Non-combustile Mantle and Top Wall Clearance

[dropshot12]

I am wanting to install the Century CW2900 insert in my existing fireplace. It looks like as long as I add a non-combustible floor covering I will meet all clearances to combustibles except (I believe) the overhead clearance of 27" to combustible top surround and mantle shelf.

I have a 29" high opening with 3 rows of brick above, then mantle and then plaster wall above. This gives me ~40" total of non-combustible height before the plaster wall. The height of the Cw2900 is 22 5/8" and with the 27" of clearance I would think I need 49 5/8" of total height from the hearth floor. So I would be (49 5/8" - 40") = 9 5/8" short.

My plan would be to add either a 12"d slate noncombustible mantle or a 12" wood mantle with a 24g metal heat shield. Would this reduce the clearance needed to within my range?

The NFPA 211 states in section 13.6.2.3 that I can reduce clearances by 66% to a minimum of 12" for combustible walls, does that apply here? Or would it be that I can reduce by 50% to an 18" min for combustible ceilings (with the mantle being the ceiling)? Would either of these work for my situation to reduce the clearance required between the insert top and the plaster wall?

CW2900

- Large size firebox,- Spring faceplate adjustment system which easily adapts to any type of hearth,- Reinforced appliance top with a stainless steel heat shield ,- Cast iron door and ceramic glass,- EPA certified at 2.3 g/h ,- Non-catalytic combustion system,- Designed and made in Canada ,-...

www.century-heating.com

Thank you for your help!

 

[dropshot12]

Any insights would be appreciated! Let me know if you need any more info on my setup.

 

[begreen]

Have you looked into non-combustible mantles? They look great.

Non-combustible mantels

Starting a thread for folks that are looking for non-combustible mantels. These are very realistic, but made from concrete: http://magrahearth.com/natural-wood-series-gallery MagraHearth website http://magrahearth.com/

www.hearth.com

 

[dropshot12]

Have you looked into non-combustible mantles? They look great.

Non-combustible mantels

Starting a thread for folks that are looking for non-combustible mantels. These are very realistic, but made from concrete: http://magrahearth.com/natural-wood-series-gallery MagraHearth website http://magrahearth.com/

www.hearth.com

Yes! I have seen those recommended here, I've been searching this topic a lot. Those do look nice and would be a great option.

I guess I'm wondering if putting that in place of my current mantle would shield the plaster wall above enough so that my clearance to that would end at the height of the mantle. Does that make sense?

 

[begreen]

I think so due to it being flush with the fireplace face and not a "side surround" projection as shown in the clearances diagram. The concerning clearance is for mantel trim.

 

[dropshot12]

Well that makes total sense, thank you for the insight!

I guess my next question would be, would a piece of real slate/granite be sufficient as a non-combustible mantle, or does it specifically have to be bought as a "non-combustible mantle" from one of the shops you linked to?

 

[begreen]

As long as it's non-combustible it's ok. The challenge may be supporting it. If it's combustible then it needs to be higher to meet the clearance requirements.

 

[dropshot12]

Ok, so obviously any piece of actual stone is non-combustible. I hope I dont have too much trouble supporting it. The brick facing sticks out about 3 inches, so the mantle would be on top of that fully in the back which would hold a good bit of the weight. Then I have 2 triangular steel brackets to mount underneath on either end.

Hoping that is enough if I use the right hardware to fasten the brackets into the brick. Just need to figure that out.