Should flooring run straight through a doorway into the next room?

Continuous flooring looks better and makes a house feel bigger, but a floating floor has limits on how far it can run in one piece, and doorways are where those limits get tested.

Difficulty: intermediate
Time: 30 min
Read: 5 min

Short answer

Run it through if you can — it looks far better than a threshold strip at every door. But a floating floor expands as one sheet, so there is a limit to the area and the run length that can be continuous, and doorways are a pinch point. Beyond the manufacturer's stated limits you need an expansion joint at the doorway, covered by a T-bar.

A threshold strip in every doorway is the visual signature of a floor laid room by room. Running through reads as one continuous floor and is usually what people want. The constraint is not aesthetic — it is that a floating floor moves as a single object, and the bigger it gets, the more it moves at the edges.

What you'll need

the flooring manufacturer's installation instructions
a multi-tool or jamb saw for undercutting frames
T-bar or threshold profiles, if needed (optional)
spacers

Step by step

Read the manufacturer's maximum continuous area and run length.They state both, and they vary between products. Exceeding them without an expansion joint is the standard cause of a floor that lifts in the middle or buckles at a doorway.
Measure the whole continuous area, not each room.If the floor runs from a hall into a living room and a kitchen, that is one floor. It is the total that counts against the limit.
Undercut the door frame and architrave rather than scribing round.Cut the frame at the flooring height using an offcut on a piece of underlay as a gauge, then run the floor underneath. It hides the expansion gap and looks like the frame was built around the floor.
Keep the expansion gap at every fixed point in the opening.The frame legs, the stops, any threshold — each is a place the floor can be pinched. Space them all.
Check the run direction works through the opening.Boards should run in the same direction through the doorway, which usually means deciding the hallway direction first and letting the rooms follow.
Watch the width of the doorway itself.A narrow doorway between two large areas is a bottleneck: the floor there is only a couple of boards wide but has to transfer the movement of two big rooms. That is exactly where a manufacturer will want a joint.
Where a joint is required, use a T-bar fixed to the subfloor, not through the flooring.The profile's base is fixed in the gap between the two floor areas; the flooring is free to move under its wings.
Use a threshold strip anyway where the floors differ.Different materials, different heights, or a change from hard floor to carpet all want a proper profile — a ramp, a level joiner or a carpet-to-hard-floor edge, chosen on the height difference.
Check door clearances before laying, not after.Continuous flooring under a door means the door has to clear it in both rooms. Trim doors before the floor goes down if you can.

Tips

Where you must break the floor, a doorway is the least visible place to do it because the door line already reads as a division.
Running the same floor through a hall and into rooms makes a small house feel considerably larger, which is usually worth the extra planning.
Underfloor heating changes the movement picture — check the manufacturer's limits specifically for heated floors, which are usually tighter.
In a long narrow hallway, the run length limit can be reached before the area limit. Check both.

Common mistakes

Running a floating floor through several rooms with no expansion joints — The whole floor becomes a single sheet with a large amount of accumulated movement. It presses against the walls, cannot go anywhere, and lifts in the middle or buckles at the narrowest point — usually the doorway that connects the areas.
Pinning the floor at a threshold — A threshold strip screwed down through the boards fixes the raft at that point. Everything that expands towards it now has nowhere to go, and the same buckling follows.
Scribing the flooring around a door frame instead of undercutting it — It is fiddly, never quite neat, and leaves the boards touching the frame with no expansion gap — creating a pinch point at exactly the place the floor most needs to move.

If it doesn't work

Floor lifting in the middle of a large open area

Cause: Exceeding the continuous area limit, or pinched somewhere — Fix: Find and release every pinch point first — frames, thresholds, pipes, units. If the area genuinely exceeds the limit, an expansion joint has to be cut in and covered.

Boards buckled in a narrow doorway between two rooms

Cause: Movement from both areas transferring through the narrow neck — Fix: Cut a proper expansion joint in the doorway and fit a T-bar fixed to the subfloor.

Door catches on the new floor in one room only

Cause: Different subfloor heights either side — Fix: Trim the door, or use a ramp threshold if the height difference is significant.

Questions people ask

How big an area can a floating floor cover?

It depends on the product, and manufacturers state both a maximum area and maximum run lengths in each direction. Rigid core products often allow larger areas than laminate; heated floors usually allow less. The instructions with the floor are the authority, and they are worth reading before buying enough for a whole ground floor.

Can I glue the floor down to avoid the problem?

A fully bonded floor moves with the subfloor rather than as a raft, which changes the rules entirely — but only some products can be glued, and it requires a flatter, better prepared subfloor. It is a different installation method, not a workaround.

What about running from a room into a bathroom or kitchen?

Water is the deciding factor. Many laminates are not suitable for bathrooms at all, and the transition at the door is a sensible place to change material. A properly formed threshold there is a feature rather than a compromise.