Do I need a moisture barrier under basement LVP flooring?
Installing luxury vinyl plank flooring directly on concrete without a vapor barrier traps moisture underneath, requiring you to lift the material and decide whether to run the barrier up the walls and seal the perimeter. Without this protection, moisture will continue to damage the floor and trim.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 31.7× more often in r/Flooring than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1pulling up the flooring to dry it and install a vapor barrier manuallyDid this help you?
- 2relying on the wax seal to handle sealing between the toilet and flangeDid this help you?
- 3waterproofing only the top side of the cement board that will be tiled overDid this help you?
- 4Looking around online for confirmation on correct installation methodsDid this help you?
- 5laying plastic directly on the ground without anything underneathDid this help you?
- 6using large rolls of 6 mil plastic sheetingDid this help you?
- 7Using traditional foam without a moisture linerDid this help you?
- 8Opting for alternative flooring options if budget allowsDid this help you?
- 9Doing it yourself as a DIY project by laying 10 mil plastic on the dirt to reduce moistureDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“One thing I can't seem to get a definitive answer on is whether the walls should be taped with paper tape to make sure no vapor comes up to the floors.”source ↗
“before I go too much further wanted to make sure I'm not doing anything I would regret.”source ↗
“I guess my concern is would any moisture that could come up from underneath start to breed mold?”source ↗
“Are either/both of these options a good idea for a basement, or does that barrier then trap moisture underneath as the slab breathes that can't evaporate through the carpet?”source ↗
“Does trapping water underneath just hide a problem that would be better to discover with a wet carpet spot?”source ↗
“I am seeing effervescent crystals on the dirt under the house. I have white oak plank flooring sitting directly on the frame. This phenomena has been present for a couple of years. My thinking is water table maybe getting a little higher. Has anyone used any local company to do this?”source ↗
Where this came up
People with this problem also raised
- 2Do I need a waterproof membrane under tile or a toilet flange?
- 4Can you use fiberglass insulation in a basement after flooding?
- 5Painted concrete basement floor keeps dusting and crumbling
- 2Temporary ways to cover exposed basement insulation
- 3Can I insulate and finish basement walls if they get damp?
- 4Do I need underlayment for luxury vinyl plank flooring?