How To Level Plywood Floor For Vinyl Plank Flooring

Installing vinyl plank flooring (VPF) over a plywood subfloor offers a durable and aesthetically pleasing surface. However, the success of a VPF installation hinges critically on the flatness and evenness of the subfloor. Imperfections in the plywood, such as uneven seams, dips, humps, or nail pops, will telegraph through the relatively thin vinyl plank, leading to an unsightly and potentially unstable floor. Therefore, properly leveling the plywood subfloor is a mandatory step for a professional-looking and long-lasting VPF installation.

This article provides a comprehensive guide on how to level a plywood subfloor in preparation for vinyl plank flooring. It covers assessing the floor's condition, identifying problem areas, and employing various techniques to achieve a sufficiently flat and smooth surface that meets the stringent requirements of most VPF manufacturers. The specific methods employed will vary depending on the severity of the unevenness and the overall condition of the plywood.

Assessing the Plywood Subfloor

Before commencing any leveling work, a thorough assessment of the existing plywood subfloor is essential. This involves visually inspecting the floor and identifying any areas of concern. The assessment should include checking for loose or damaged plywood sheets, protruding nails or screws, uneven seams, and variations in height across the floor. A key component of the assessment involves determining the extent of the undulation using specialized tools. This assessment forms the basis for determining the appropriate leveling strategies.

Visual Inspection: Begin by carefully examining the entire plywood surface. Look for signs of water damage, such as staining, warping, or delamination. Pay close attention to the seams between the plywood sheets, as these are common areas for unevenness. Check for any loose or broken pieces of plywood. Also, scrutinize the perimeter of the room, paying attention to the area where the subfloor meets the walls. Look for gaps or areas where the plywood is not properly supported.

Check for Fastener Protrusions: Walk across the entire floor, paying close attention to the feeling underfoot. Any protruding nails or screws must be identified and addressed. These can either be hammered back into the plywood or, preferably, removed and replaced with screws that are countersunk slightly below the surface of the plywood.

Using a Straight Edge: A straight edge, preferably a long one (at least 6 feet) is an invaluable tool for identifying high and low spots in the floor. Place the straight edge on the plywood surface in various directions, both parallel and perpendicular to the seams. Use a level in conjunction to determine the severity of undulation. Look for gaps between the straight edge and the plywood. The larger the gap, the more significant the unevenness. Mark these areas with a pencil for later attention.

Using a Long Level: A long level can also be used to identify variations in floor height. Place the level on the floor and observe the bubble. If the bubble is not centered, it indicates that the floor is not level in that direction. Move the level around the room and note any areas where the floor is significantly out of level. These areas will require additional leveling work.

Measuring Undulations: For a more precise measurement of undulations, a laser level is often employed. This involves using a laser level to establish a reference plane across the room and then measuring the distance from the laser beam to the plywood surface at various points. This data can then be used to create a contour map of the floor, highlighting areas of high and low elevation. This precise measurement is particularly useful for larger rooms or areas with significant unevenness.

Addressing Minor Imperfections

Minor imperfections, such as small dips, shallow seams, and slightly raised nail heads, can often be addressed with relatively simple techniques. These techniques aim to create a smooth and uniform surface without resorting to major reconstruction. The strategies typically involve sanding, using patching compounds, and securing loose fasteners.

Sanding: Sanding is an effective way to smooth out minor imperfections and feather the edges of slightly raised seams. A power sander, such as an orbital sander or a drum sander (for larger areas), equipped with medium-grit sandpaper (80-100 grit) is typically used. The key is to apply even pressure and move the sander in a consistent pattern to avoid creating new dips or gouges. Before sanding, ensure that all nails and screws are properly set to avoid damaging the sandpaper.

Patching Compounds: For small dips and imperfections, patching compounds designed for wood floors are ideal. These compounds are typically cement based and can be applied with a trowel or putty knife to fill in the low spots. Follow the manufacturer's instructions for mixing and application. Allow the compound to dry completely before sanding it smooth to blend with the surrounding plywood. Several thin layers are preferred over a single thick layer to prevent cracking.

Securing Loose Fasteners: Loose nails or screws should be addressed promptly. Ideally, remove the existing fasteners and replace them with screws that are long enough to penetrate deeply into the floor joists. Countersink the screws slightly below the surface of the plywood to avoid creating bumps. If the existing holes are too large to hold the new screws securely, fill them with wood filler before inserting the screws.

Seam Treatment: Uneven seams can be addressed by first sanding down any high spots. Then, apply a thin layer of patching compound to fill in any remaining gaps or depressions. Feather the edges of the compound to create a smooth transition between the plywood sheets. Once the compound has dried, sand it smooth to create a seamless surface.

Vacuuming and Cleaning: After sanding and patching, thoroughly vacuum the entire floor to remove all dust and debris. This is crucial to ensure proper adhesion of the vinyl plank flooring. Wipe the floor with a damp cloth to remove any remaining residue. Allow the floor to dry completely before proceeding to the next step.

Addressing Major Unevenness

In cases where the plywood subfloor exhibits significant unevenness, such as large dips, pronounced humps, or areas where the plywood is severely damaged, more extensive leveling techniques are required. These may involve using self-leveling compounds, installing plywood shims, or even replacing sections of the subfloor.

Self-Leveling Compound: Self-leveling compound (SLC) is a cement-based mixture that, when poured onto the floor, spreads out and levels itself due to gravity. It is an effective way to address large areas of unevenness. Before applying SLC, it is crucial to prepare the floor properly by cleaning it thoroughly and applying a primer recommended by the SLC manufacturer. The primer helps the SLC bond properly to the plywood. Dams may be required to contain the SLC in the designated area as it can flow out. Follow the manufacturer's instructions carefully regarding mixing ratios and application thickness. Once poured, use a spiked roller to remove any trapped air bubbles. Allow the SLC to cure completely before installing the vinyl plank flooring.

Plywood Shims: For localized dips or low spots, plywood shims can be used to bring the subfloor up to the desired level. Cut the shims to the appropriate size and shape, and then glue them to the plywood subfloor using construction adhesive. Secure the shims with screws to prevent them from shifting. Once the adhesive has dried, sand the shims smooth to blend with the surrounding plywood. This method is particularly useful for addressing dips along walls or around pipes.

Replacing Damaged Plywood: If sections of the plywood are badly damaged, water-stained, or delaminated, it is best to replace them entirely. Carefully cut out the damaged section using a circular saw, being careful not to damage the surrounding plywood or the floor joists. Install a new piece of plywood of the same thickness, ensuring that it is properly supported by the floor joists. Secure the new plywood with screws, and then sand the seams smooth to blend with the existing subfloor.

Reinforcing the Subfloor: In some cases, the plywood subfloor may be too thin or too flexible to provide adequate support for the vinyl plank flooring. In these situations, it may be necessary to reinforce the subfloor by adding an additional layer of plywood. This will increase the overall stiffness of the floor and prevent the vinyl plank flooring from flexing or cracking. The new layer of plywood should be installed perpendicular to the existing plywood, and it should be secured with screws spaced every 6-8 inches.

Checking for Proper Deflection: Regardless of the leveling method used, it is essential to check for proper floor deflection before installing the vinyl plank flooring. Excessive deflection can cause the vinyl planks to crack or separate. To check for deflection, place a heavy object, such as a refrigerator or washing machine, on the floor and observe how much the floor flexes. If the deflection is excessive, additional reinforcement may be necessary. Consult with a qualified contractor or structural engineer for advice on how to properly reinforce the floor.

By following these steps, a level and stable plywood subfloor can be achieved, ensuring a successful and long-lasting vinyl plank flooring installation. Remember to prioritize safety by wearing appropriate personal protective equipment, such as safety glasses and a dust mask, when working with power tools and patching compounds. Consulting with a professional flooring installer is recommended for complex or challenging projects.