A gap opening up between your luxury vinyl planks can look like a sudden failure, especially when it appears out of nowhere in a floor that was flat and tight for months. Before you assume something went wrong with the installation, it helps to understand that vinyl plank flooring moves with its environment, and some of what you're seeing is the material behaving exactly as designed. This guide covers the environmental, installation, and material factors behind gaps, how to tell a normal gap from a warning sign, and what to do about each.
What causes gaps between LVP planks? Gaps between LVP planks result from three interconnected factors: humidity and temperature swings that make vinyl expand and contract, installation errors such as insufficient acclimation or incorrect wall spacing, and the inherent thermal sensitivity of vinyl compared to other flooring materials. Identifying which factor applies to your floor determines whether the fix is mechanical, environmental, or professional.
Ace Handyman Services works with homeowners at every stage of a flooring project, whether you're trying to diagnose an existing gap problem or planning a new installation and want the acclimation and subfloor prep handled correctly the first time.
Quick Overview: Diagnosing and Addressing LVP Gaps
- Identify where the gap appears: at the wall, between plank ends, or along the long side seams.
- Measure the gap width against the 1/16 inch acceptable threshold.
- Check for accompanying symptoms like cupping, buckling, or a soft spot in the subfloor.
- Trace the likely cause: humidity swing, missed acclimation window, installation spacing error, or direct sunlight exposure.
- Attempt mechanical closure for small end gaps where the click-lock is still partially engaged.
- Address the root environmental or subfloor cause so the gap does not return.
- Call in a flooring professional if gaps are wide, recurring, or paired with moisture signs.
Understanding Normal vs. Problem Gaps in LVP
Not every gap in a vinyl plank floor signals a defect. Acceptable expansion gaps at walls and transitions typically measure around 1/16 inch and are normal material behavior as vinyl responds to seasonal temperature and humidity changes. Problem gaps, by contrast, exceed 1/8 inch, appear suddenly, or come paired with cupping, buckling, or a substrate-level opening that suggests a subfloor issue rather than simple expansion.
A floating floor needs room to move, so small, uniform gaps hidden behind baseboards or transition strips are expected and require no action. What deserves attention is asymmetry: gaps that grow in one room but not another, gaps that widen week over week, or gaps that appeared shortly after installation rather than developing gradually with the seasons.
Signs a Gap Warrants Closer Inspection
Watch for gaps wider than 1/8 inch, gaps at multiple seams in a concentrated area, visible movement when you walk across the plank, or a musty smell near the affected boards. These point toward installation error or moisture intrusion rather than routine thermal cycling.
The Three Primary Gap Causes: Environmental, Installation, and Material Factors
LVP gaps result from three interconnected factors: moisture and temperature changes in the environment, improper preparation and installation methods, and the inherent thermal expansion characteristics of vinyl itself. Each cause has a distinct prevention strategy and a distinct remediation path, which is why an accurate diagnosis matters before you attempt a fix.
Humidity Fluctuations and Seasonal Moisture Absorption
Indoor relative humidity below 30 percent or above 50 percent triggers measurable contraction or expansion in vinyl plank flooring. Winter heating dries indoor air and pulls moisture out of the planks, causing them to contract and open small gaps at the seams. Summer humidity does the opposite, pushing planks tighter together and sometimes causing them to bow slightly at pinch points. A hygrometer placed in the room gives you an actual reading rather than a guess, and a humidifier or dehumidifier can hold the space closer to that 30 to 50 percent band.
Improper Acclimation and Pre-Installation Preparation
Why is my LVP coming apart at the seams? Vinyl plank flooring installed without proper acclimation has not reached thermal and moisture equilibrium with the room, so the planks continue to expand or contract after installation, pulling seams apart at the locking joints. Manufacturers generally call for planks to sit unopened in the installation room for 48 to 72 hours before laying them, allowing the material to settle at the room's actual temperature and humidity.
Subfloor condition matters just as much as acclimation timing. A moisture reading above 12 percent in a concrete or wood subfloor, a leveling tolerance worse than 1/8 inch over 10 feet, or an underlayment that traps rather than manages moisture will all work against a tight installation regardless of how well the planks acclimated. A pre-installation checklist should include a moisture meter reading, a straightedge check for flatness, and confirmation that the chosen underlayment matches the subfloor type.
Installation Method Errors: Floating vs. Fixed Attachment
LVP is engineered as a floating floor, meaning the planks interlock with each other but are not fastened to the subfloor. This freedom to move is what lets the material expand and contract without buckling. When planks get anchored at the perimeter, pinned under cabinetry, or trapped by baseboards installed with zero clearance, the floor has nowhere to release built-up expansion pressure, and it will find relief somewhere else, usually as a gap at the weakest seam.
How Temperature Extremes Trigger Expansion and Contraction
Vinyl expands and contracts more dramatically with temperature swings than laminate or engineered wood, which is part of why sun exposure and unconditioned rooms cause outsized gap problems. Direct sunlight through a south-facing window can raise a plank's surface temperature 20 to 30 degrees above the room's ambient reading, expanding that section of floor. When the sun moves and the surface cools, the plank contracts back, and repeated cycles like this loosen the lock joint over time. Cold rooms work the opposite direction, with sustained low temperatures keeping planks in a contracted state that opens gaps at the seams.
Mitigation options include reflective or UV-filtering window treatments in high-sun rooms, planning for radiant or supplemental heat in basements and additions, and selecting an underlayment with better thermal stability for rooms prone to temperature extremes. Filling or caulking the gap is not a solution here since vinyl needs room to keep moving.
Essential Equipment and Materials for Diagnosing LVP Gaps
Measurement and Diagnostic Tools
A tape measure or feeler gauge confirms whether a gap falls inside the 1/16 inch acceptable range or crosses into the 1/8 inch concern threshold. A hygrometer tracks room humidity over several days rather than a single snapshot, and a pin-type or pinless moisture meter checks the subfloor if you suspect moisture is driving the movement.
Repair Tools for Mechanical Closure
A suction cup gap-closing tool is the standard approach for re-engaging a partially disengaged click-lock, working by gripping the plank surface and pulling it back into alignment with its neighbor. This works well on end gaps where the lock has only slipped slightly, and works less reliably on side gaps where the joint has fully separated.
Other Materials You Will Need
- Hygrometer and moisture meter for environmental diagnosis
- Suction cup plank-pulling tool for mechanical closure
- Replacement transition strips if wall clearance needs adjustment
- Underlayment samples if you're reassessing subfloor prep
If the diagnostic step points to a subfloor moisture problem or a widespread acclimation failure, that's usually the point where a laminate floor installation and repair specialist can save you from guessing at a fix that only addresses the surface symptom.
Gap Classification: Where They Appear and What It Tells You
Where a gap shows up on the plank tells you a lot about what caused it and how easily it can be closed.
End Gaps (Short Edge)
Gaps at the short end of a plank, within the same row, are usually the easiest to close because the click-lock mechanism only needs to be re-engaged, not rebuilt. A suction cup tool applied evenly across the plank face typically pulls the joint back together.
Side Gaps (Long Edge)
Gaps along the long side, between rows, indicate the click-lock has partially or fully disengaged. Small side gaps sometimes respond to the same mechanical closure method, but a fully separated lock joint along a long run usually will not hold once you release pressure, since the interlocking teeth have already pulled apart.
Wall Gaps
Expansion gaps at the perimeter are intentional and necessary, and baseboard or trim typically hides them from view. A wall gap only becomes a problem if it's inconsistent, wider on one side of the room than the other, which points to a squaring or layout issue during installation rather than normal expansion.
Mechanical Solutions vs. Full Diagnosis and Repair
Closing a gap mechanically treats the symptom, not the cause, so it's worth understanding when a quick fix is appropriate and when it's a stopgap that buys time before a real fix.
When Mechanical Closure Is the Right Call
- The gap is a small end gap under 1/8 inch
- The lock mechanism is still partially engaged
- No cupping, buckling, or moisture signs are present nearby
- The room has not had a major humidity or temperature event recently
When Full Diagnosis Makes More Sense
- The gap is a wide side gap with a fully disengaged lock
- Gaps recur in the same spot after closure
- Multiple gaps cluster in one area of the room
- The room sits over a known moisture-prone area like a bathroom or basement
Never fill, caulk, or glue an LVP gap. Unlike laminate or wood, vinyl's expansion and contraction range is large enough that rigid filler will crack within a season, and trapped filler can hold moisture against the plank edge.
Prevention Strategy: How to Install and Maintain LVP to Avoid Gaps
Preventing gaps starts before the flooring ever arrives on site. A pre-purchase humidity assessment and baseline room reading tell you what conditions the material will actually live in. Full acclimation for 48 to 72 hours in the installation room, correct subfloor moisture testing and leveling, and appropriate underlayment selection address the installation-stage risks. A floating installation with proper 1/4 inch wall spacing and staggered plank layout keeps the lock joints engaged as designed.
Room-by-Room Risk Assessment
- South-facing rooms with large windows: add UV-filtering window treatments
- Basements and unheated additions: stabilize temperature before installation
- Kitchens and bathrooms: verify moisture barrier and subfloor moisture readings
- Rooms with in-floor heating: confirm the LVP product is rated for radiant heat
Ongoing humidity control through your HVAC system, keeping direct sunlight off high-risk floors, and periodic visual checks at seams are the maintenance habits that keep a properly installed floor from developing gaps in the first place.
Special Considerations for Challenging Installations
Open-concept floor plans that stretch a single continuous run of LVP across a large square footage need expansion joints or transition strips at defined intervals, since floating floors have a maximum recommended run length before built-up expansion pressure becomes a problem. Homes with radiant floor heating require an LVP product specifically rated for that heat source, since standard products can soften or expand unpredictably under sustained warmth.
If your project involves any of these conditions, a floor installation and repair professional can evaluate the subfloor and layout before a single plank goes down, which is considerably less costly than reworking a floor after gaps appear.
Maintenance and Long-Term Care
How do you prevent LVP gaps from coming back after a repair? Keeping indoor relative humidity between 30 and 50 percent year-round, limiting direct sun exposure on the floor, and avoiding anchoring or pinning planks during furniture placement all reduce the chance that a closed gap reopens once seasonal conditions shift again.
- Run a hygrometer in problem rooms through at least one full heating and cooling season
- Inspect seams near windows and exterior walls twice a year
- Keep felt pads under furniture legs rather than letting them dig into plank edges
- Address any subfloor moisture source promptly, since it will outlast any surface repair
Things to Consider Before You Start
- Do you know your gap width? A gap under 1/16 inch at the wall is normal; anything approaching 1/8 inch or wider deserves a closer look.
- Have you ruled out subfloor moisture? A gap that keeps returning after mechanical closure often has a moisture source feeding it.
- Is the gap isolated or spreading? One end gap in a corner is different from multiple gaps across a room.
- Do you have the diagnostic tools? A hygrometer and moisture meter tell you more in ten minutes than weeks of guessing.
Where you land on these questions determines whether this is a weekend DIY fix or a job worth handing to a professional.
Why Homeowners Bring in Ace Handyman Services
- Peace of mind when a costly flooring investment is on the line and a misdiagnosis could mean redoing the whole room
- A one-year labor warranty backing any repair or installation work performed
- No need to source, learn, or return a moisture meter, suction cup tool, or leveling equipment
- Background-checked, multi-skilled W-2 craftsmen, not gig workers pieced together for a single job
- A predictable weekday timeline that doesn't eat into your weekend
- Honest scoping that recommends mechanical closure when that's genuinely enough, rather than upselling a full tear-out
- Cleanup included, so you're not left sweeping up plank dust and packaging after the work is done
If your LVP gaps keep coming back, or you'd rather have a professional confirm the cause before you invest more time in a DIY fix, reach out to your local Ace Handyman Services office to get an assessment scheduled.
When a repair turns out to be bigger than a weekend, request an estimate from Ace Handyman Services and a local, background-checked craftsman will handle it from there.
Frequently Asked Questions
How do I fill gaps between LVP planks?
You generally should not fill LVP gaps with caulk or filler. Instead, use a suction cup tool to mechanically re-engage the click-lock joint for small end gaps, and address the underlying humidity, acclimation, or installation issue so the gap doesn't return.
How do I fix a gap between floor planks?
Identify whether it's an end gap or side gap, then use a suction cup tool to pull the plank back into its locking position. If the lock is fully disengaged or the gap keeps reopening, the fix needs to address the environmental or installation cause rather than just the visible symptom.
Why is my vinyl plank flooring separating?
Separation usually traces back to insufficient acclimation before installation, humidity swings that repeatedly expand and contract the material, or an installation error like inadequate wall spacing that leaves the floor no room to move without stressing the seams.
What humidity level causes LVP gaps?
Relative humidity below 30 percent or above 50 percent puts stress on vinyl plank flooring, causing contraction in dry conditions and expansion in humid ones. A hygrometer lets you confirm your room's actual reading rather than guessing.
How long should LVP acclimate before installation?
Most manufacturers recommend 48 to 72 hours of acclimation, with planks left unopened in the room where they'll be installed so the material reaches the same temperature and humidity as the space before installation begins.
Can I prevent LVP gaps in a room with large south-facing windows?
Yes. UV-filtering or reflective window treatments reduce surface heating on the floor, and selecting an underlayment with better thermal stability helps limit the expansion and contraction cycle that direct sun exposure causes.