Safety of PIR IWI beside 5kw multi-fuel stove

[Gaf]

Getting conflicting advice on this. We will have a free standing corner stove (as in it will be sitting in the room) just like the attached image - we just won't have that window. There won't be any wall cladding added around the stove, at least that's our preference.

 

Outside to inside our wall build-up is:

• Block,
• Cavity Bead,
• Block,
• 25mm IWI PIR, (yes not the way many would go)
• 12.5mm Plasterboard with skim finish.

 

On one side we're told we need to replace the PIR IWI around the red wall area on the attached image with something like an "isoboard" for fire safety, on the other side we're told the PIR IWI (unilin, mannok, or kingspan) is perfectly safe in this position.

 

I've tried searching here and wasn't just finding a clear answer. Is it safe enough to go with the 'standard' PIR IWI for a 5kw multi-fuel stove here? I posted here rather than the stoves forum as I thought this query focused more on the insulation than the stove.

 

 

[MikeGrahamT21]

16 minutes ago, Gaf said:

Getting conflicting advice on this. We will have a free standing corner stove (as in it will be sitting in the room) just like the attached image - we just won't have that window. There won't be any wall cladding added around the stove, at least that's our preference.

 

Outside to inside our wall build-up is:

• Block,
• Cavity Bead,
• Block,
• 25mm IWI PIR, (yes not the way many would go)
• 12.5mm Plasterboard with skim finish.

 

On one side we're told we need to replace the PIR IWI around the red wall area on the attached image with something like an "isoboard" for fire safety, on the other side we're told the PIR IWI (unilin, mannok, or kingspan) is perfectly safe in this position.

 

I've tried searching here and wasn't just finding a clear answer. Is it safe enough to go with the 'standard' PIR IWI for a 5kw multi-fuel stove here? I posted here rather than the stoves forum as I thought this query focused more on the insulation than the stove.

 

 

Is there a reason why you can’t switch to a non combustible insulation material all round that area? Maybe your planning on using insulated plasterboard?

If your set on PIR, maybe think about some kind of metal plate behind the stove to deflect some of the heat, and leave a gap behind it for airflow

 

[JohnMo]

We weren't allowed timber battens and had to replace with metal U channel, in that area also. I would add 50mm steel battens (U channel) and then use 50mm Rockwool Flexi or similar, attach the plasterboard to U channel, do the same across the whole two walls - you can see them on the left hand wall.

[Gaf]

Cheers lads.

 

@MikeGrahamT21 Insulated plasterboard was specified by the architect but we're at a stage this can be changed.

 

@JohnMo The stove crew did say to make sure there's no timber battens anywhere near the area. The planned plasterboard is 37.5mm (12.5 PB and 25 PIR. The 50 metal battens with plasterboard would bring us to 62.5, only 3cm more so might be worth it.

 

 

[JohnMo]

Remember PIR is more flammable than wood. If they don't want wood not due PIR will be any good either.