Best Underlay for LVT 2026: Glue-Down, SPC Click and Herringbone Underlay Picks

Choosing the right underlay for LVT is the single biggest determinant of how the finished floor feels, sounds, and lasts. Get it right and the floor performs as the manufacturer specs. Get it wrong and you'll have rocking joints, hollow acoustics, premature wear, or worst case the wrong format underlay voiding your warranty. This guide covers the right underlay choice for each LVT format with the actual product picks from our range.

Quick answer: best underlay by LVT format

  • For glue-down LVT (Style LVT, Karndean Knight Tile, Polyflor Camaro): NO underlay. Glue-down LVT bonds directly to the subfloor. Adding underlay defeats the install and voids the warranty.
  • For SPC click (Woods Click SPC, Karndean Van Gogh Rigid Core): 1.5-2mm IXPE foam underlay OR use the attached underlay if pre-bonded to the plank. Don't use thick foam.
  • For LVT click (non-SPC click LVT): 1.5-2mm IXPE foam OR thin fibreboard underlay with vapour barrier.
  • For herringbone LVT: depends on format. Glue-down herringbone = no underlay. SPC herringbone = 1.5mm IXPE attached or thin foam.
  • For laminate (not LVT but commonly confused): 3-5mm PU or rubber underlay. Different product entirely.

Related guides

Why glue-down LVT doesn't need underlay

Glue-down LVT (Style LVT, Karndean Knight Tile, Polyflor Camaro, Karndean Van Gogh standard) is bonded directly to the subfloor with adhesive. The adhesive bond IS the floor's stability and acoustic dampening. Adding an underlay between the LVT and the subfloor breaks that bond, allows the planks to rock, and voids the manufacturer warranty.

What glue-down LVT actually needs:

  • Subfloor flatness (max 3mm under 2m straight edge)
  • Subfloor dryness (RH below 75%)
  • The correct adhesive (F-Ball Styccobond F44 for most installs, F46 for damp subfloors, F49 for underfloor heating)
  • Self-levelling compound if subfloor unevenness exceeds the spec

NOT what glue-down LVT needs:

  • Foam underlay
  • Fibreboard underlay
  • Rubber underlay
  • Anything else between LVT and subfloor

If a fitter or retailer recommends adding underlay under glue-down LVT, they're either inexperienced or misinformed.

Why SPC click LVT needs (some) underlay

SPC click floats over the subfloor on its underlay. The underlay's job is sound dampening, slight cushioning, and bridging minor subfloor imperfections. SPC click doesn't bond to the subfloor.

Two options for SPC click underlay:

Option A: Use the attached pre-bonded underlay

Most quality SPC click planks come with a pre-attached IXPE foam underlay bonded to the back. Karndean Van Gogh Rigid Core, our Woods Click SPC, Polyflor Camaro Rigid Core all have this. With pre-attached underlay you DO NOT add a separate underlay; the attached one is the spec.

Adding another underlay under pre-attached makes the floor too soft, causes joint failure, and voids warranty.

Option B: Use a thin separate IXPE foam if no attached underlay

If the SPC click planks don't have attached underlay, use 1.5-2mm IXPE foam (e.g. Xtrafloor Flex Pro) with vapour barrier. Don't go thicker. Thick underlay (5mm+) causes the click joints to rock and fail.

What about Quickstep / Sonic-Gold / Timbermate type underlays?

These are made for laminate flooring, not LVT or SPC click. They're 3-5mm fibreboard or premium foam designed for laminate's specific acoustic needs. Using them under SPC click makes the floor too soft and rocks the joints.

For laminate, these underlays are correct. For LVT or SPC, don't use them.

Underlay for herringbone LVT

  • Glue-down herringbone (Style Parquet, Karndean Knight Tile Parquet, Van Gogh Parquet): NO underlay. Glue-down to subfloor.
  • SPC herringbone click (Karndean Van Gogh Rigid Core Parquet, Polyflor Camaro Rigid Core herringbone): use the attached underlay OR 1.5-2mm IXPE foam if no attached.

Herringbone is more sensitive to underlay quality than straight-lay because the 90-degree joints multiply any rocking. Cheap or wrong-spec underlay shows up faster in herringbone.

What about vapour barriers?

For SPC click on concrete or screed subfloors, a vapour barrier (typically 0.2mm polyethylene sheet) goes under the underlay to block residual moisture. Many premium IXPE underlays have a vapour barrier already bonded to one side.

For SPC click on a properly screw-fixed timber subfloor in a heated room, vapour barrier isn't required.

Underlay for kitchen / bathroom LVT

Wet-zone underlay specifications:

  • Glue-down LVT in kitchens / bathrooms: no underlay, use F46 damp-tolerant adhesive.
  • SPC click in kitchens / bathrooms: attached IXPE underlay (waterproof), seal the perimeter with silicone, ensure the click joints are properly seated.

See our Best LVT for Kitchen guide for kitchen-specific recommendations.

Underlay for underfloor heating

  • Glue-down LVT over UFH: no underlay, use F49 UFH-rated adhesive.
  • SPC click over UFH: thin IXPE foam (1.5mm) OR attached underlay. Avoid thick foam or fibreboard because they insulate the heating and reduce efficiency.

UFH surface temperature ceiling: 27°C across all LVT formats. Verify per product spec.

Brands and product picks at FW

Xtrafloor Flex Pro Underlay

Our go-to SPC click underlay if the planks don't have attached underlay. 1.5mm IXPE foam with vapour barrier. Suitable for residential SPC click installs over concrete, screed, or properly fixed timber subfloors. Browse Xtrafloor Flex Pro.

F-Ball Styccobond F44 LVT Adhesive (for glue-down)

Industry-standard LVT adhesive. Used for Karndean, Polyflor Camaro, our Style LVT, Impression and Grande ranges. Spread with notched trowel, 15-30 minute open time.

F-Ball Styccobond F46 (damp-tolerant)

For glue-down LVT over subfloors with marginal damp or moisture concerns. Higher cost than F44 but the right pick for ground-floor kitchens, basements, and properties with limited DPM.

F-Ball Styccobond F49 (UFH)

Specifically for glue-down LVT over underfloor heating. Heat-tolerant adhesive that maintains bond at sustained 27°C surface temperature.

F-Ball Stopgap 800 / 1200 (self-levelling compound)

For subfloors that need levelling before glue-down LVT install. Allow full cure time before applying adhesive.

Common underlay mistakes

  • Adding foam underlay under glue-down LVT (voids warranty, causes rocking).
  • Using laminate underlay (3-5mm fibreboard) under SPC click (too thick, joint failure).
  • Skipping the vapour barrier on concrete or screed subfloors (moisture damages SPC over years).
  • Using wrong adhesive for the install conditions (F44 in damp room voids warranty; F46 on UFH degrades; F49 is required for UFH).
  • Stacking attached underlay PLUS separate underlay under SPC click (too soft, joints rock).

Frequently asked questions

Do I need underlay under Karndean LVT?

Standard Karndean (Knight Tile, Van Gogh glue-down, Da Vinci, Art Select) glue-down LVT does NOT need underlay. Karndean Van Gogh Rigid Core SPC click has attached underlay built-in; no separate underlay needed.

Do I need underlay under Polyflor Camaro?

Standard Polyflor Camaro glue-down does NOT need underlay. Polyflor Camaro Rigid Core has attached underlay; no separate underlay needed.

Do I need underlay under herringbone LVT?

Glue-down herringbone: no underlay. SPC click herringbone: use attached underlay or 1.5-2mm IXPE foam.

Can I use carpet underlay under LVT?

No. Carpet underlay is too soft and too thick for any LVT format. It causes joint failure and voids warranties.

What's the cheapest decent SPC click underlay?

Xtrafloor Flex Pro is our value pick at trade-direct pricing. 1.5mm IXPE with vapour barrier. Suitable for all SPC click installs over concrete or screed.

How much underlay do I need?

Calculate room area, add 5% for waste. Most SPC click underlay comes in 6.5m² rolls.

What to do next

Browse our underlay range or our LVT adhesive range. For full subfloor prep needs see our floor screed range. Free UK delivery over £200, local pickup from our Worthing warehouse.