ᐅ Should a vapor retarder film be glued under laminate flooring?

Hello,

I want to install laminate flooring over the screed (with underfloor heating) in my basement. I noticed on the laminate packaging that for a "mineral substrate," a vapor barrier (I assume a 0.2mm PE foil) should be laid underneath.

a) Does the foil need to be sealed airtight at the seams with tape (similar to a vapor barrier/vapor retarder in a roof)?

b) Should the foil also be extended up the walls beneath the baseboards and possibly taped there as well (like on a roof)?

Thank you very much for your answers.

The membrane must be installed with sufficient overlap (about 20cm (8 inches)) and turned up at the edges. Sealing with adhesive tape is necessary; otherwise, the entire assembly would not be truly vapor-tight. You should choose the appropriate tape for this purpose, not just any tape that happens to be on hand. For more specific advice (which membrane, which tape, and which underlay for your purpose are suitable), consult a specialist retailer. I am also an amateur planning to install engineered hardwood flooring myself soon. There are also combination products for vapor barriers and sound insulation, but these must also be sealed at the joints.

The suitability of a floor covering for use with underfloor heating primarily depends on the material’s thickness and its thermal conductivity. These two factors determine the thermal resistance value (R-value) — the lower this value, the better the compatibility with underfloor heating. The thermal resistance must not exceed 0.15 m²K/W. Laminate flooring with a thickness of 9 millimeters (0.35 inches) has a thermal resistance of approximately 0.044 m²K/W. The laminate must be explicitly specified and approved by the manufacturer for installation over underfloor heating, including an indication of its R-value. If impact sound insulation foils are installed underneath, their R-values must be added.

What is the purpose of the vapor barrier? Is it intended to prevent moisture from below penetrating the laminate, or to stop moisture in the room air from diffusing by vapor pressure into the floor structure? The floor construction down to the structural slab/floor plate, as well as the connection to rising masonry or walls including waterproofing and insulation, should be known before deciding on such a detail.

I would like to get started here.

We plan to install click laminate flooring in the attic hallway and bedroom. It is said that on mineral substrates and/or underfloor heating systems with warm water, a vapor barrier must be installed.

Nowadays, there are countless 2-in-1 products combining impact sound insulation and vapor barriers, but we would prefer to avoid the aluminum layer.
However, I’m not keen on first laying a PE foil and then placing regular underlay on top of that.

Are there 2-in-1 products available without an aluminum layer?
Thanks in advance.

Just take a look at the websites of various manufacturers (Logoklic, Parador...) because you could write entire novels about this.

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