It doesn't. You run a tack strip in front of the installed threshold, and stretch the carpet to the tack strip. Another possibility would be to "turn" or "tuck" and tack it (basically making a "sideways hem") right to the edge of the tile. One other way would be to use an "insert" strip. It's a channel strip with a tack edge that you stretch the carpet to, and then there's a vinyl "T" shaped insert that pops into the channel, and caps over the edges of the carpet and tile. ANY of those will work, as well as using a wood threshold instead of marble. My preference, though, would be for the marble threshold. But I'm kinda biased. :-)

Never assume a flooring installer will finish the transition to another kind of flooring. A tile-setter does not carry carpeting tools. Flooring installers don't trim the bottom of doors. These disclaimers are usually stated in fine print at the bottom of the proposal. I would have completed the transition, and trimmed the bottom of the door. I make sure that part is clearly stated in the proposal, and how much I'm charging for that. Usually 50 to $100 per transition, depending on how heavy the door is to take off. For this, I would use the thin metal floor reducer. Here are the anchors best suited for this application: Here is a link that might be useful: Hilti HPS light duty concrete anchors

You've had a Schluter edge put on a tile that needed a proper CARPET REDUCER. A REDUCER is just that. It REDUCES the height of the tile DOWN TO the height of the carpet. That's why they are called reducers. They are wedge-looking pieces that make this a non-issue. Your carpet/pad combination is not thick enough to handle the "L" you have. You will need to have a reducer added. It won't be pretty. The schluter "L" has been installed at the same time as the tile...which means it is sitting UNDERNEATH the tile. It will take some effort to change this. A decent tiler will handle this without much issue. Whomsoever made the original decision will pay for the change. That's how these types of change orders work in new builds. The reducer install will be much cheaper than removing the carpet and replacing the pad and then reinstalling it all.

"https://www.gardenweb.com/discussions/5839841/hardwood-and-tile-floors-both-squeak-after-transition-strip-replaced#n=2" Did you not see the answers from the other day? Post pics that may help as well.