I wish you the best solution for your dilemma.

It's called a floating floor for that reason - the entire area of vinyl plank can slide around a little bit. The usual way to deal with the gap at the edges is to use baseboard trim.

For your threshold you can get a bigger threshold, it may not match the vinyl plank perfectly but you can get something that closely matches it or at least something that looks good with it. Any home improvement or flooring stood should have a good variety of thresholds that are wider.

As for the second image, that gap it too wide for any sort of caulk and the best way to deal with it is to get thicker molding or staged molding using multiple pieces to build it out thicker.

There should be no transition between rooms when doing same floating floor throughout. Since you have a transition the best you can do now is to clean up all the caulk and fasten the transition directly to your subfloor. I would recommend finishing nails in center, so that nails don't hit the actual floor planks. You want that transition to be fastened without nailing the floor. There is no need to caulk any floating floor, so i would clean off as much if the caulk as i can. The second picture you should just trim out using a baseboard or even a 1x4 primed finish board then you can install quarter round or shoe moulding against the floor. Again, only nail trim to walls not the floor to keep the floating aspect. If you nail down floor with trim you might see some buckling/separation of planks as they expand/contract.

Have you read the installation instructions? They require room transitions depending on the room size to allow the floor to float properly.

My friend had a cheap contractor install a floating laminate floor in his entry way and large kitchen. No transition was used where it should have been and every summer the floor can’t expand far enough and pops up. It shrinks back down in the winter but more people should read instructions.

We don’t have enough info yet but don’t sweat this too much. It looks like caulk near the doorframe where the floor was cut a bit short originally but the floor has now shrunk a little more creating an even larger gap.

The threshold should be investigated more. Is there adhesive on both sides or just one side? It may be able to be cleaned and reset in place.

Yes, I have actually. Transitions are just covers for the required gap at ends. You will need one if you change direction of installation from room to room, run up against another type of floor, or just doing single room. The most issues stem from incorrect installation due to lacking expansion gaps, poor assembly by not locking planks correctly or nailing/caulking down sections of the floating floor. If you install the underlayment correctly and follow all guidelines for end gaps, including at doorways, dont nail or caulk any portions of floor down, you can run a whole house without a single transition without any issues. Also, different manufactures have different recommendation and I would not use a product that said you had to use transitions between all rooms, and have yet to see one that specifically requires this.

Your friends floor is likely an issue with no end gap allowances for expansion. Some contractors will install floor without pulling up baseboards to cut their costs and try to cover end gaps with shoe molding. Most floors require at least 3/8 expansion gap against any hard surface.

There already is a baseboard trim, it just doesn't go down enough so it's filled with caulk. I did slide it around a little so it does look better.

So there is baseboard there it just doesn't go down enough. So somehow get a little bit of baseboard to fill the gap after cleaning the caulk out?

Also the floor has an elevation change so I guess that's why there's a transition.

Quarter round or shoe molding where floor meets baseboard to cover up remaining gaps then.

https://imgur.com/gallery/EHStgih Looks like adhesive on just the floor. What is the name of this kind of caulk.

Okay I also don’t really have a subfloor to attach the transition too as seen in these photos .

https://imgur.com/gallery/EHStgih

Regardless of the subfloor, the transition usually comes with a metal clip rail. You can anchor that into the floor then the piece just snaps in. Looks like a tiny u channel and has little ribs to hold the paper transition.

They glued the transition strip to both sides of the floor which contributed to the failure. They also didn’t install the metal U channel to the subfloor in the gap between the floors of the two rooms for the floors to float freely.

The caulk is probably a white acrylic latex but you don’t want that. It acts like a glue a prevents the floor from floating.

Here’s a link to a product that best shows the metal U channel you’re missing.

https://www.homedepot.com/p/PERFORMANCE-ACCESSORIES-Warm-Stone-0-75-in-T-x-2-37-in-W-x-78-7-in-L-Laminate-4-in-1-Molding-M4IN1-05699/316754925

Okay so there is the metal u channel and the threshold is 2 separate pieces that are now stuck together.

Is there a way to buy a new threshold that has the same color as my current floor or should I just try to stick the glued together threshold into the uchannel?

It’s not stuck together. You have no metal at all and that’s why it was glued in place.

Technically you have a reducer moulding but the person who installed it did not do it correctly.

The metal u channel acts like a clamp to hold onto the center wood channel on the bottom of the transition strip/threshold/reducer moulding.

Moving forward, I wouldn’t worry about buying a new moulding. If you did install the U channel you would probably need to cut the floor to have the proper gap. I recommend just cleaning off the glue and then gluing it back in on just the taller floor side. While not perfect, it is good enough and will be better than you had before.

Thanks you so much. I’ll look for an acrylic glue.

You’re welcome. I like Liquid Nails construction adhesive. Just don’t use a “Gorilla Glue” type glue for this.

For the second pic do you have an example on what you mean? The moulding is coming up short so they filled the gap with caulk.

Sure, Something like these. Look at plinth blocks for the door, and/or using bigger trim with plinth blocks. For where the floor meets the wall thicker baseboard trim with shoe molding or quarter round. https://i.imgur.com/KC8uny1.jpg https://i.imgur.com/JW4bxV3.jpg https://i.imgur.com/US4KJ0B.jpg