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Fropitar 05-24-2010 04:38 PM

Removed tile around fireplace, drywall underneath?!
First let me start by apologizing if this is the wrong forum.

I'm a new home-owner and have decided to replace the old white ceramic tiles around my fireplace with some slate tiles I received from a family member. The fireplace is one of those "fake" fireplaces, with a gas line and ceramic logs in it. It is constructed of metal and seems as though the whole unit is screwed to the framing around it. Behind the ceramic tiles was DRYWALL. Of course when ripping out the old tiles, the drywall became a bit ripped up so, my question is as follows:

Is drywall acceptable to thinset slate to? Can I leave the ripped up drywall? If not should I replace it with drywall or cement backer board? Any other suggestions that I have not thought of would be greatly appreciated as well.

Here is a picture:

Bud Cline 05-24-2010 06:14 PM

Patch the drywall with joint compound, prime it with a paint primer, go again with the slate using modified thinset mortar. In this case you should be just fine.

Fropitar 05-24-2010 09:00 PM


Originally Posted by Bud Cline (Post 446563)
Patch the drywall with joint compound, prime it with a paint primer, go again with the slate using modified thinset mortar. In this case you should be just fine.

Thanks bud. This will be my first time tiling, what do you mean by a modified thinset? Im assuming there is a special thinset for laying tile to drywall/joint compound?

Bud Cline 05-25-2010 12:43 AM

In this case you will have a lot of surface patching if you use joint compound to fill and repair the damaged drywall. That's the way I would do it and that won't hurt anything but thinset doesn't like to stick to raw drywall patch material to well so I would suggest you first seal the patching with paint primer. Let that dry over night then use modified thinset mortar for the tile. Modified thinset mortar is the thinset mortar that will have additives already mixed in the bag for you as opposed to unmodified or dryset mortar. Thinset mortars come basically two ways; modified and unmodified. It should be fairly clear on the bag.:)

Fropitar 05-25-2010 05:47 PM

Ahh, I see. Thanks a million :)

Bud Cline 05-25-2010 06:31 PM

I should also caution you that thinset will not stick to the metal face components of the fireplace very well. Technically you can't use thinset on metal surfaces. But again, and in this case, you'll be OK if you do what was done previously and have enough tile attached (with thinset) to the wallboard to hold the tile. This will allow you to at the same time overlap the metal surfaces and it will work. Use thinset on the metal as was done before but it won't be dependable forever. Won't matter tho.:)

Fropitar 05-26-2010 03:52 PM

Thanks much for that important tip! Will do! I suppose I'll keep this tread up to date w/ pics and such as I go along for anyone else that might be doing a similar project.

Here is another Q for you:

the fireplace doesn't quiet sit flush with the drywall (no wonder it had extra grout on the sides of the tiles, they must have laid thick thinset to counter this problem). Would you suggest filling in the difference with joint compound? Or would you leave the offset and lay thicker thinset as they did before?

Here is a pic of my current joint compound job and of the offset (pre-sanding):
EDIT: The offset is probably about 1/8"

Bud Cline 05-26-2010 09:36 PM

Hey the "patch job" looks pretty good!

The fact that the fireplace ("can") isn't flush with the wall surface is an all-too-frequent problem. There's a couple of things you can do.

The first thing I would try is to move the can. If you can find the screws that hold the fireplace in place take them out and bump the can backward into the wall. There should be flex-enough in the gas supply to do this. Unfortunately bumping the can isn't always possible.

The next possibility would be to add a piece (pieces) of 1/4" cement board to the wall. This will reverse the error but this time in your favor. If you do this I would recommend using Hardibacker. Find the studs in the wall and screw the Hardi to the studs everywhere you can. This will also create a 1/4" edge around the outer edges to deal with but that is caulk-able.

The problem with just using more joint compound to fill with is that you will undoubtedly create a sloping wall surface and that's not a good thing. That would cause serious lippage at the corners. I wouldn't do it that way.:)

One more fix would be to use masking tape and apply it to the wall where the old line is. Place the tape on the painted wall surface to the left of the firebox. Then, use modified thinset and a 1/4" X 1/4" notched thinset trowel to apply thinset to the now filled/repaired surface. Be sure to prime the joint compound first as discussed earlier. After your combed out pull the masking tape off for a good straight edge on that side. Comb out some nice straight ridges and grooves then leave it sit over night. The next day you can use sandpaper and a wood sanding block to sand the combed thinset down to the required thickness. Don't sand too much so as to create a taper back to the wall surface.

Now you have a good solid 1/8" fill. One more time, apply more thinset to the sanded surface, this time using the flat side of the trowel. This will fill the ridges you created the first time around. Now you are ready for tile. The surface is flush and the standoff you have create is caulk-able. Now your tiles should easily overlap the can and be straight and flat.

That picture is a huge benefit for sure.:)

As you can see...moving the can could easily be the lessor of the evils.:)

Fropitar 05-27-2010 10:32 AM

Alright, after unsuccessfully attempting to move the firebox back and much debate, I've decided to go with raising the thinset, then sanding it down.

This morning I did some heavy sanding, and masked the "can" and walls:

Then I proceeded to lay a coat of primer down. I decided to scruff the metal up and primer the section that would have tile layed across it. I assumed (oh-oh) that it would help the thinset stick better than it would to a metal surface.

Here is what that looks like after the first coat:

Now to wait..

Bud Cline 05-27-2010 12:57 PM

Did you comb ridges into the thinset on the first coat?:) I can't tell from the picture.:)

Fropitar 05-27-2010 04:06 PM

I have yet to lay any thinset, I've just returned from the store and purchased a bag. I'm waiting for the 2nd (and last) coat of primer to dry. So basically I need to "comb" on a layer of thinset, let it dry over night.. after it dries I sand it with a blocksander until it is flush with my fire box.. after I have sanded it flush and it looks right, I then (clean it off) then fill in the dried combed area and let that dry, leaving me with an entirely flat and flush service to thinset my tiles to, right?

Bud Cline 05-27-2010 04:28 PM

Exactly correct. By building ridges and then sanding them it is much much easier to sand and get to the desired size (build out) when you only have the ridges to deal with. Thinset will sand easily if you do it in the first couple of days after application. Then-n-n-n-n-n, fill the low spots and you're ready to go.

This is also a good technique when attempting to use thinner decorative tiles with thicker field tiles. I apply the thinset to the backs of the tiles in that case one day, then sand them the next day and install them in more fresh thinset.:)

Fropitar 05-27-2010 05:56 PM

Whew, WELL... my first time working with thinset wasn't the greatest experience. At the start I was a bit shy and timid. Towards the end I started to flow a bit.. Surely it is something that takes years of experience to perfect. Hopefully this poor job holds up well enough for me, and perhaps even provides you with a bit of a laugh for the evening, lol.

Here is a picture.. sigh:

EDIT: The best part was knowing that I'm going to sand it down. With that in mind it let me get a little more loose than I would have if I were laying the tiles down.

Bud Cline 05-27-2010 06:39 PM

1 Attachment(s)
PERFECT! Looks good!

There's nothing wrong with that!

Tomorrow sand the tops of the ridges flat and
on-plane" with the proud metal surfaces, don't get over zealous with the sanding. The bigger the sanding block the better. Filling the grooves with thinset will be much easier.

When the time comes to install the tile and you are spreading (combing) that thinset try to spread it all in one direction. Doesn't matter which way you go. The purpose for that is so that the high spots will collapse into the low spots when you place (squish) the tile and will result in almost a 100% coverage of thinset-to-tile-to-substrate. 100% coverage is your target, 85% is acceptable. In reality you'll probably get about 95% coverage.:) Don't anguish over it!

Another little tip.
Immediately prior to spreading the thinset for the tile application, use a wet sponge to wipe the substrate and the tile-backs thereby removing any sanding or transit dust and introducing some moisture into the substrate. This will give you a better bond and slow the leaching of the moisture from the fresh thinset into the substrate. In fact, I always have a bucket of water and sponge at my side to keep things clean and to moisturize the cementitious substrates.

Whoops almost forgot a critical move. You will have to install a temporary lentil/ledger across the top of the firebox to support the top (horizontal) tile row until the thinset seizes the tiles. You can use anything for a straightedge that can be screwed into the framing behind the drywall.

Don't forget you'll need spacers to stack the rest of the tiles tiles. The tiles won't stay in place on their own.

You will also note that the tiles probably won't come out even as far as spacing across the top of the firebox. I would determine where I wanted the leg-tiles to stack up then place the top row tiles one left one right one left one right to match the leg stacking, and finally cut the center tile to fit whatever space you have available.

Fireplaces are generally tiled from the top down in a case such as this.

WOW, that got longer than I expected it would.:)

Fropitar 05-27-2010 07:45 PM

Wow top down. So from the sounds of it, i'll need to stall a temporary ledger after every row?

EDIT: Also, which pattern would look more professional?

The tiles are 12x12's.

Pattern 1:


Pattern 2:

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