# How to make a flammable surface non-flammable?



## WireNut (Jul 30, 2013)

For the purpose of clearance from flammable surfaces, how can I make a flammable surface considered "non-flammable"?  For example, if I need 36" clearance from flammable surfaces and have a wood wall 24" away....that's a no go.  However, if I have a cinder block wall between the wood wall and the wood burner, that is ok.

So, if I use non-flammable (Roxul stone wool) insulation and gypsum board between the wood burner and the flammable material, does that make it a non-flammable material?  I know no one here can give me a "what is legal" answer, but I'm wondering if anyone else has had this experience in the past.  I am going to check with my insurance company, but before I hit up my building inspector I'd like to have my ducks in a row.


----------



## heaterman (Jul 30, 2013)

There are a number of ways you can achieve what the code books call "reduced clearance". They all involve using a non flammable material in between the source of heat and the combustible surface(s).

The method I see used and approved most often is to place a piece of metal between the heat source and the combustible surface, leaving an air gap at the bottom to create a natural "draft" behind the panel. This air flow keeps heat from accumulating on the combustible surface. Sometimes an inspector will ask for 2 layers of metal with air flow between each depending on the temperatures and type of surface involved.

The other method is to basically build a wall, usually masonry or stone of some type and insulate behind that to keep heat flow from going through to the combustible material behind it.


----------



## WireNut (Jul 30, 2013)

heaterman said:


> t





heaterman said:


> There are a number of ways you can achieve what the code books call "reduced clearance". They all involve using a non flammable material in between the source of heat and the combustible surface(s).
> 
> The method I see used and approved most often is to place a piece of metal between the heat source and the combustible surface, leaving an air gap at the bottom to create a natural "draft" behind the panel. This air flow keeps heat from accumulating on the combustible surface. Sometimes an inspector will ask for 2 layers of metal with air flow between each depending on the temperatures and type of surface involved.
> 
> The other method is to basically build a wall, usually masonry or stone of some type and insulate behind that to keep heat flow from going through to the combustible material behind it.


 

The second method that you're describing is what I'm looking at.  Putting up a 4" piece of Stone Wool insulation (2150° F melting point) to prevent heat transference and cover that with a piece of sheet metal or hardie board for fire resistance.  If I go 18" beyond the outer edge of the boiler on all sides, and seal any spaces between individual pieces with a 3M™ Fire Block Sealant FB 136 or equivalent, it seems to me that would exceed the fire protection I would get over an extra 11" of air (I'm 11" shy of the manufacturer's recommendations).  I'll check with my insurance company and see what they think.  If they give me the ok, I'm back to the plan of putting the boiler in the basement (our area put in really strict regulations on installing outdoor wood boilers...and I don't want to argue semantics of putting an indoor boiler in an outdoor shed.)


----------



## ewdudley (Jul 30, 2013)

Requirements specific to NY:

https://bulk.resource.org/codes.gov/ny_mechanical.pdf

Check out Section 803 p.66 and Section 308 p.23.


----------



## WireNut (Jul 30, 2013)

ewdudley said:


> Requirements specific to NY:
> 
> https://bulk.resource.org/codes.gov/ny_mechanical.pdf
> 
> Check out Section 803 p.66 and Section 308 p.23.


 
Wow!  Thanks!  Page 23 gives me exactly what I was looking for.  

This forum has to be the best resource for someone like me who loves to tinker but wants to make sure they do it right, there are tons of people on here willing to help where my google-fu fails!


----------



## WireNut (Jul 31, 2013)

I just got the ok from my insurance company!  The basement it is.  So the building code just made me move a fire risk inside of the house instead of putting it outside.....just so I can call it an "Indoor" wood boiler.  Strange effects when people pass laws about things they don't understand.  Same emissions will be coming out of the same height chimney...... lol


----------

