Fire stopping at base of plasterboard wall

[Bristol1]

Hi all,

 

We are building a timber frame home and we are currently at the skimming stage. 

 

Building regulations require that every load bearing wall is fire resistant for 30 minutes, hence we have used 15mm plasterboard. We also have a protected fire corridor (stairs and landing) which must be 30 minutes fire resistant. 

 

Our plasterer has fitted the plasterboard approximately 15mm to 30mm off the floor in most areas. I understand that this is fairly standard and the purpose of this is to ensure the plasterboard can’t wick up any moisture from the floor. 

 

However, a 30mm gap at the bottom seems excessive for a wall that should provide 30 minutes fire resistance (albeit the gap will be behind MDF skirting board). I can’t find any guidance or building regulation that states a maximum permissible gap, only vague references online to the entirety of the wall needing to be fire resistant.

 

Does anybody know of the gap must be filled or if there is a maximum allowed gap please? 

 

Our builder has suggested fire foam, but I understand its effectiveness is questionable. I believe intumescent sealant may be a sensible option. However, it would be quite a lot of work (and Sealant!) and I certainly don’t want to do it if it’s completely acceptable to simply do nothing and leave a gap. 

 

If anybody has any experience of this, or is aware of any clear guidance, I would really appreciate your advice!

[nod]

He probably didn’t realise that these walls should have been protected 

He should have slipped a piece of dpc under and sat the board directly on to it 

If you want to do it properly Snap a chalk line at 50 mil and cut back with a multi tool Fill with a 50 mil strip of pb 

[BadgerBodger]

I think this is the detail you are looking for… 

[Nickfromwales]

Quickest and easiest thing for you to do is to mix up some drywall adhesive and fill it in, with a bit of DPC laid down first, as @nod states. Leave that DPC long, do the filling, and then cut the excess off when you've skimmed it all.

 

12.5mm PB with skim is 30 min, no need for 15mm PB as that gives 30 min when no skim is applied.