I built a surround, mantel and overmantel using MDF, various moldings and honed travertine tiles (filled). I don't know how to post pictures, but, if you e-mail me I'd be glad to send you some. To answer your questions: You can install the travertine directly on the drywall using fortified thinset (don't buy the pre-mixed kind). Just make sure the drywall is well anchored, I drove some extra drywall screws into the studs before installing the travertine. I didn't seal my tiles, but, the honed finish is smoother than what you have. The reason to seal before grouting is that the sealant acts as a grout release and makes it easier to clean the grout from the tiles. With rough tiles I've found it helps to keep a water spray bottle handy which you can use to flush out any grout that gets in the holes before it sets. 1/8" spacing is good, however, if your tiles have rough edges you may have to go to 3/16". On the hearth you need plywood for strength and then you should put down some wonderboard or hardiboard. This is because code usually requires at least 1" of non-combustible material on the hearth (check your local code to be sure what the requirement is). You meet the requirement by calculating the thickness of your tile plus the thickness of the thinset (1/8' - 1/4") plus the thickness of the cement board. You should err on the high side. Hearths can get pretty hot, so the thicker the non-combustible layer the better (it acts like an insulator). Also remember to check your local code on the required clearances from the firebox opnening to the mantel and surround. In most jurisdictions this is 12" (for non-combustible materials). I used some corbels that are closer but I bought some made out of molded stone that are non-combustible.

This is an old thread. I would stay away from Travertine! Might look cool, but really hard to clean. If you are one of the unfortunates that inherited this merciless product from a previous owner, last night a miracle happened. https://www.houzz.com/discussions/my-lemon-cleaning-miracle-excess-lemons-dsvw-vd~2892619

You should read that thread. All it took was lemons to clean the soot. The pits are not cleanable, and will soon be filled with a light beige/cream grout. Lemons are the easy go to for cleaning this awful stuff.

I built this fireplace years ago. Most of the large wall is drywall except around the fireplace itself. The fireplace will dictate where non combustable materials need to be used. That is a key rule to follow.

Vancouver Fireplaces by John Whipple · More Info

The tile is 1'x3' Travertine. We did a burn test of the fireplace prior to installation and noticed that the tile change ever so slighty in colour. I think it was the epoxy fill used to even out the Travertine's appearance.

The hottest spot on a fireplace is about 7" above the unit - dead center. This is where we rigged up the test tile for the burn test.

Prior to that I bake a few off cuts in my wife's oven. This went over like a ton of bricks.

I built this fireplace the same year. Except we had a larger budget so I order slabs of Travertine and not tile.

Contemporary Living Room · More Info

This fireplace is a gas unit and the heat is much lower than the real fireplace above this one.

The backing for these two fireplaces where different. The top fireplace saw drywall and cement board. No paint. No drywall mud. Just plain board.

The second fireplace we built with 3/4" plywood. Building paper and diamond lath.

Using an old wall with drywall mud and paint is not a good idea.

Hi, I had textured travertine put on my fireplace and have regretted it every since. I would like to put a natural textured travertine mantle, legs and trim on. My question is, can you attach the mantle to the existing tile or is that a bad idea? Here's a photo of existing fireplace and my preference.

preferred