Fire-rated glass doors - what are the choices?

A few years ago, it used to be the case that if you wanted a fire-resistant glass door, your options were very limited.

For a long time, wired glass was pretty much the only product on the market that could pass fire-rating tests. But the limitations of its relatively weak impact resistance meant it could only be used in either small panes or in areas where there is a low risk of breakage.

However, advances in glass manufacturing processes mean there has never been more choice when it comes to the fire glass market.

Of course, wired fire glass is still used in certain applications, but now we also have the options of using safety wired fire glass, specially tempered fire glass, ceramic fire glass and intumescent laminated fire glass.

Wired fire glass doors

Wired glass is still a common sight in institutions like schools, offices and factories. It is a cost-effective product and can be a useful product for certain applications.

However, wired fire glass does have a number of limitations. It offers integrity-only fire protection, meaning that while it will stop the spread of flames and smoke, it doesn’t insulate against heat radiation.

It also has the drawback that the wire within the glass actually weakens it, making it more prone to accidental breakage. The thin wire used in wired glass can also be relatively weak, and the potential injuries caused by the combination of broken glass and broken wire don’t bear thinking about.

For these reasons, wired fire glass cannot be used in locations where safety glass is required. When it comes to doors, this applies to any pane of glass bigger than 250mm wide with an area of 0.5m² that sits partly or fully below a threshold of 1500mm.

So when it comes to fire-rated glass doors, wired glass can be used for vision panels, but not much else.

Safety wired fire glass doors

Safety wire fire glass has been developed to allow wire glass to be used in areas where safety glass is required.

The wire glass has a special film added to it which holds the glass in place should it break.

However, many people feel wired glass has a certain ‘institutional’ appearance, and despite its affordability, many architects and interior designers now shy away from specifying it, preferring instead to opt for the more modern clear fire glass options in doors.

Clear fire glass door options

The three remaining options, tempered fire glass, ceramic fire glass and intumescent laminated fire glass all offer clear-glass solutions for fire-rated doors.

These three products all meet safety glass requirements so are safe to be used at any height in fire-resistant glass doors.

There are a number of factors to consider when choosing between the three.

Tempered fire glass is a reasonably cost-effective option, which can make it appealing at first sight. However, tempered fire glass is not able to pass the hose stream test.

Tempered glass is highly resistant to heat, but when subjected to cold water, the sudden change in temperature can cause the glass to shatter.

This means tempered fire glass carries a maximum integrity rating of 20 minutes, with no insulation rating, so is somewhat limited in its applications.

Ceramic fire glass is a very versatile and useful product. It can handle 425°C changes in temperature, can be tinted, clear or mirrored and can have a fire rating up to 180 minutes.

Because of its excellent heat resistance and durability, ceramic glass is used for applications such as glass hobs and fireplaces and is also suitable for use in fire-rated glass doors. However, it doesn’t offer any level of thermal insulation and also comes with a premium price which can be prohibitive.

For the optimum protection in both integrity and insulation, the product of choice is intumescent laminated fire glass.

This product is a laminated glass with clear intumescent interlayers which, in the event of a fire, react to expand and transform into a rigid, opaque and heat-absorbing fire shield.

Tufwell have recently started stocking Pyrobel, the leading range of intumescent laminated glass, which is available with a range of fire ratings up to 120 minutes for both integrity and insulation.

Pyrobel has bi-directional fire resistance and also offers excellent acoustic insulation. This makes it ideal for applications like fire-rated glass doors and fire-rated glass partitions.