Hello: I am a diy and am relocating a gas fireplace. It backs on an outside wall with one floor joist parallel to the wall under the fireplace. The joist is 2x10 x25ft. Beneath is a wall on an concrete basement floor that crosses at 18ft, 2x4 with no header but shimmed at the top( its a finished basement so it’s hard to see what is what) The base of the fireplace is centred on the 25ft span and is 20 x 77 inches. A lot of the construction is fastened to the wall with 4 inch screws to the 12ft peak. So far it weighs about 700lbs but I have yet to apply a stacked stone floor to ceiling finish. How much further in weight can I go? Should I build a concrete footing beneath in the basement?

  • Our local contractor puts in some kind of concrete foundation if he is putting in a stone fireplace instead of an inset type fireplace. Pretty easy here because there are no basements in the area. – blacksmith37 Nov 25 '19 at 2:47
  • Thx blacksmith37 I’m thinking better be safe than sorry! – Doug Nov 25 '19 at 3:06
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    Just to be sure, is the stacked stone natural stone that will be 4-5" thick or a veneer stone set with thinset to backer board fastened to the studs/framing? – Jack Nov 25 '19 at 5:55
  • The Code allows a maximum axial load on an isolated footing (as opposed to a continuous footing) of 9,000 lbs. before it needs to be “designed”. (See ICC R403.1.2.1) – Lee Sam Nov 25 '19 at 7:45
  • Is it going to be a masonry fireplace with stone veneer? – Lee Sam Nov 25 '19 at 7:47

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