This is one of those details nobody thinks about until the floor is down and there is a visible gap all the way around the room. It is not a mistake. It is deliberate, it is necessary, and how you cover it is a real decision with a real effect on how the finished room looks.
Here are the four options, in rough order of cost.
Why there is a gap at all
Floating floors — most luxury vinyl, all laminate, and a lot of engineered wood — are not fastened to the subfloor. They sit on top as one connected sheet and they move as a sheet, expanding slightly in humid weather and contracting in dry weather.
That movement has to go somewhere. Installers leave an expansion gap at every wall, typically around a quarter to three-eighths of an inch depending on the manufacturer's instructions and the size of the room. If that gap is pinched — by trim nailed down through the floor, by a heavy cabinet, by a doorframe not undercut — the floor has nowhere to expand and it peaks in the middle of the room instead.
Nailed and glued floors move less, but they still need a tolerance at the wall, because no wall in a real house is perfectly straight.
So there is always a gap. The question is only what covers it.
Option one: quarter round
A quarter round is exactly what it sounds like — a quarter of a circle in profile, typically three-quarters of an inch each way. It nails to the baseboard, never to the floor, so the floor can still slide underneath it.
It is the cheapest option, it is forgiving of walls and floors that are not perfectly flat, and it comes primed and paintable or in colors matched to common floors. If your baseboards are staying and the walls are a bit wavy, this is the workhorse.
The trade-off is visual. A quarter round adds a chunky step at the bottom of the wall, and in a house with flat modern baseboards it reads as an afterthought. It also collects dust along the top of the curve.
Option two: shoe molding, also called base shoe
Base shoe does the same job with a different profile — taller than it is wide, with a gentler curve. It projects less into the room and reads as part of the baseboard rather than a lump at the bottom of it.
It costs slightly more than quarter round and takes the same amount of labor. For most of the houses we work in, it is the better-looking answer for very little extra money, and it is what we suggest by default when the existing baseboards are staying.
If someone quotes you "quarter round" and you would prefer base shoe, ask. It is usually a small adjustment rather than a redesign.
Option three: pull the baseboards and reinstall them on top
The cleanest look available. Baseboards come off before the floor goes in and go back on afterward, sitting directly on the new floor with no additional trim at all. One uninterrupted line at the bottom of the wall.
It is also the most expensive and the most disruptive, and it carries real risk: baseboard that has been painted into the wall a few times over thirty years often splits coming off, and even when it survives you are looking at caulking and touch-up paint around the entire room.
It makes the most sense when you are already painting, when the baseboards are being replaced anyway, or in a room where the trim is modern and flat and a quarter round would spoil it.
Option four: undercut the baseboard
Instead of removing the baseboard, an installer cuts a slot along the bottom of it with a jamb saw and slides the flooring underneath. The gap is hidden inside the wall line and no extra trim is needed.
This works well with thin, hard materials and is common at doorframes and jambs, where undercutting is standard practice rather than optional. It is less practical along a whole room with thick flooring, with baseboards sitting hard against an uneven floor, or where there is no clearance to get a blade in.
Worth asking about, not worth insisting on. A good installer will tell you quickly whether your particular baseboards will take it.
Doorways and room-to-room: the transition family
Where the floor meets another floor rather than a wall, a different set of pieces does the work, and they are not interchangeable.
A T-molding joins two floors of the same height and, importantly, gives a floating floor room to move at the doorway. Long runs of floating floor through several rooms often need one whether you like the look or not.
A reducer steps down from a higher floor to a lower one — new luxury vinyl meeting older tile, for instance.
An end cap or square nose finishes a floor where it stops against something with no floor beyond it, like a sliding door track or a hearth.
A threshold sits at exterior doors and takes weather as well as feet.
And stair nosing finishes the top step, which is the piece that has to match your floor exactly and is the most visible of the lot.
Where this shows up in a quote
Trim and transitions are priced separately from the floor itself, usually by the linear foot with transitions per piece. On a whole-house job the linear footage is larger than people expect — every wall in every room, plus closets.
It is one of the most common things left off a low bid, which is why it is on the checklist in how to compare three flooring quotes. Ask for it as its own line so you can compare like with like.
One last thing: paint before, caulk after
New trim should be primed and painted before it goes on, or at minimum before the room is put back together — painting shoe molding in place, at floor level, with a new floor underneath it, is nobody's idea of a good afternoon.
Caulk the top edge where the trim meets the baseboard. Never caulk the bottom edge to the floor. That bottom gap is the expansion gap doing its job, and sealing it defeats the entire point.
If you are planning a floor and are not sure which of these your house wants, we look at it during the free in-home estimate — the baseboards, the doorways and the height differences between rooms all get measured along with the floor.
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