Fireplace base

[JimMorrissey]

I'm rebuilding a fireplace and noticed the firebox base is cracked and I did some more damage removing the old tile hearth. I'm talking about the actual base of the firebox where the andirons sit and the fire is built.

Question: What type of concrete can I use to pour over the existing material to repair it and make it look better? Would the premade concrete landscaping slabs work....cut them to fit and grout inbetween? Does it matter what is used? I guessing yes, that's why I'm asking /forums/images/graemlins/smile.gif

The base area is 2' wide X 1.5' deep.

 

[jinman]

Jim, my fireplace is lined with solid firebrick. They are a kind of yellow-khaki color and very precise dimensions so they fit together almost perfectly before being grouted. I believe the brick supplier can supply you with some special fireplace grout that will have a minimum expansion factor. Honestly, the bricks are about 3" thick and much larger than normal brick. They will not expand and crack like normal brick or pavestone. If you don't have a metal insert, then I think what you really want is firebrick in your fireplace.

 

[JimMorrissey]

Yeah, that makes sense.....I just don't want to have to take the whole base out to make room for the 3" firebrick. Maybe that's what I'll have to do. I'm hoping somebody will chime in with another stragegy that a lot easier /forums/images/graemlins/wink.gif

 

[CurlyDave]

I just don't want to have to take the whole base out to make room for the 3" firebrick.

You may be able to just replace the damaged bricks & leave the rest alone.

Try to get one out and take it to the brick supplier.

I don't know of anything which will substitute for firebrick.

 

[Highbeam]

The folks that build little forges use firebrick and/or just the fireproof grout. Imagine making a grout bed for a shower or something. Just use a solid bed of the fancy mortar. There's a name for it that escapes me but the fireplace guy ought to know and it comes in bags like regular grout.

The actual spot where the metal grates rest on the base would benefit from some type of hardening so that they don't tear up the bed.

Don't use regular brick or concrete.

 

[JimMorrissey]

That's the problem, there is no brick on the base to replace. It's just concrete or something that looks very similar to concrete. It was clearly "poured" at some point long ago.

 

[Defective]

Jim,

Your fireplace base is probably simple poured concrete. It's not that uncommon. This is likely why it's cracked.

If you want to fix it up without too much work, pour in an inch or two of refrectory cement over the existing floor. Clean the surface carefully. Build a form by placing a 2x2 or some such across the opening & weight it down well. (I'd think about grinding it) You can buy refractory cement in bags just like regular cement. Mix it according to the instructions on the bag and pour it in. Trowel it to a smoth surface and give it lots of cure time. When it's done, start with small fires to break it in.

 

[Buck]

I've seen that fireplace cement at Lowes if you don't have time to talk directly to a professional.

 

[Highbeam]

Ah yes, refractory cement. It may not be as tough as concrete so in certain spots you could mortar in the thin firebricks to set your metal grates.

 

[JimMorrissey]

Thanks. I'll look for the refractory cement locally. Sounds good....