Quick Answer
If your luxury vinyl plank does not have attached pad, use a 1 mm to 1.5 mm vinyl-specific foam underlayment with an integrated 6 mil vapour barrier on slab installations. Popular options: MP Global QuietWalk LV, Floorlot Blue, Roberts First Step, and Bestlaminate Pro-Vapor 3-in-1.
Never use thick (3 mm+) laminate underlayment under LVP. The plank flexes, the click joints work themselves loose, and the warranty is void.
When You Need Underlayment
- No attached pad on your plank. Many entry-level LVP and most loose-lay sheet vinyl ship without it.
- Slab subfloor. Concrete always needs a vapour barrier, even if your plank has attached pad.
- Upper floors where sound matters. An acoustic underlayment can reduce impact noise to neighbours below.
When You Should Not Add Underlayment
- Your plank already has attached IXPE or cork pad and you are on a wood subfloor.
- You are gluing down LVT (it bonds directly to a primed substrate).
- The product warranty explicitly forbids additional underlayment.
Vapour Barrier vs Sound Pad vs Combo
On a slab, the non-negotiable spec is a 6 mil polyethylene vapour barrier. Most "3-in-1" vinyl underlayments combine the vapour barrier, a thin foam cushion (about 1 mm), and a small acoustic rating into a single rolled product. That is what you want for most residential slab installs.
Brand Cheat Sheet
- Best all-rounder: MP Global QuietWalk LV (1.6 mm, 6 mil vapour barrier).
- Budget: Roberts First Step (2 mm, with vapour barrier).
- Best acoustic: AcoustiCork U18 or QuietWalk Plus.
- Slab moisture trouble: Floorlot Blue with 8 mil vapour film.
Real-World Notes
Field experience matters more than spec sheets here. Installers who do this work week-in week-out will tell you the same things: the substrate is everything, the acclimation step is non-optional, and a single missed prep detail will show up six months later when the seasons change.
Climate also plays a bigger role than most homeowners expect. A floor that performs perfectly in coastal Florida might cup in dry Denver winters. Match the product to the climate zone, and your warranty terms to your actual indoor humidity range.
Insurance and resale considerations are worth a mention too. Document the install with photos, keep the receipts, and save the lot numbers. Future buyers ask, and future repairs need them. The best underlayment for vinyl plank flooring is a long-term decision, treat it like one.
One last note from the trade: cheap is rarely cheap. The lowest-priced product on the shelf usually has the thinnest wear layer, the loosest click, and the worst warranty terms. A mid-priced product from a known brand will outlast the budget option by 50 percent or more on average, which works out cheaper per year of service.
Frequently Asked Questions
Does the answer change for rental properties?
The general guidance holds, but landlords usually optimise for durability over aesthetics, so they lean to the cheapest waterproof option that will survive turnover after turnover.
What about radiant heat?
Always confirm your flooring choice is rated for radiant heat (most rigid-core LVP is, solid hardwood usually is not). Manufacturers publish a maximum subfloor temperature, typically 82°F (28°C).
How long should I let the materials sit before installing?
48 hours in the room of installation is the safe default for laminate and LVP. Engineered hardwood needs longer, often 7 to 14 days, until its moisture content is within 2 to 4 percent of the subfloor.
Does the same answer apply in the UK?
Mostly yes. UK retailers like B&Q, Wickes and Carpetright sell the same product categories with similar specs, though pricing and brand names differ.
Pro Tips From the Trade
- Buy 10 percent extra. You will cut waste at every wall and inside every doorway. Pros budget 10 percent overage on rectangular rooms and 15 percent on rooms with diagonals or lots of cutouts.
- Keep a few planks aside. Future repairs need a colour and lot match. Stash at least one full carton in the garage or basement, ideally from the same production run.
- Photograph the install. Snap pictures of the subfloor, vapour barrier, expansion gaps, and any transitions before the baseboards go on. Warranty claims often hinge on documentation.
- Save the receipts and lot numbers. Almost every flooring warranty requires proof of purchase and the production lot to be honoured.
If you take just one thing from this guide, take this: prep work decides 80 percent of the outcome. Spending an extra hour on subfloor inspection, moisture testing, acclimation, and laying out a dry run pays back ten times over the life of the floor. Skipping prep to save an afternoon almost always costs a weekend later.
And when in doubt, call a flooring contractor for an hour-long paid consult. A pro walking your room will spot issues you might miss, and the fee is trivial compared to a botched install.
Bottom Line
Flooring decisions sit at the intersection of budget, lifestyle and resale value. Get the prep right (flat, dry, clean subfloor; correct underlayment; proper acclimation) and even a mid-priced product will look and perform like a premium one. Cut corners on prep and even the most expensive plank will telegraph every flaw underneath.
