Does adding plaster to drywall count?

[JRP3]

I don't even know what a "higher fire rating " means.

I've seen claims that it lasts longer than type X drywall:

Material Type	Thickness	Fire Resistance Rating
Cement Board (Durock)	1/2 or 5/8 inch	Up to 2 hours (with proper installation)
Standard Drywall	1/2 inch	About 30 minutes
Type X Drywall	1/2 or 5/8 inch	45 minutes to 1 hour

Type X drywall is better at stopping fire than regular drywall. But it still does not work as well as cement board. Builders pick cement board for places that need more fire safety.

Cement Board Fire Resistance Explained for 2025

Cement board fire rating typically ranges from 1 to 2 hours, offering strong fire resistance for walls and ceilings when installed in tested assemblies.

sulfycor.com

 

[stoveliker]

Yes, but this is of zero consequence.
That matters more if you have a wall separating two spaces where fire should not spread from one to the other. I.e. as a fire barrier.
For a stove install as in the pics above this is not really relevant. (Once you have fire outside of the firebox, the excrement already has hit the air-moving device...)

You're overthinking this. Adhere to the clearances (that have been tested, i.e. shown to work), and you'll be good.

 

[all night moe]

You're thinking in the wrong pretext. Clearances are for spontaneous combustion and not to stop or delay the spread of fire.
like stoveliker mentioned about the wood studs behind the cement board. If enough heat is transferred through the cement board, the studs will suffer the same result.

The heat shield with a 1'' spacer is key when clearances are not enough to meet codes.

 

[JRP3]

You're overthinking this.

It's what I do 🤪

 

[stoveliker]

I get it!