Begin installation by laying a plastic vapour barrier (minimum 6 mm thick) or any other manufacturer-recommended barrier on the concrete subfloor to prevent moisture from reaching the laminate flooring. Use vinyl tape to secure the barrier and keep it from coming out.
Laminate flooring can be installed over basically any flat and level surface, including wood subfloors, hardwoods, tile, concrete and more. It is not recommended to install laminate flooring over a soft surface, like carpet, because it doesn't provide enough support for the flooring.
Therefore, because concrete is porous, it's a good idea to install a vapor barrier over your concrete subfloor before installing your flooring. This way you can stop the vapor drive of water upward to your floors, protecting them from any damage (source).
It is very advisable to install a vapour barrier between concrete and foam underlayment. That way the moisture of concrete won`t damage laminate flooring. Vapour barrier is also another temperature barrier which keeps cold air from concrete to influence laminate flooring.
If you're installing laminate flooring over a subfloor, like concrete, you may want to install an underlay with a vapor barrier for added protection against moisture. Make sure you choose an underlay that works with an attached pad. Our top choice is Sentinel Protect Plus Underlayment.
With a concrete subfloor, you will need an underlayment that acts as a vapor barrier in order to prevent moisture from penetrating through to your laminate installation. The normal choice is a thin foam pad material made of polyethylene or polypropylene, which rolls out in sheets.
Install a plastic vapor barrier: If your concrete passes the moisture test, then plastic sheeting at least 6 mils thick will prevent moisture from getting into your laminate flooring. Where plastic sheets must be joined, overlap the sheets by several inches, and use strong vinyl tape to secure them.
Lay the Underlay
Simply put, underlay is a thin layer of foam that goes in between your flooring and your subfloor. It helps add insulation to your room and makes the installation process easier.
If you are installing your vinyl plank flooring over a concrete subfloor, you may want to use an underlayment for three reasons. First, it will give you some added cushion to help make the floor softer to walk on. Second, you may want an extra vapor barrier above the subfloor to reduce any risk of moisture.
Vapour barriers are materials used for damp proofing. The best approach is to lay a sheet (also called a membrane) of PE plastic 0.2mm thick beneath laminate flooring. Sheets are available in different sizes. A single sheet measuring four by four metres is large enough to cover most rooms.
The American Concrete Institute (ACI) also recommends a minimum of 10 mil polyethylene or thicker for vapor retarders under concrete. According to its Guide to Concrete Floor and Slab Construction ACI 302.1R-15, thicker poly provides a better barrier and is also more puncture resistant.
Without underlayment to add a layer between these damp subfloors and the surface flooring, your laminate can quickly become wet, warped, and mildewy, harming its overall integrity. Moisture over time can also break down floor adhesive which causes the floor to start warping.
“Without a vapor barrier, concrete will deteriorate much faster through water vapor intrusion which degrades the quality of the concrete over time and can lead to foundation and building failures, like Surfside Condominium Collapse in Miami, Florida,” says vapor barrier plastic sheeting expert and Americover account ...
The best materials for floor underlayments include foam, cork, and polyethylene (thermoplastic). If you're looking to add softness while absorbing sound and preventing mold and mildew, cork might be your best bet. 4 If your main goal is to add a moisture barrier, polyethylene might be a better choice.
An even surface for laminate flooring is essential. Any bumps or dipping with laminate flooring will cause the flooring to squeak or fall apart. To prevent this, fill low spots with a patch or self-leveling concrete. Any gaps larger than a quarter-inch wide, gouges, and large chips should be filled with a patch.
Don't install your laminate on any floor with a drain. Don't install laminate on any uneven subfloor or outdoors. Don't install your laminate over residential carpet. Don't install a second layer of laminate underlayment.
Felt and cork are the two best underlayment materials for providing sound insulation.
Moisture Shield
Furthermore, if you are installing vinyl planks directly over a concrete floor, a waterproof underlayment is essential.
The slab needs to be free of debris, as dry as possible and level. The LVP needs to be thick enough so imperfections don't telegraph through, and then you'll be fine. You'll also need to consider if you have moisture concerns; if so, a moisture-barrier will be recommended.
The application of vapor barrier in exterior concrete is unnecessary due to the fact that water penetration does not matter. Any slab on grade that is enclosed and on the interior of a building should have a vapor barrier installed prior to pouring concrete, especially if flooring will be applied.
You don't need to seal a concrete floor before installing laminate; however, to prevent moisture from the concrete floor from affecting your laminate, install a vapor barrier of polyethylene film. Install this barrier even if the concrete subfloor is covered by vinyl, linoleum, terrazzo or ceramic tile.
Vapor barriers are a way to keep moisture from getting into the concrete. Note: A vapor barrier is not the same as an underlayment. However, some underlayments act as vapor barriers.