Fireproof hidden beam?

[WMP]

Hi,

We have a loadbearing hidden beam (I.e in the ceiling joist void). Question is for structural beams in a void do you need to take fireproofing measures? I have seen one comment on here saying that if the beam is in a ceiling and not boxed in then no further measures are needed but just use normal PB for the ceiling as normal. Wanted to double check before I approach the building control inspector as this would be my preferred option.

Thanks in advance

 

[DevilDamo]

My opinion would be a steel beam hidden between joists is no different to your normal joists. As you wouldn’t fire protect the joists, you wouldn’t need to fire protect the beam. The requirement is normally to those beams that sit below ceilings. If you already have a few beams on the project, there isn’t any harm I having them painted prior to installation.

I’d be interested to hear other’s views though.

 

[DevilDamo]

Btw, is this a 2-storey or 3-storey property?

 

[alictait]

I had it specified on my plans that the beams had to be fireproofed (despite the wooden ones not being), seemed absolutely bizarre. Anyway I bought fireproofing paint for one beam and double wrapped the other in plasterboard. I took lots of pictures which the planning department were not interested in the slightest about.

The fireproof paint is only acceptable though if bought through an official seller and calculations have been provided based on the load the beam will be bearing. Like I said though - my local planning department clearly didn’t care, despite it being specified(I am in Scotland).

Mine is a 3 storey.

 

[^woody^]

The requirement is for fire resistance to floors, ceilings and walls and any exposed beams in high risk areas. If a beam is not exposed and not in a high risk area, it does not need additional protection as it gets that from the floor/ ceiling/ wall around it.

 

[alictait]

The requirement is for fire resistance to floors, ceilings and walls and any exposed beams in high risk areas. If a beam is not exposed and not in a high risk area, it does not need additional protection as it gets that from the floor/ ceiling/ wall around it.

Mine weren’t exposed, I kinda got the feeling though that my architect threw it into the spec just incase.

 

[^woody^]

Yeah perhaps the architect was crap.

 

[alictait]

Yeah perhaps the architect was crap.

Former planner, however I think he was mainly used to industrial settings.

 

[WMP]

Thanks for the replies. It's a 2 storey and no specs from were detailed on the plans. As the 2 load bearing beams are already installed so painting would be difficult at this stage. I'm sure that the beams would be considered a high risk area though. I guess I'll have to check with the inspector but at least I can give small challenge.

 

[tony1851]

The Building Regs specifically excludes any structural element supporting only a roof from requirements for fire protection.

 

[Leofric]

Are you talking about a beam within the first floor or in the roof space ? If in first floor half hour fire resistance required and would be provided by 12.5mm plasterboard and skim ceiling. If in roof space as Tony 1851 states , but plasterboard ceiling would provide fire resistance anyway.

 

[WMP]

First floor. Spoke to the building inspector today and the whole ceiling downstairs will need to be done with fire lined PB. He was interested in the span first but at 5m he said it definitely would need it.

Thanks

 

[Tally101]

We had the same issue when we knocked a wall down between kitchen and dining room. Building inspector wanted it either double boarded with fireproof pb or fireproof paint which we had done and was certified

 

[DevilDamo]

half hour fire resistance required and would be provided by 12.5mm plasterboard and skim ceiling.

Just one layer of 12.5mm plasterboard along with a skim finish achieves 30mins? I’ve always spec’d 2 layers of 12.5mm or 1 layer of 15mm Fireline (or equal and approved) to achieve min. 30mins.

@WMP... Is your BCO saying first floors in a 2-storey house need to provide min. 30mins from the underside in order to protect the timber joists?

 

[^woody^]

Just one layer of 12.5mm plasterboard along with a skim finish achieves 30mins? I’ve always spec’d 2 layers of 12.5mm or 1 layer of 15mm Fireline (or equal and approved) to achieve min. 30mins.

12.5mm plasterboard and skim will be 30 minutes. Think about it, ceilings need to be 30 minutes, do you double-board all your ceilings?

The issue with achieving 30 minutes is the joints. So they need to be dealt with using large enough [secured] timber sections, or double boards ..... to cross the joint, not for the actual thickness of two boards.