Replies

1. 
   KFC | Mar 17, 2009 08:30am | #1

   Seems sketchy to me, but what do I know? 

   I've only worked the opposite direction- using structure to support brick. 

   Depending on the wythes you use the insert screen tubes so your epoxy doesn't fall in the gap.  And you drill with a wet core bore, not a roto-hammer, so you don't rattle the joints.

   How would you maintain the clearance, or are the beams non combustible?

   Just thinking out loud here...  kinda of a long winded bump, really.  Good luck.

   k

2. 
   IronHelix | Mar 17, 2009 01:13pm | #2

   Gene,

   I can't pull the source for my response, but somewhere from the past the answer to your question popped up as "No"!

   If there is to be a structural member to be supported within a masonry fireplace structure then that member is to be supported independent of the fireplace structure.  This is usualy done with steel or poured columns, which are then encased in the masonry of the fireplace without direct contact to allow for expansion and contraction differential.

   This is my best "FWIW" until I can unearth the source or someone else offers a better reply.

   ...............Iron Helix

    

3. 
   Henley | Mar 17, 2009 02:36pm | #3

   I live in a circa 1972 gullwing. One third of
   the entire roof is sitting on the fireplace.

   Cathedral ceiling with an exposed gluelam carried
   on the inside face of the fireplace.

   I'd be willing to bet codes allow for it still as long
   as fireplace and chimney clearances are met and you have
   stamped plans.

4. 
   Piffin | Mar 17, 2009 02:49pm | #4

   The way the code reads it that it may not be used unless specifically designed and constructed for that purpose. And I think there is a provision in there that requires any wood and fastening to be separated from the flues by a min of 12" of masonry.

   FWIW, I have deconstructed several places in my remos where beams are lt into chimneys and some have suffered, some not over time. in designing one to be a carrier support, one would have to keep a lot of things like thermal movement and stress points in mind. a chimney moves, but a point load element should not, so there is more to it than simply whether the end of a wood beam might be weakened by charring.. Actually I have never seen that, but I have seen stress fractures at the bearing point radiating out.

   The charred timbers I've seen were always run parralel to the sides in unlined chimneys where mortar had worn out or burnt out and in that case, it didn't matter much if it was in contact or an inch or so away.

   I have my own ideas, but not being really qualified, I should not be speculating in public about what specifically would take to deal with that point load

    

    

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5. 
   Piffin | Mar 17, 2009 02:54pm | #5

   The things I mentioned are in the attachment.

   But it does not say how to.

   Short version is get an engineer to design it and you CAN do it.

    

    

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   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
   Excellence is its own reward!

1. 
   Gene_Davis | Mar 17, 2009 03:29pm | #6

   Thanks for that IRC doc, Paul.  Just what the doctor ordered.

   This plan I am working with has a fireplace with a planview footprint of 7'w x 3'd, but a modest firebox size as compared to the overall mass of the block, so can readily accommodate an independent pier within the block, and we'll meet that 12" minimum.

   I have an alternative way to do this, and it may make better sense to do so.  Using a manufactured fireplace such as this Heat'N Glo, we can simply use the chase as structural support.

   We only need to pick up a bearing out at the edge, and the beam will be far away from the doublewall pipe flue.

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