Skimming over intumescent sealant joints?

[Jonesyme]

Hi, I'm doing a loft conversion, and have just put the pink fireline plasterboard across my new 1st floor ceiling. Building control are asking for intumescent mastic in any gaps between boards. There's quite a lot of gaps, typically up to about 7mm wide, both in the plane of the ceiling and at edges with the skeilings (I could have done better...)

I plan to use the intumescent acrylic sealant, then scrim over the filled joints before skimming with multifinish, but I'm a bit worried that this will lead to cracking along the joints. Does anyone have experience of this please?

Thanks, P

 

[dontbelieveawordofit]

intumescent doesn’t shrink, only expands. so shouldn’t crack. 7mm is nothing really and good by anyone’s standards.
If your’e in any doubt use a 4” wide scrim . if you also 2 coat everything your skim will take longer to dry out , the quicker you dry it out the more likely you’ll get cracks now or later.

 

[Jonesyme]

Thanks for your quick reply. I will go for it as you suggest.