Protecting MDF cladding to resist the spread of flames

[dave_104]

Hi

I'm planning to install MDF cladding internally on a new vaulted ceiling. Buildings regs have just come back to me and said the following -

The ceiling of your residential extension should be protected to resist the spread of flame over its surface according to classification C-s3, d2

Could anyone translate that to English for me please?
What could be done to ensure I meet that requirement? I think these are standard MDF boards and not anything special. I've seen a few fire retardant paints for sale although the boards will already be primed. I'm not sure also maybe if the boards could be treated with something either?

It's a roof on a single story room, no room above. Roof has PIR between the rafters and across them on the inside too.

Thanks
Dave

 

[Scally-Ho]

Perhaps they mean that the ceiling should be clad in something along the lines of Enviroboard?
I use Enviroboard when I'm preparing a newly acquired property for rental. It's a product that my area BCO definitely approves of and ticks all of his/her boxes.

Enviroboards Fire Board

Fire Board and Fire Boarding Alternative Supalux Masterboard. Fire Barrier Products

www.fireboards.co.uk

 

[freddiemercurystwin]

What your BCO is saying is the MDF must achieve a fire classification of C-s3, d2, so to be 'that guy' for a moment that means:

The C figure is how combustible the material is (C is medium)
The s figure is how much smoke it produces, s1 (little) - s3 (a lot)
The d figure is how many flaming droplets the material drops, d0 (none) - d2 (a lot)

But really you don't need to worry about any of that, what you need is a fire treatment you can apply to your MDF to achieve that fire classification or better.

So now it's over to you as the next bit is the donkey work, get in touch with someone like Rawlins Paints https://www.rawlinspaints.com/timber-plasterboard (phone don't pi$$ about emailing them) and they will be able to select a suitable primer/paint combination, they will ask you what you want to paint, how thick it is etc and what classification it needs to achieve and from there they will be able to select the right combination of primer/paint, there are so many combinations and different products it's not straightforward without spending ages reading up on each of their products, I've dealt with them before they know their onions, the other great thing about Rawlins Paints is they have all of the data sheets etc available online that you can download/link to if your BCO asks for them, which they may well do. It may get a bit more complicated if your boards are already primed but give them a ring and see what they say.

 

[^woody^]

Plasterboard, get it signed off then fit your cladding - when building regs do not apply.

FYI, for you and the inspector interior decoration does not come under building regs, and emulsion paint and wall paper is not resistant to fire spread and no wall cladding in a domestic setting comes under building regs.

 

[Tigercubrider]

Trade Fire Retardant Timber Plywood MDF Medite & FR Boarding : Creffields

Creffields are specialists in the supply of FR plywood, MDF, wood & laminates. Supplying exhibition, conference, television, film, theatre & scenery trades

www.creffields.co.uk

 

[dave_104]

Thanks for all your replies. In the meantime I found this which gives the charts - https://hspfireprotection.co.uk/information-and-advice/4_fire-ratings-explained.html
To me, if it's C-s3, d2 then that seems to translate to it being acceptable to produce a high volume of smoke, acceptable to have high/intense dripping droplets, and only the reaction to fire needs to be improved from D (what the MDF supplier just told me) to C. Probably just a coat of fireproof/resistant paint will solve that - I'll ask Rawlins as Freddie's suggested. Also thanks Woody, that makes sense too - just like when people use lining paper over ceilings if there's cracks (I know there's fire retardant lining available but suspect many people use cheaper paper).

I'd done another room in an identical way, and B-Regs didn't say a thing!