Finishing firebrick chimney?

[thickstrings]

Re: Finishing firebrick chimney?

Thats good! back in post #5 I wondered why the crack did'nt go to the bottom....Did'nt know you were burning in it.... I'd do the floor to..and seal it.Then ,on to the oven....

[caspian]

Re: Finishing firebrick chimney?

I think i figured out the reason for the cracks. I think heat and water in the block may be the cause. The fireplace is huge (5 feet wide 3 feet deep). I make big fires throughout the year unless there is a bunch of snow on the ground.
The interior of the fireplace is lines with 1/2 refactory bricks. I am going to put another layer of fulls along the back and sides to add insulation to protect the CMUs.

After looking at the solid base, i can't figure any other reason.

[thickstrings]

Re: Finishing firebrick chimney?

Sounds like a plan!

[caspian]

Re: Finishing firebrick chimney?

Will run the taper of the base (about 1' away) into drain tile to dump it into neighbors yard (evil grin). Should do the trick

[thickstrings]

Re: Finishing firebrick chimney?

Have a beer for me! .... Pray to St. Jude, The patron saint of impossible tasks...lol P.S. If there is no water there, there is nothing to freeze.. most base failures is water related.....the rest is compaction......seems you hit the daily double....

[caspian]

Re: Finishing firebrick chimney?

10-4. Will angle the new pour away from the base then follow up with drainage away.

Really wish you were closer so we could look at this for awhile with a beer. (And a shovel. Lol)

[thickstrings]

Re: Finishing firebrick chimney?

If you back fill high, it will force the water towards the fireplace, down and away is what you want...I think the water is running down the fireplace walls and under your base...get that water out of there....

[caspian]

Re: Finishing firebrick chimney?

Going to dig 8"-10" along the rear where I already dug and add a footer and hope that helps. Also going to leave the cracks open to allow for escape for water. Since I don't know where it came in, trapping it would only hurt me.
Also going to back fill high with dirt to insulate against frost/freezing.

[thickstrings]

Re: Finishing firebrick chimney?

I guess you could caulk, you are in uncharted territory....and yes, the 20" in a single pour would have been more than enough...just try to get some concrete under and flush with the bottom of your base thick enough to act as footings. It may very well fall some more, but, the footers should save it..Hope this helps....

[caspian]

Re: Finishing firebrick chimney?

Water surely got in there since this has been a 2 year project and we deal with Ohio winters. It will face one more winter before I can face it with stone. Should I try to fill/caulk cracks or leave them so there is "drainage".

I will dig down a bit more, them backfill with concrete and form a channel to funnel the water away.

I didn't intend for the base to be layered, just didn't know what to do other than pouring a 20" pad.

I really appreciate your time on this.

[thickstrings]

Re: Finishing firebrick chimney?

There has to be a reason for the cracks.. I would still put in the concrete as discussed, and make a place for the runoff..... Perhaps water got into the layers and froze? Generally, foundations aren't poured in layers.. Mono pour or a wall on a footing. Its holding the whole thing up.....more is good!

[caspian]

Re: Finishing firebrick chimney?

Ok, I dug out 32" of the rear to reveal the foundation. As you can see, it's solid. What really has me perplexed is the crack along the back wall, but when it gets down to the foundation, there is no visible failure (photo 2). Note: I poured the foundation then built up the foundation with 2 layers of CMU to bring it to level with the patio. Those are the 2 sloppy courses you see.
I will dig out the remaining 40" along the back to inspect the foundation. Assuming there is no failure, am I going to be ok? When I fill should I just fill with concrete for good measure?

[thickstrings]

Re: Finishing firebrick chimney?

One more thing, as long as you are in fix mode...Give the water.[rain,snow] a place to run off...like a gutter pan or a scupper. Keep the water away from going straight down, and eroding the base. With all the hard surface, there is no absorbsion,so it will run, and cut...Good luck! ....and lets see some pic's of the repair.

[caspian]

Re: Finishing firebrick chimney?

Is it possible to pull all the rock back? Then, undercut,dig, to the bottom of your slab, to expose the underneath of the floor....get a post hole digger and put a series of holes about a foot,or more deep around the back where the cracks around where you under cut..then fill with concrete...

You're right. I have put too much work in the oven to not do it right (or at least better). I am going to pull back the rocks tonight then tomorrow dig and pour the piers. Man, this woulda been easier to do right the first time. I figured that since the foundation was going to be 24" deep, footers wouldn't be necessary. (the foundation is 4-5" chips and dust, 5" concrete with rebar, then two stacks of CMU to bring it up to level with the patio then back filled)

Thanks for the advise.

[thickstrings]

Re: Finishing firebrick chimney?

Is it possible to pull all the rock back? Then, undercut,dig, to the bottom of your slab, to expose the underneath of the floor....get a post hole digger and put a series of holes about a foot,or more deep around the back where the cracks around where you under cut..then fill with concrete...We are trying to put pillars under the slab, like legs...it may stabilize it....its not only the weight, but water run off down the sides of your fireplace that is washing out the allready marginal base..Just some work and a few bags of concrete mix......You can do the pillars one at a time, or make a mono pour and cap it all..Trying to put the geenie back in the bottle...Hard to tell without seeing it. Give it some thought, before winter..