Redoing Hearth - Want to lower it

[Firecozy]

My hearth had some ugly plain white tiles that I removed down to the concrete sub hearth. I will put new tiles over it or maybe a single slab piece but ideally I'd like to have the finished surface flush with the surrounding hardwood floor.

The concrete sub hearth currently sits just slightly above the floor level. From the basement I can see that the sub hearth is wedge shaped and one test hole told me even towards the edge it is more than 2-3 inches thick.

What I want to know is whether I would be opening up a can of worms if I just got Bull Dog Hammer Drill to try and take it down an inch or two. Then poured some self leveler to get my flat surface to put my hearth onto.

Other info that might be pertinent is that this is a 1908 house and I have no way of knowing whether this is original concrete or not. The area is 18 inches by 60 inches.

Otherwise, I understand I will need to use the self leveler anyway, and will want to make it as thin as possible so the hearth isn't raised up very high.

Do you think Bull Dogging it will be too much work? I would think the most work would be along the edge of the fireplace where I would need to probably use a grinder.

Any suggestions or tips would be much appreciated.

 

[begreen]

In an old house it's possible that once you get down a couple inches that the core of the hearth is rubble fill. At least ours was. I would want a decent thickness of cement on top of that.

 

[bholler]

Yeah it might work or you might end up pouring a new hearth completely There is only one way to find out

 

[therdlesstravld]

Plastic off an area around it and take a diamond cup attachment on a grinder and bring the whole thing down. You'll be able to get it pretty even (perfect if you run string lines across and follow them). Either way you can get it level enough to pick up the rest in the thin set for the tiles or slab.

 

[delp]

I tore my old hearth completely out. I had a cracked 2 ½" thick solid piece of slate sitting on 9" of rubble. I attached angle iron to the hearth framing as well as to the 3 sides of brick wall below the firebox, set some steel decking on that, poured cement (about 7" thick) and left it about 1" below the level of the surrounding wood floor and then set ¾" saltillo tiles. I weigh about 106lb when I inhale and am soaking wet. It was a ton of work and a huge mess. But, so glad I did it, looks great and I know there are no combustibles below the hearth or below the firebox. I used a hammer drill to break up the already cracked slate hearth and I think it took something like 10-12 5gal buckets to empty out the rubble…found ancient marbles, old pencils, old newspapers, a entire freaking archive of stuff from way back when; house is 1896.

Can you put a picture up of what you can see from the basement?

 

[Firecozy]

Ok, steps 2 and 3 are now done. I think I got a little lucky but also one of my fears came true. I used a roto hammer and found what I think was a seam about 2 inches down. My guess is that the hearth used to be brick and someone poured concrete on top of the old sub-hearth. So even though it was still a bit of grunt work, I could roto hammer along that seam and get a number of large chunks to come up.

My fear was causing some secondary damage from the impact and vibration of the roto hammer. I was also concerned about where the subhearth connected to concrete beneath stove and brick surround. Sure enough I got some damage on the concrete floor of fireplace beside the stove that I will have to patch. Sorry I don't have photos, so hopefully that's clear.

I did not find any rubble but maybe that is a bit further down. So following getting it all to about 1.75 - 2 inches below floor, I poured a thin layer of concrete prior to using the self leveller. In hindsight, I should have used cement or maybe build it up a bit higher. There are a couple of high spots where cement does not work because you end up with gravel and no binder.

So the next step is to pour about a half inch of self leveller over concrete. But I'm concerned about getting this right so in the end my tile is flush with floor. The area is small, only 18" x 68", but if the floor is not level, and I use self leveler, then it won't match from one end to the other.

I also don't know how much to account for the thickness of the thinset. If I use a 1/4" trowel at an angle, I'll get maybe 1.8" of thinset thickness, but then doesn't that compress a little bit once the marble tile is set into it? Any experienced tilers out there? I've heard cardboard thickness used as a rule of thumb, which is probably about 1/8".

 

[delp]

hearth folks sent me over to the john bridges forum. all things tile all day, every day (great site):

http://www.johnbridge.com/vbulletin/forumdisplay.php?f=1

 

[therdlesstravld]

You can always mix the thin set to be more dry and put more underneath the tile until its level with the surrounding floor. Your going to be more concerned with everything being flat and not having lips rather than level.

Id get the whole area within the tile thickness + about 3/8". Then mix the thin set to a thick peanut butter consistency (you'll need a corded drill preferably a 1/2" drill) and trowel out the mix on the ground. Then back butter the tile and lay it. If it's not high enough then build up the thinset on the ground. You'll get a feel for how much your going to need each time. The dryness of the thinset will be very helpful in making sure the tiles don't settle.