The bevel on the marble transition is to minimize the chipping that might happen on a square edge. Plus it's just more pleasant to step on instead of a sharp stone edge. The threshold is traditionally supposed to come about 1/4" above the floor (you might need to trim your door a tad) to hold back water on the floor; many more contemporary types have it flush with both types of flooring, which is more decorative than functional. You may have to cut back that first board so that the marble threshold will fit, I'm not sure.

HOWEVER, you can go to any granite/marble fabricator and have them custom cut you a threshold that doesn't have the bevel, or is only beveled on one side, or slopes, or does anything your heart desires.

Another option is to use a wooden threshold, which is just fine - if you get a flood and the threshold gets nasty, pry it out and put down a new one. Seal the edge of the wood floor under the threshold thoroughly with silicone. I think you need what is called a T molding.

Sorry for the hijack, but to johnmari and anyone else...can you use a marble threshold between porcelain tile and carpet? Our carpet doesn't look good at the edge of the new tile. The carpet is Berber (6 years old) if that matters. We will eventually pull it up but I can't think about it now. Thanks!

Susan ~

Susan, we have carpet-to-tile in the master, although it's not berber. The carpet and tile both butt up tightly against the marble threshold. Is the problem with your transition the appearance of the tile edge or the carpet?

Doesn't matter. You can use either a marble OR (for the OP's benefit) a wood threshold between tile and ANY other flooring material.

The marble is thick also, is it meant to be a "bump" in the floor? I just cannot see it being flat to the tile and wood floor

Although many people do request that a marble threshold be flush with their floor on atleast the bathroom side, this is actually wrong. Johnmari is right. The whole reason why marble thresholds used to be REQUIRED at all bathroom doors was to provide a small dam at the doorway to guard against minor flooding, from say, kids splashing in a tub, or a minor toilet overflow.

Mowers-- you're doing fine. You were right to install that plywood. What you had before wasn't NEARLY enough, and what you've put down now brings it up to where it should be. One thing to think about-- instead of using 1/4" CBU, what about using Ditra instead? It's only 1/8" thick, as opposed to the 1/4" of the CBU, and it'll provide alot more protection against movement to your floor. As for the heating mats, I don't see a problem with that, either (OVER the Ditra, not under). About the only thing you'll have to do is undercut your bathroom door, and maybe use a flange extension on your toilet flange, if it's already set.

Thanks..

Bill, I took up your suggestion and will try Ditra. Wow though, I purchased a roll at Home Depot, expensive at $69 a roll!!!

One point of mystery to me though. I says on wood floors to use modified thinset under the Ditra, OK, so I got some Flexbond by Custom. But then it says for the top of the Ditra for adhering the tiles to, use UNmodified thinset. This confuses me...what if you are installing porcelain, don't you need a "flexbond" rated type thinset????

What do I do at the door...how far should the marble threshold go into the door jamb area...half way, all the way, etc. I am not sure here. As shown in my picture, there is a greyish colored section of hardwood floor, this is where the old marble threshold sat. Is this the correct place for it with the new floor? And if so, do I extend the Ditra over the grey wood section? Will it "stick" correctly? And how to I avoid the sandwich look when you look at the room from the outside, won't I see, thinset, a Ditra mat, some thinset, and then the marble threshold. If I end the Ditra inside the room, will the marble "stick" to the top of the hardwood floor correctly.

Cannot answer those questions...but in regards to the electric mat...how do you put in on top of the ditra...is has those squares all over the place...do you need to fill it first

You may want to call Schulter (spelling?) and ask them if the experts do not chime in here.

mowers-- that's no mistake. On top of Ditra, you use unmodified. With Custom's thinsets, it would be Master Blend that you want. I had the same skepticism the first time I used it. I got guarantees from both the owner of tile-experts. com, where I bought the Ditra from, as well as my area Schluter rep, that if any problems aros as a result of loss of bond from the unmodified thinset, that they'd back the installation. I've done more since then than I can count and not a single problem.

Also, as for the price, if you price out the same footage in cement board, you'll see you're not paying that much more for the Ditra, and getting alot more in return for your money.