Laminate underlay: how to choose the right one
What an underlay does under laminate, the types available, when you need a moisture barrier and what to use on underfloor heating.
The underlay is the cheapest part of a laminate floor and one of the most important. It decides how the floor sounds, how it feels and how long the click joints last.
What an underlay does
- Levels small irregularities in the subfloor so the joints are not stressed
- Reduces footstep noise, both in the room itself and in the room below
- Protects against moisture from concrete or screed, if it has a vapour barrier
- Adds a little insulation and comfort underfoot
Two kinds of sound
Underlays are tested for two different noises:
- Walking sound (reflected sound): the hollow clicking you hear in the same room. A good underlay makes laminate sound more like real wood.
- Impact sound: the noise that travels to the room below. In apartments this is often regulated, so check the building's rules.
Common types
| Type | Good for |
|---|---|
| Foam (PE) | Budget option on flat, dry subfloors |
| Fibreboard / wood fibre | Bridging unevenness, natural feel |
| Mineral-filled or XPS boards | Good levelling and sound reduction, common for click floors |
| Acoustic underlay with heavy layer | Apartments and upstairs rooms |
| Underlay with integrated vapour barrier | Concrete and screed floors |
Do you need a moisture barrier?
On mineral subfloors (concrete, sand-cement screed, anhydrite) the answer is yes. New screed in particular keeps releasing moisture for months. Use an underlay with an integrated vapour barrier, or lay a separate PE foil of at least 0.2 mm with overlaps of about 20 cm, taped at the seams and turned up at the walls.
On wooden subfloors you do not add a vapour barrier, as the wood needs to breathe.
Underfloor heating
Laminate can go on most water-based underfloor heating systems, but the floor and underlay together must let the heat through. Manufacturers usually set a maximum total thermal resistance of around 0.15 m²K/W for floor plus underlay, and a maximum surface temperature of about 27 °C. Choose a thin, dense underlay that is approved for underfloor heating and check the figures on both data sheets.
Practical tips
- Lay the underlay at right angles to the direction of the laminate
- Butt the seams together, do not overlap them, unless the manufacturer says otherwise
- Never put two underlays on top of each other; the floor becomes too soft and the joints can break
- Some laminate has an underlay already attached. In that case, add only a vapour barrier where needed
Order the underlay together with the floor, so you are sure the two are compatible. EasyFloors stocks underlays for every subfloor.
Underlays & finishing
Underlays for every subfloor, plus skirting, profiles and tools.