Laying laminate in a doorway is the part of the installation where most DIY jobs start to look amateur. The planks click together easily across an open room, but the moment the floor reaches a door jamb, casing, or threshold, the work changes. The doorway is a transition zone, and the floor has to pass through it without losing its expansion gap, without showing a visible cut edge, and without trapping the floating floor against a fixed frame.
This guide walks through the seven steps a professional follows to take laminate flooring through a doorway cleanly. The same logic applies whether the floor continues into a hallway, meets a different flooring type at the threshold, or simply ends inside the door frame. The steps are sequential, and skipping any of them creates one of the two outcomes that ruin a doorway: a visible gap around the jamb or a locked floor that buckles a few months later.
Why The Doorway Decides How Professional The Floor Looks
The doorway is the most visible square foot of any laminate installation. Every person who walks between rooms looks down at it. A clean doorway means the planks slide under the door casing with no gap and no transition strip interrupting the run. A poor doorway means a sliver of subfloor showing, a thick T-bar covering a bad cut, or planks pinched tight against the jamb with nowhere to expand.
The doorway also decides whether the floor survives. Laminate is a floating floor, which means it expands and contracts with humidity. If the planks are locked under a door jamb with no clearance, the entire floor in that room is anchored at one point. The first humid week of the year pushes the planks against the jamb, and the floor lifts somewhere else in the room — usually in the middle, as a ridge. This is why the expansion gap for laminate flooring matters as much under a door jamb as it does along the walls.
Two decisions shape every doorway installation:
The first is whether the floor passes through the doorway into the next room or stops at the threshold. A continuous run requires the planks to be slid under the casing on both sides of the wall. A stopping run requires a transition strip to terminate the floor cleanly.
The second is whether the door jamb gets undercut so the plank slides beneath it, or the plank gets notched to wrap around the jamb. Undercutting the jamb is the professional method. Notching the plank is the fallback when the jamb cannot be cut, and it always shows.
Tools And Materials Needed Before You Start
The doorway portion of the installation has its own tool requirements that go beyond the basic kit used in the open room. An oscillating multi-tool or a manual jamb saw is the single most important tool for this step — there is no clean substitute. A jigsaw with a fine-tooth blade handles the notching cuts on the planks. A pull bar and a tapping block move the final plank into place under the casing where a hammer cannot reach. Spacers maintain the expansion gap during the dry fit.
The full tool list for a laminate installation is covered in our guide on the tools needed to lay laminate flooring, but the doorway-specific additions are the jamb saw, a framing square for measuring jamb depth, and PVA Type II wood glue for the one joint that cannot be clicked together with the rest of the floor.
The flooring itself needs to be acclimated before any of this work begins. Planks brought from a cold warehouse and installed the same day will shrink after the room reaches its normal temperature, and the gap that opens around the jamb cannot be closed. The reasoning behind this is explained in our article on why you should acclimate laminate flooring, and the rule applies to every plank, including the ones that will sit in the doorway.
Step 1: Plan The Direction Of The Floor Before The First Plank Is Laid
The doorway is decided before the installation starts, not when the floor reaches it. The direction the planks run determines how the doorway is cut. If the planks run parallel to the door opening, one long plank will pass through the threshold, and only that single plank needs notching. If the planks run perpendicular to the opening, the ends of multiple planks will land in the doorway, and each one has to be cut and slid under the casing individually.
Parallel runs are easier in doorways but may not be the right direction for the room. Perpendicular runs are harder at the threshold but often look better in long, narrow rooms because the planks visually extend the length.
The starting wall also matters. The professional approach is to start the installation at the wall opposite the doorway and end at the door. This way the final row is the one that slides under the casing, and the cuts are in the most visible plank. Starting at the doorway wall forces you to slide the last plank backwards into a closed jamb, which is mechanically much harder.
Step 2: Decide Whether The Floor Passes Through Or Stops At The Doorway
This decision changes everything that follows. If the laminate continues into the next room as a single floating field, the planks have to slide under the casing on both sides of the wall, and no transition strip is used. If the floor stops at the doorway because the next room has tile, carpet, or a different laminate, a transition strip terminates the run.
Continuous runs look better but only work when the next room is also laminate, the doorway is wider than the manufacturer’s tolerance for a single floating field (usually 40 feet in any direction), and the subfloor heights match. Most manufacturers actually require a T-molding in any doorway narrower than 4 feet because the pinch point at the jamb counts as a constriction in the floating field, and the floor needs a movement break there.
Stopping runs use one of several profiles depending on what they meet. A T-molding bridges two laminate floors at the same height. A reducer bridges laminate to a lower floor like vinyl or thin carpet. A threshold or end cap finishes laminate against a fixed surface like a sliding door track. The full breakdown of these profiles is in our guide on the different types of transition strips, and choosing the wrong one is one of the most common doorway mistakes.
Step 3: Undercut The Door Jamb And Casing
This is the step that separates a professional install from a DIY one. The door jamb and the casing trim around it have to be cut horizontally so the laminate plank can slide underneath them. The cut height is the thickness of the plank plus the thickness of the underlayment, with no extra clearance — the plank should pass under tightly enough that no gap is visible, but loosely enough that it is not pinched.
The technique is simple. Take a scrap piece of the actual laminate and a scrap of the underlayment that will be installed under it. Stack them on the subfloor next to the jamb. Lay the oscillating multi-tool or the jamb saw flat on top of the laminate scrap, with the blade against the jamb. The scrap is now acting as a height gauge. Cut horizontally through the jamb and through the casing on both sides of the wall. The cut piece of jamb falls away and leaves a slot the plank can slide into.
The casing usually extends past the jamb on both sides of the wall, so the cut has to continue through the trim on both faces. If the baseboard runs into the casing, the cut also has to extend a couple of inches into the baseboard to give the floor room to expand sideways. After the cut, vacuum the slot thoroughly. Any sawdust or debris will hold the plank up off the subfloor and create a visible bump in the floor.
If a jamb saw is not available, an oscillating multi-tool with a wood blade is the modern equivalent and easier to control. A handheld pull saw works in a pinch but takes longer and is harder to keep level. Trying to do this cut with a regular handsaw or a circular saw almost always damages the jamb.
Step 4: Measure And Mark The Plank That Will Pass Through The Doorway
With the jamb undercut, the plank itself has to be measured. Slide a framing square or a tape measure under the cut jamb until it hits the wall stud or the back of the casing. This measurement is the depth the plank needs to be tucked. Measure both the inside of the jamb and both sides of the casing, because the casing usually projects further from the wall than the jamb does.
Transfer these measurements onto the plank, working with the plank in its final orientation. Mark the cut with the visible face of the plank facing down — jigsaws, coping saws, and circular saws all cut on the upstroke, so any chip-out happens on the side facing up. With the visible face down during the cut, the chip-out lands on the back of the plank and never shows.
If the plank runs parallel to the doorway, the cut is usually a long shallow notch along one edge. If the plank runs perpendicular, the cut is an L-shape or a stepped notch on the end. Cardboard templates speed this up when several doorways have the same casing profile — cut the template once, trace it onto each plank.
Always leave the manufacturer’s expansion gap (typically 8 to 12 mm) between the cut edge of the plank and the wall stud at the back of the slot. The plank does not need to go all the way to the back of the cut; it only needs to go far enough that the visible portion of the cut edge is hidden under the casing.
Step 5: Cut The Plank With A Jigsaw
A jigsaw with a fine-tooth or laminate-specific blade gives the cleanest cut for notching. Clamp or hold the plank firmly with the visible face down. Cut slowly and let the blade do the work — pushing the saw forces the blade to flex and produces a wandering cut that may not fit cleanly under the casing.
For straight rip cuts, a laminate cutter or a circular saw with a fine-tooth blade is faster. For the curved cuts around door hinges or unusual casing profiles, the jigsaw is the only practical tool. A coping saw works for very small notches and gives complete control, but it is slow.
Test fit the plank dry before committing. The plank should slide under the casing with light hand pressure, sit flat on the subfloor, and leave the expansion gap at the wall. If it binds, mark where it binds, lift it out, and trim a hair more. Forcing a plank that is slightly too wide will either crack the plank or push the jamb back out of position.
Step 6: Lock The Notched Plank Into The Floating Field
Most modern laminate uses a click-lock joint, where the tongue of one plank is angled into the groove of the next and dropped flat to lock. The trouble in a doorway is that the notched plank cannot usually be angled — the casing above it prevents the angle motion. The standard fix is to remove the upper lip of the groove on the previously installed plank using a chisel or a planer, so the notched plank can be slid in flat instead of angled.
Once the upper groove is removed, the notched plank slides in horizontally under the casing. Because the click joint is now disabled at this single seam, a thin bead of PVA Type II wood glue along the joint replaces the mechanical lock. The two systems behave differently — the difference between them is covered in our article on click-lock or tongue-and-groove laminate flooring — but the glued joint is just as strong once it cures.
Use a pull bar to draw the plank tight against its neighbor on the side that cannot be reached with a tapping block. The pull bar hooks over the far edge of the plank, and a tap on the upright leg pulls the joint closed. Tap gently. A heavy hit cracks the click joint or chips the visible edge.
Step 7: Install The Transition Strip Or Reattach The Casing
If the floor passes through the doorway as a continuous run, the work is done as soon as the casing slot is filled and the joint is glued. Wipe off any squeezed-out glue immediately with a damp cloth — once it cures, it can only be removed by sanding. Pop the casing back if you removed it, or leave the cut casing in place if it was undercut without removal.
If the floor stops at the threshold, the transition strip goes in next. The strip’s track screws into the subfloor in the gap between the two floors, never into the laminate itself. Screwing the track into the laminate locks the floating floor at that point, which causes the same buckling problem as failing to undercut the jamb. The track sits in the gap, the strip clips or screws into the track, and the laminate slides freely underneath.
Walk the doorway from both sides. Look for any sliver of subfloor showing, any gap between the plank and the casing, any rocking when weight shifts onto the threshold. A clean doorway has no visible cut edges, no light showing under the casing, and no movement in the plank when stepped on.
Common Doorway Mistakes That Show Up Later
Three mistakes account for almost every failed doorway. The first is skipping the jamb undercut and notching the plank tight to the jamb instead. This always leaves a visible gap, and the gap gets larger as the floor expands and contracts.
The second is forgetting the expansion gap behind the casing. The plank slides in, the casing hides the cut edge, and the floor looks fine for the first few months. Then humidity rises, the floor expands, and because there is no clearance behind the casing, the plank pushes the floor up somewhere else in the room. This is the same problem covered in our guide on why laminate flooring expands, and the fix is always to lift the floor and recut the gap.
The third is using the wrong transition strip or screwing it into the laminate instead of the subfloor. The strip becomes an anchor point, and the floating floor is no longer floating. Damage shows up as gaps at one end of the room or buckling at the other end.
When The Doorway Is Beyond DIY Range
Some doorways are harder than the seven-step process can handle. Doorways with stone or tile thresholds that cannot be undercut force a notched-plank approach with a metal transition profile. Hallways with multiple doorways close together create inside corners that a standard jamb saw cannot reach. Older homes with thick layered casings (sometimes three or four passes of trim) require partial removal and reinstallation rather than undercutting.
If the installation involves more than two doorways, an out-of-square frame, or a transition between three different flooring types, the time and tool cost of doing it right usually exceeds the cost of having a flooring contractor handle the doorways while the open-room work stays DIY. The doorways are the part of the floor that gets noticed, and a clean job there carries the rest of the room.
