What is best to fire protect old floorboards?

[Gary111]

Hi, I believe that gappy old floorboards should be overlaid for fire and smoke resistance.
The guidance I have read specifies 4mm or thicker high density hardboard fixed at 150mn centres.

I can only buy high density hardboard in 3 or 3.2 mm.

I can get mdf in 4 mm
I can get plywood in 5.5mm


Would you think that ply would be better?

I guess I can double up the hardboard giving around 6mm thickness but it seems very laborious with so many fixings and cutting.

Has anyone got any knowledge of this please?

 

[robinbanks]

Is the ceiling below not boarded?

 

[Gary111]

I think it may be lath and plaster

 

[freddiemercurystwin]

What are you trying to achieve? Is this in a flat or a house or what?

 

[Gary111]

It's a flat, I am trying to achieve 30 minutes fire protection

 

[freddiemercurystwin]

Are Building Control involved? Is this the formation of a flat that was a house before?

 

[Gary111]

No, it's an old conversion, I just noticed the floorboards have gaps and thought it would be better to board over them to reduce any smoke coming through in the event of a fire.

 

[Gary111]

Or maybe use some kind of sealant?

 

[Why Not Indeed]

How much sealant though? Might be less work to use a sheet material than filling hundreds of holes.
Can you afford to lose the height [eg taking bottoms off doors]?

 

[robinbanks]

Or maybe use some kind of sealant?

Has your BCO said you need to do it?

 

[Gary111]

It's mainly boards that look like they have been lifted to fit electrics, so not a huge amount.
No one has said I need it, I just want to improve things.

 

[robinbanks]

I just can't see how it'll be necessary or an improvement - it would generally be the job of a continuous plaster layer in the burning room below that would stop smoke coming into an upper room, plus the underlay and carpet etc but if you're leaving the flooring on show and it looks tatty you could fill it

Can't help but think that any property that is the subject of a set of improvement works in this country would have plenty of other things that could be attended to with greater priority, but if it's getting on for the last thing on the list and is bugging you then go for whatever looks good and is good value

 

[Gary111]

Thanks for your help, yes there's a long list I will be working through for years probably.

 

[Why Not Indeed]

it would generally be the job of a continuous plaster layer in the burning room below that would stop smoke coming into an upper room

From the OPs point of view, that's someone else's responsibility. I can understand why he would want to wear braces when it's someone else's job to put on the belt!

 

[foxhole]

Thanks for your help, yes there's a long list I will be working through for years probably.

Maybe concentrate on work that’s actually necessary .