How to Lay a Moisture Barrier under Laminate Flooring

Lead Image
  • 2-4 hours
  • Beginner
  • $45
What You'll Need
Moisture barrier
Closed-cell foam
4 mil poly or plastic
Foam padding
Measuring tape
Packing tape

There are different kinds of moisture barrier available in the market. All of which are satisfactory once applied and sealed appropriately, you too can easily do it on your own. Make sure that you select well the moisture barrier that suits your laminate flooring. Meanwhile, laminate flooring manufacturers have moisture barriers particularly designed to be used with their own products. The main objective of the moisture barrier paint is to hold moisture from reaching the material of the laminate flooring coming from the subfloor below. For instance on concrete subfloors, the moisture barrier installation is particularly important since concrete can grasp moisture and humidity for an extended time compared to other subflooring material. Laying a moisture barrier under laminate flooring eliminates the risk of moisture problems on account of moisture seeping into the main structure from underneath the laminate flooring.

Prepare the Area

Consider the subfloor which supports your laminate flooring. If it is wood floors, you need to provide room for it to breathe in order to avoid moisture buildup. Also, if the subfloor is concrete, you have to cover the concrete floors with a moisture barrier to prohibit moisture from flowing up and reaching the laminate. Make sure that you scrub the subfloor well and it is already debris and dust-free because it needs to be clean before laying the moisture barrier underneath the laminate floor. Cut off any poking nails and sand down the high spots in wooden subfloors. Meanwhile, you can apply a self-leveling compound, for concrete subfloors, to level out any valleys.

Choose the Moisture Barrier

Selecting the appropriate moisture barrier that you will be using is a must. Moisture barrier paint and liquid is a common choice because it holds enough moisture.

Apply Moisture Barrier

Cut out your moisture barrier and lay it on the subfloor, then fasten pieces together using packing tape. It is important to have the plastic pieces overlap by a minimum of 8 inches. You can also paint the entire exterior surfaces using moisture barrier paint. With that, you can slowly proceed with the application under the laminate flooring. Another method of application is to spray the exterior cavities of the subfloor using spray foam. This kind of foam must be a closed-cell once you desired it as a moisture barrier. The moisture barrier will just level itself out. Begin with the farthest point of the room then toil your way out from the room.

Apply Fasteners

Once the insulation is finished, you need to place a 4 mil poly or plastic up above the exterior parts of the subfloor, which is under the laminate flooring. Employ a minimal quantity of fasteners to install properly the barrier underneath. Ensure corners are movable enough to put on sheetrock for wall sheathing. Allow moisture barrier to set for 24 hours.

Do the Final Set-Up

Ensure that the moisture barrier is properly installed to avoid any moisture later on. Take note that a liquid or paint moisture barrier has a strong odor, which is why during applications windows and doors should be open to allow air to circulate. Employ odorless mineral spirits to get rid of moisture barriers stick on your hands.