glass unit before sign-off, ensuring each product meets both design expectations and legal obligations. Whether you’re specifying laminated glass for a full-height entrance or combining it with toughened elements for balustrades, we work with project partners to provide technical assurance at every stage.
Safety glass that’s made for your project
The difference between toughened glass vs laminated glass is not just a matter of cost or aesthetics. It’s about understanding how each type performs in different contexts and how it contributes to safety, compliance, and design integrity.
If you’re navigating a complex glazing requirement or need guidance on compliance and specification, speak to our team for advice.