Glass Blocks & Building Regs

[Builder Geoff]

We are developing a small block of flats. The communal stairway and one of the external walls of one of the apartments has a section of glass blocks to be installed.

Having not worked with glass blocks before this is all new to me. All glass blocks appear to have 60 minutes fire integrity and either 15, 30 or 60 minutes thermal resistance. We have asked the BCO what we need to install and he said "60 minutes fire rated".

We can't get a better answer from him (is fire integrity the same as fire rated?) so I'd hoped Part B would make it all clear (apparently not). The wall in the communal stairway is the external wall. I understand the need to protect the walls between the apartments and the stairs, because fires usually start in one of the properties, but the external wall?

Our problem is that glass blocks range from about £3 to almost £20 each, depending on the thermal resistance and that could cost us a small fortune.

Anyone know the rules of glass blocks and fire ratings?

Thanks,

Geoff

 

[tony1851]

Generally, the external walls of a staircase enclosure are not regarded as unprotected areas and do not need to have the same period of fire resistance as the other external walls. This is because the fire risk from a staircase to other nearby buildings is obviously very low.
Part B of the fire regs causes most people problems as they are often 'open to interpretation', as they say, but it's really down to risk.
If you ask an inspector a question and he is not sure himself of the answer - by default he will often give the most onerous response. Perhaps ask him to direct you to the part of the regs where it states that the wall needs 60 mins fire resistance?

 

[^woody^]

You also need to be mindful of the RR Fire Safety Order 2005, which could be more onerous than building regulations.

It's not just the blocks, but the joints and installation generally, and you should need it certifying as a whole and not just a case of buying a certain block.

Whether it's 30 or 60 minutes will depend on the rest of the walls on the escape route, the design and maybe the distances to exits. Really this should be something that the designer gives some thought to, as you don't want it all needing to be changed once the first Fire Safety Risk Assessment is done