Will mold grow underneath vinyl plank flooring?

Why Mold Grows Under Vinyl Planks？

Wet Subfloors:

Concrete: Sweats moisture for years.

Wood: Soaks up humidity or leaks.

Result: Trapped dampness without a moisture blocker.

Installation Mistakes:

No plastic layer under concrete.

Gaps left unsealed (lets water sneak under).

Putting planks over old water damage.

Water Invaders:

Leaky pipes, floods, or spills seeping through cracks.

Muggy basements/humid air causing "sweating" under planks.

Stop Mold Before It Starts:

Check Subfloor Dryness:

Use a moisture meter (<4% for wood, <3.5 lbs/24h for concrete).

Add a Moisture Block:

Concrete: Lay thick plastic (6–8 mil) or special padding.

Wood: Use breathable underlayment.

Let Planks Adjust:

Leave boxes in room 48 hours before installing.

Seal EVERY Gap:

Caulk edges, pipes, and doorways with silicone.

Control Air Moisture:

Keep indoor humidity under 50% (dehumidifiers help!).

Key Takeaways:

Vinyl planks don’t mold, but wet subfloors + bad installs DO.

Block moisture, seal gaps, control humidity → near zero risk.