What Glasses Are Allowed On Balconies?

There is much confusion and many rumors running around regarding the correct type of glass allowed on balconies and balustrades.

This stems from two reasons; the first being lack of understanding of the required standards and the second a vested interest in sending customers towards a specific product.

I have had customers calling regards a juliet balcony saying they have been told they need to use 15mm toughened glass, or someone who wanted to glaze a landing staircase was told he had to use 19mm toughened glass. Both of the above turned out to be unnecessary and they had their railing made with 10mm toughened.

When glass is used in balconies, balustrades, Juliet balconies etc. there is an obligation to use what is designated as safety glass, this can be either toughened, laminated or toughened &laminated.

Definition of toughened glass: Glass that has undergone treatment also called “tempering” where the glass is heated to close to seven hundred (700) degrees Celsius and using air cooled quickly creating a strong layer on both faces of the glass while locking inside the glass a lot of tension. This causes the glass to become more resistant to impact four times more than regular float glass. When toughened glass breaks it will shatter into thousands of small glass pieces and therefore, not dangerous little bits.

Definition of laminated glass: Safety glass that is made from two or more glass panels with a plastic or resin based interlayer that is allowed to break under impact but must not allow the impacting body to penetrate the panel.

Throughout Europe, excluding the UK, single pane toughened glass is not allowed. Only laminated glass is allowed. But in the United Kingdom the majority of glass used in balustrades is toughened. Laminated glass is slowly becoming more widely used. Due to the extra cost of laminated glass I believe that until legislation turns this into a requirement toughened glass will remain number one in balconies and balustrades.

Thickness and type of glass depends on:

1) The area it must protect
2) Impact class required
3) Size of each single pane used.
4) The distance or depth of the balcony or terrace and..
5) The type of railing, balustrade or balcony

There are three British standards that are relevant to glass classification and specification on Balconies, railings and balustrades: BS6180, BS6399:1 and BS6206.

Please feel free to ask any specific question.

5 thoughts on “What Glasses Are Allowed On Balconies?”


    My query relates to the use of toughened glass for a 19 storey high rise building with pedestrian areas below. Would you regard toughened glass as being ‘fit for purpose’ to balustrades to terraces to each floor that can be furnished with patio furniture and the glass then subject to impact in high winds. Also isn’t toughened glass prone to NiS inclusions that can cause spontaneous failure. Failure and any glass panel in a balustrade system could result in glass falling to a pedestrianised are below and pedestrians would be at risk if glass of any size hit them.
    In terms of ‘risk’ would it not be better to specify laminated?

    1. Several points to consider here, listed below, which should bring you closer to an answer.

      • In terms of the definitions in BS6180:2011, toughened glass in the correct thickness for containment is enough.
      • To reduce the chances of spontaneous failure the glasses can be heat-soak tested.
      • Yes laminated glass can be used, in both our Hybrid and Structural glass systems. But as amazing and stupid as it will sound, there has been a recent change to building regulations de facto BANNING use of laminated glass on balustrades on high rise building (due to fire regulations). We believe this is relevant to approvals after 2018, not sure exact relevant date. You should check with your planning advisor if this applies to your site or not.
      • An external protective film can be added to toughened glasses, we have seen some customers do this in high rise buildings.
  2. The thickness of the glass depends on several factors

    What is holding the glass?
    How that is to be fixed to the structure?

    Is there a handrail or not?

    Glass needs to be able to take the force of applied pressure and wind loads and also act as containment for impact

    Commonly on frameless systems 21.5mm laminated and toughened is used but this must be verified for your use

    Sorry there is no simple answer

    Kind Regards

  3. Jon Larcombe

    I’m carrying out major renovations of my house, and at the same time building in a balcony, which is based on a big and galvanised heavy steel frame as we’re on a cliff top site – next stop West is the USA!

    Height of the balcony floor is 5.5 metres, projecting 1.5m from the wall and 4.0 metres in length. Planning Permission was granted for it, with stainless steel posts and white laminated glass, to minimise impact against the white walls common on Cornish coastal properties.

    I’m finding it extremely difficult to find the Specs. that the balcony needs to be built to. I have specified 1150mm height for the balcony safety rails. Can anyone advise me of what thickness white laminated glass I should be sourcing :- I’m thinking 2 panels 1450 x 1150 mm for the sides and 3 panels approx. 1390 x 1150 for the front panel, and I was looking for 10 or 12 mm thickness of glass – am I anywhere in the right ball park.

    Thanks for any advice you can give, or pointers to the appropriate building regs..

  4. our customer wants an all glass – no handrail – juliet balcony which I know has to be 1100 high from internal FFL but it is 1300wide so what tough glass would you recommend as there does not appear to be any building regs relative to size / thickness etc?


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