WHere is the threshold strip supposed to go? (2024)

OK thanks. That means I need to ensure the vinyl (and ply subfloor) extend very slightly under the door. Some nibbly ply cutting for me.

You have 2 choices - Narrow threshold strip which just goes underneath the door as commented on above.
The second choice is to have a threshold strip which is the full width of the door casing - depending on how the new floor coverings are pattened or finish that may be a better choice for you.
The Threshold strip should finish the same thickness (height off the floor) as the carpet and underlay. That you may not yet know - 5/8inch is a good starter...

W

OP,
Stick with the 40mm to 50mm wide transitions - the wider pieces or custom made thresholds are not needed for carpet to vinyl.

Your diagram is wrong - the red vinyl should have stopped at the reveal: you have taken it beyond. The green carpet should go up to the transition - the transition strip is butted up to the door stop.
It can be a stuck or planted stop but you butt the transition strip up to it.
The door will close over it as described by dazlight above.

Running the vinyl past the stop is no big deal because its thin vinyl, and the transition could sit on it & butt up to the stop.
But I always try to have the "meeting line" at the reveal in your sketch.

There are variations for different materials and reducers/adaptors/transitions & customised thresholds available but you have a straightforward job.

vinn said:

OP,
Your diagram is wrong - the red vinyl should have stopped at the reveal: you have taken it beyond. The green carpet should go up to the transition - the transition strip is butted up to the door stop.

Click to expand...

OK that's definitely simpler. I thought the transition strip would have to sit on top of the edge of the vinyl (and carpet), to stop it from peeling up...

I didn't explain myself very well above.
Its best for the vinyl to go under the edge of the strip so that the raw edge i covered.

Note that the jambs and stops are typically undercut to allow the flooring materials, such as vinyl or laminate, to be slipped under the jamb/stop and covered.

vinn said:

Note that the jambs and stops are typically undercut to allow the flooring materials, such as vinyl or laminate, to be slipped under the jamb/stop and covered.

Click to expand...

Hmm, maybe in new houses. Not in old ones.

vinn said:

The floor fitter is the one, in new or old property, who cuts the jambs

Click to expand...

Ah, I saw that in an American carpet fitters video once. Never seen it done in a British house yet though...

No, skirting is lifted and placed back over the flooring edge & the expansion gap. Although I have seen skirting undercut for laminate and solid woods instead of lifting the skirting above the raised FFL.
There can be consequences.

If the skirting is left in position then a scotia bead is typically used as a cover in lieu of skirting.

Some fitters do cut corners and stop vinyl at the skirting but its a bad practice that first class work wont tolerate.
Vinyl is, of course, laid and fixed in a number of ways - fully stuck down sheets have very little movement.
No matter, as above, the jambs are undercut for slipping flooring material underneath.