clearance Question

[fishinAK]

So heres the deal. I have a hearth pad that is 40 inches deep and 50 inches wide. With a vented/spaced 4.5 inch brick back wall.
I want to buy a stove that requires a hearthpad dimension of 43 inches deeep and 40 inches wide. With a required 10 inches between the back of the stove and a combustable wall.
Since my back wall is the vented brick can I just scoot the stove back closer to the wall to make up for the few inches that I am missing in the front of the stove? How close can I get to the back 4.5 inch vented brick back wall.
First what is code, and second what would be safe 99.99999% of the time?
thanks for all you help guys

 

[KP Matt]

What does the 4.5" refer to, the thickness of the brick wall?

A properly constructed brick shield should be able to reduce clearances by 50%, at least here in Canada.

However it seems to me that they can't be reduced closer than 12" or so, regardless of what kind of heat shield.

 

[MountainStoveGuy]

If you have a solid masonry wall, then there arent any clearances to non combustables, you only have clearance to cumbustables. There are three types of situations, combustable, non combustable, and protected. Protected would be a non combustable, with a 1" air space, on top of a combustable. You get a 1/3 reduction in clearance by NFPA 211. If its combustable you have to follow the stove specs, and if its not combustable you can get as close as you like. Not all stoves reconize NFPA211, so check the manual online before you purchase a stove. As far as being safe 99.9% of the time, i would recomend you step up that last 1/10th of a percent and install it per the manufacture directions.

 

[Shane]

I thought it was 2/3 for a protected wall with an airspace and 1/3 a protected wall without an airspace?

 

[MountainStoveGuy]

Shane, i havent looked in a while, i have always used 1/3 with a airspace. I will have to look it up to be shure.

 

[KP Matt]

There's also the question of the dimensions of the brick shield, doesn't it have to be 36" wider than the stove and extend up some specific distance above the stove?

 

[MountainStoveGuy]

from what i have found, a wall with no airspace doenst count for anything, and all the manuals i have looked up online the protected wall with a 1" airspace is ~1/3 reduction. I have never heard of the 2/3 rule, doenst mean that it doesnt exist, i just cant find any data to support it. As far as how big the shield needs to be, it needs to be as large as the clearance for the stove states. I have never seen a rule that says is needs to be x wider and y taller then the appliance, once again, im not saying there isnt one, just cant find any data that supports it.

 

[Shane]

NFPA211-39 has a table listing clearance reduction methods. This is based on 36" clearances so a masonry wall with a min. thickness of 3 1/2" without a ventilated air space allows for a clearance reduction of 33% so 24" clearance. Then there are several methods listed that incorporate various materials with an airspace that allow for a 66% reduction. As for this particular situation though and more than likely a manufacturer will not list a clearance reduction method that does not incorporate an air space.