Should We Install a Plywood Layer Over Concrete Before Installing Laminate Flooring?

When it comes to installing laminate flooring, achieving a level surface is crucial. This is particularly important if your subfloor is concrete, which can often present some challenges due to its uneven nature.

Preparation of Subfloor

First, evaluate the condition of your subfloor. If it is not already level, you will need to address this issue before proceeding with laminate flooring. In cases where the subfloor is concrete, you typically have two options: applying a self-leveling compound or installing a plywood layer.

In my own project, I chose to use a 1/4 inch, 5-ply plywood to level a slightly wavy wood subfloor. If concrete was present, I would have needed to use a leveling compound. In my specific case, a combination of levelling compound and plywood was required to achieve the necessary level surface.

Self-leveling compounds are often easier to use and can be sourced from big-box stores. However, if you have a significant budget and are prepared to make some modifications such as trimming door frames and possibly relocating or replacing wall baseboards, consider using thicker plywood. Proper leveling with shims may also be necessary for the thicker plywood.

Sealing Concrete

It’s important to note that if you are working with a concrete subfloor, sealing the surface is crucial. This step helps prevent moisture from rising up into the space and potentially damaging your laminate flooring. For the best results, you should seal the concrete surface using a high-quality sealer and apply it several times.

Leveling Concrete Subfloor

Before applying the plywood layer, ensure that your concrete subfloor is level. One effective method is to use a long, straight board or metal to mark any areas that show more than an 1/8 inch deflection. These areas should be ground down, and the low spots should be filled to create a smooth, level surface.

After leveling, consider installing a vapor barrier, such as a 6-mil polyethylene film, as recommended by the manufacturer. This step is crucial in preventing moisture buildup and ensuring the longevity of your laminate flooring.

Conclusion

While it may not be necessary in some cases, adding a plywood layer over a concrete subfloor is a reliable solution for achieving a level surface, which is crucial for successful laminate flooring installation. Always follow the manufacturer's instructions and invest in quality materials. By taking the necessary steps, you can ensure a stunning and durable floor for your home.