SFPE Discussions

Coated Concrete Floors+ Timber Decks

Q1: Coated concrete floors and C/ AS2 internal spread of fire:
I read cl 4.7.13 and have referred to it in the past [as well as Table 4.5] for vinyl and carpet [flexible tile or continuous floor coverings] But what about bare / polished concrete floors which then have a clear or coloured paint/ coating put on them?
Is critical radiant flux applicable here? It doesn’t seem so to me.
I would expect something about floor finishes in the Surface finishes Table 4.3 for Floors. But it only mentions walls and ceilings and is silent on floors.
It seems to me these is a gap here in the Acceptable Solution here.
Can anyone help?

Q2: New timber deck between upper and lower firecells:
If two firecells are one above the other [say in a 2-storey concrete/ concrete block building] , and they both have openings in the same external wall which line up vertically with one another, then C/AS2 cl 5.7.12 and Table 5. 4 give us spandrel/ apron options to prevent fire spread between the two firecells. A 600mm wide apron means no spandrel is necessary.
Now I have had a query from someone who is in the upper firecell and wants to put a 3 m wide [say] timber deck between the two wall openings [assume both are ranchsliders]
Do I only have to fire-rate a 600mm wide fire-rated deck underside strip adjacent to the wall to protect the upper firecell from the lower one?
Or should the whole deck underside be fire-rated?
And what about the deck support posts? I assume they would have to be fire-rated too?
Thijs Drupsteen CPEng Friend Member, SFPE
oated Concrette Floors; Timber Decks

Hi Thjis
Q1. C/AS2 4.17.3 and Table 4.5 is just a regurgitation of NZ Building Code C3.4(b) which is the law. If you don’t think this legal requirement can be met then you have the option of going for a waiver. I think the cheaper and most expedient option would be to get your floor tested or use another tested product.

Q2. This topic is well canvased in another post at Fire rating requirements of external balconies - General - SFPE Discussions.

Regards
Robert Peart