That vapor barrier would go between the subfloor and the underlayment. “Combination underlayments,” as described on learn.
Location: Floor underlayment is positioned between the subfloor and finished flooring, whereas floor vapor barriers are typically installed beneath the underlayment or directly on top of the subfloor, depending on the specific requirements of the flooring system.
Yes, a moisture barrier is recommended on a wood subfloor to prevent moisture from seeping into the flooring material, which can cause warping, mold, or mildew. It is especially crucial in areas prone to high humidity, such as basements or bathrooms.
You have the top layer that is your floor covering (Hardwood, Laminate, Vinyl, Carpet, etc.), next you have the underlayment (usually a thin layer of fiber, foam, rubber), below that you have your subfloor (plywood, OSB, concrete), and lastly you have the joists which are the foundation to your floors.
What You Need For Your Flooring Application. We recommend for you to read the flooring installation instructions for proper installation. 95% of the time, they will recommend a 6-mil vapor barrier to be installed underneath the flooring.
Underlay protects your laminate against moisture damage
Cold ground floor subfloors are often prone to damp, which can damage your laminate. An underlay with a vapour barrier helps prevent this.
Both are designed to keep moisture out of your home and can be made from various materials. But there are a few key differences, the most apparent being that moisture barriers are better at keeping out liquids, and vapor barriers are better at keeping out water in its gaseous state.
Not all underlayments are moisture barriers. Some underlayments require an additional layer or film to form a moisture barrier. FloorMuffler® offers several underlayments with built-in moisture protection that can be used in a variety of hard surface flooring applications.
It is rolled out between the actual laminate flooring planks and the subfloor. Very often, particularly in a below-grade installation on a concrete basement floor, a vapor barrier is recommended in addition to the underlayment. That vapor barrier would go between the subfloor and the underlayment.
Because a vapor barrier is a low permeable barrier, it keeps moisture from passing through. This is beneficial to keep moisture away from a dry surface but will trap moisture behind it if installed on a water-damaged concrete wall, causing the wall to fail further.
Use moisture barriers or underlayment specifically designed for LVP flooring to prevent moisture from seeping up from the subfloor. Proper sealing around the edges and at the joints can also prevent water from penetrating beneath the planks.
Wall installation for vapour control layers
Generally speaking when you install a VCL to the walls of existing properties, you are installing a stud wall with insulation. If you use permeable insulation material such as sheep's wool, rockwool or fibreglass, the VCL is installed to the warm side of the insulation.
Vapor barriers are installed along, in, or around walls, ceilings, and floors. Of course this is done to prevent moisture from spreading and potentially causing water damage.
Subfloor Material
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).
This kind of underlayment is commonly called tar or felt paper and can either be made with natural materials, such as wood cellulose, or synthetic materials, like polyester or fiberglass. The base materials are then soaked in a protective coating made of bitumen (asphalt) or something similar.
Separate Underlayment. Laminate flooring manufacturers typically recommend an underlayment. What happens if you don't put padding under laminate flooring is moisture coming through the subfloor can cause it to warp and mildew. And footsteps on the floor will be louder.
From a moisture-protection standpoint, it is my strong belief – reinforced by decades of ACI study and expert opinions – that the under-slab vapor barrier should be located directly below the slab, without the use of a layer of granular fill (sometimes sand) sandwiched between the slab and vapor barrier, often referred ...
Vapor barrier underlayment, also known as moisture barrier underlayment, is designed to prevent moisture from seeping into your floors. In regions where humidity levels fluctuate, or in installations over concrete subfloors, the risk of moisture damage is significant.
Subfloor. The subfloor is the foundation beneath your finish flooring materials. Providing a continuous structural surface over the floor joist. Subfloors can consist of wood plank, plywood, OSB (Oriented Strandboard) and concrete.
The Cons of Vapor Barrier Installation
Although vapor barriers aim to prevent moisture from entering the structure, they can also trap moisture inside. If not properly installed or upheld, this could result in the proliferation of mold and other issues related to moisture.
Vapor barriers and laminate flooring underlayment
If your installation is over concrete, we recommend a 6-mil-poly vapor barrier – even if the underlayment you are installing already has a vapor barrier attached.
Vapor Barrier: A material that prevents moisture from passing through. This is especially important in areas where moisture can seep up from the subfloor, like basements or ground-level installations. Underlayment: A layer of material placed between the subfloor and the hardwood.