Replies

1. 
   rjw | Jan 30, 2006 01:20am | #1

   The manufacturer's instructions will specify clearances, especially above: 20" deep mantle? None of the installation instructions I've collected show a mantle projecting more than 10" from the front of the firebox

   General rule of thumb: nothing combustible should project past a 45 degree angle from the top and sides (for 48"): a 6" deep mantle leg needs to be at least 6" away from the outside of the casing, and a 6" deep mantle needs to be at least 6" up from the top of the casing (but manufacturers' specs will differ.)

   FWIW, I inspected a house a couple of weeks ago with a direct vent gas log fire place with the mantle well within the manufacturer's specs, but with the gas log set burning but the fan not running, the bottom of the mantle reached 175 degrees! Much too hot for safety over time because of pyrolysis.

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1. 
   Stilletto | Jan 30, 2006 01:52am | #2

   the mantle will project approx. 12" from the front face of the finished fireplace the box I built today is 8" deep so thats where I got the 20" mantle figure. The posts in question will be directly in front of the fireplace so I think shes out of luck.  The box I built only extends 6" to each side of the fireplace and returns to the wall couldn't make bigger sides on the box due to windows on both sides.

2. 
   Mark_T | Jan 30, 2006 03:09am | #3

   I just went through a somewhat similar situation where the HO did not want a hearth, which seemed like a bad idea.   I checked code, company who installed fireplace, etc.  nada.  What I found out is that with these metal pre-fab fireplaces it is entirely dependent on what the manufacturer says is OK.  Get the model number off the unit and contact the manufacturer for clearance requirements.  In my case I was able to find the proper information (install instructions) on the web.

3. 
   Piffin | Jan 30, 2006 04:05am | #4

   Those kind of projections will never meet code. She is trying to burn her house down.

    

    

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1. 
   Stilletto | Jan 30, 2006 04:24am | #5

   Thats what I had mentioned to the lady I explained to her that the fireplace in the picture she had brought to the job today was built entirely of marble posts, hearth, mantle and all I told her we had an agreement for a fireplace constructed with steel studs covered with durarock and faced with cultured stone if she no longer wants that and wants to pursue the route I have explained to you, that I will walk away and wish her the best of luck because I don't want any part of it.  

4. 
   andy_engel | Jan 30, 2006 05:23am | #6

   The IRC says to follow the manufacturer's instructions on zero clearance units. For masonry units, and I'd suspect as a general default, the IRC allows no combustibles within 6 in. of the firebox opening. Between 6 in. and 12 in. from the opening, you're allowed 1/8 in. of projection for each inch from the firebox. So at 6 in., the projection can be 3/4 in. At 12 in., it can be 1 1/2 in. Beyond 12 in., the IRC is silent.

   Andy

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5. 
   wrudiger | Jan 30, 2006 05:54am | #7

   The specs vary quite a bit depending on the manufacturer.  Here are the clearances for my QuadraVent.  Given how hot the granite facing gets 12" above the fireplace I'd consider them absolute minimums: