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cracked fireplace floor

tylercc's picture

the floor to my fireplace has cracked and chipped. Do i need to replace the entire thing? or can I just use some refractory mortar and fill in the cracks and chipped area?

fireplace (post #207915, reply #1 of 14)

It should be lined with firebrick.  Bottom, sides and back.  High heat and concrete not a good combination.  It would not pass any building code I know of.

cracked fireplace floor (post #207915, reply #2 of 14)

I agree but unfortunatly I am renting the house, the person who owns the house is a house inspector, so I don't know what he was thinking!!!!(There are a lot of questionable things like that in this house) I don't know what was used in the beginning, but if I used some refractory mortar would that solve the problem? So I don't have to pay for his mistakes.

fireplace (post #207915, reply #3 of 14)

I don't know of anything that will help.  It is just not designed as a wood burning fireplace.  Suggest you get a signed statement from the owner that you are not resposible for damage to the fireplace.

You could ... but (post #207915, reply #5 of 14)

You could patch it with motar of some kind.  Then again it is a rental.  But if it bothers you buy a few firebrick adn lay them in there.  You don't need to mortar them in there.  The purpose is just to keep teh heat off the cement.

Problem solved


 I am renting the house WHY (post #207915, reply #6 of 14)

 I am renting the house

WHY are you on the hook to repair it? 

Refractory (post #207915, reply #4 of 14)

The key word is refractory. If you use fire brick you still have to use refractory mortar. Chances are the firebox was precast using refractory concrete. This would meet virtually any code. Refractory concrete is used to cast fireboxes and hotfaces for ovens and fire places. The only problem I can see is that your patch would have to be thick enough so as not to break because I'm not sure how well the patch would adhear to the bottom.

Fireplace (post #207915, reply #7 of 14)

DoRight.  Your idea would be better than trying to patch it as he was thinking.  The problem is that in time the back and side can spall also.


Mike. If the fireplace is made of the material you are talking about,  why is it spalling?  Just a thought.

Metal (post #207915, reply #8 of 14)

Cut a piece of metal to fit the bottom.

fireplace (post #207915, reply #10 of 14)

Thank you all for your solutions they have been very helpful. So lets say that the owner want to fix it(the right way) what should he do? and the reason why I am finding solutions to the problem is because if I don't he will either not fix it or take two years to fix it(not joking). So if I have the solution I might be able to get him to fix it in a couple months. 

If the fireplace is resting (post #207915, reply #11 of 14)

If the fireplace is resting on fireproof materials below (concrete slab, eg) then it's not clear that anything needs to be done.

The most logical "fix", if needed, would be to dry-set half-thick refractory brick, or install a panel of some other refractory material.

The damage may be due in part to building fires directly on the floor vs using a proper fireplace grate.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Could be.... (post #207915, reply #12 of 14)

Could be that beating on the fire with a poker would cause some damage.

To do this right I would line (post #207915, reply #13 of 14)

To do this right I would line it with firebrick.  At least line it with firebrick splits and refractory mortar.  The only other thing that could be done is chip out the concrete down to the mesh and then patch it with a refractory concrete.  If the owner wants a quick fix which I don't recommend, he could use a modified thin-set like flexbond to parge the area.  I'm guessing it will delaminate in the future though.

If you're in a place where (post #207915, reply #14 of 14)

If you're in a place where materials are hard to come by just google pizza oven supplies and you'll get a number of places for refractory mortor, fire brick, and other such things.

since it's a rental I'd probably just pick up a couple of large pizza stones and cut them to fit.  A diamond blade will cut through them no problem.

If I could edit my location it would say I'm now in Reno :-)