LVT Flooring Let me be straight with you—If you’ve ever worked with vinyl flooring of any kind, or even watched a neighbor install a floor themselves, you’ve probably heard the question: Is prep work worth the time? As someone who’s been supplying LVT (luxury vinyl tile and plank) to contractors, home renovators, and DIYers for the past 12 years, I’ve seen it all. I’ve pulled up half-installed LVT that looked like it was laid on a warped plywood scrap, fixed gaps in seams that showed up 6 months later, and even replaced entire LVT jobs because the subfloor was so uneven the planks popped loose within a month. Today, I’m here to set the record straight: Yes, you absolutely need to prepare your surface before installing LVT flooring. No exceptions. I’m not just saying this because I sell LVT—though I’d be lying if I didn’t admit proper prep leads to fewer returns, happier customers, and more long-term referrals for my business. I’m saying this because I’ve seen exactly what happens when you skip this step, and it’s never pretty. Let’s break down why surface prep for LVT is non-negotiable, what happens if you cut corners, and exactly how to do it right, so you can get a floor that looks good, lasts, and saves you from expensive headaches later. First, let’s talk about what LVT actually is, because that changes the game. A lot of people confuse LVT with old sheet vinyl or even cheap laminate. LVT is a rigid-core (or sometimes flexible-core) flooring product that has a printed design layer, a wear layer, and a backing layer. Most modern LVT is click-lock, meaning the planks or tiles snap together without adhesive, and it sits loose on top of the subfloor. That click-lock system is what makes LVT so popular—easy to install, quiet underfoot, water-resistant. But here’s the catch: That same click-lock system is only as good as the surface it’s sitting on. If your subfloor has bumps, dips, debris, or moisture, those tiny click-lock edges, which are meant to lock tight, won’t seal properly. The planks will shift, gaps will form, and when you step on them, they’ll squeak, sag, or even pop up. I remember a customer from last year—she bought 1,200 square feet of my commercial-grade LVT for her small retail store, decided to save a few bucks by skipping prep and laying it directly over her old linoleum. Within 3 weeks, the middle of the floor had a “bounce” you could see when you walked across it. The old linoleum had a loose spot under the register, the LVT planks over it flexed too much, and the click-lock seams split. She ended up ripping the whole thing out, paying for a professional subfloor repair, and buying another batch of LVT from me. She saved $200 on a prep service, but lost $4,000 total in rework and extra product. That’s the story I tell every time someone asks if prep is necessary—because it’s not an opinion, it’s a real, expensive lesson. Now, let’s get specific about what kind of surfaces you can (and can’t) install LVT over, and what prep each needs. The first rule of LVT surface prep is: The flatter and drier your subfloor, the better. If your subfloor has more than a 3/16-inch deviation over 10 linear feet (that’s roughly the width of a standard doorway), you have to level it. That’s not a random number—most LVT manufacturers’ installation guides (including the ones I follow as a supplier, since I stand behind the products I sell) list that as the maximum allowable unevenness. Why? Because a dip of more than that means there will be gaps under the planks, and when weight is applied, the plank will bend where there’s no support. A bump of more than that will cause the same flex, and you’ll hear a “thud” every time you step on that spot. Let’s go through common subfloors and their needs: First, concrete subfloors—super common in basements, garages, and new construction. If you’re installing LVT over concrete, the two biggest issues are moisture and contaminants. Concrete is porous, so it lets moisture vapor rise up through the slab. For below-grade concrete (like basements), you need a vapor barrier—usually a 15-mil plastic sheeting or a specialized moisture mitigation product—to stop that moisture from getting under your LVT. Even if your concrete feels dry to the touch, that doesn’t mean there’s no vapor. I’ve had customers tell me their concrete “feels totally dry” but after installing LVT, they noticed the wear layer bubbling after a few months because of trapped moisture. Contaminants on concrete? Things like old paint, oil, glue, dust, or even leftover mortar. Those will create a barrier between the LVT and the subfloor, so the planks can’t sit tight. I always tell my clients to clean concrete with a concrete grinder or a heavy-duty floor sander to get rid of anything sticky or rough, then vacuum and mop with a pH-neutral cleaner to get rid of fine dust. Next, plywood subfloors—common in above-grade homes, second floors, and additions. Plywood is a stable subfloor, but it has two big prep issues: gaps between sheets, and unevenness from protruding nail or screw heads. If there are gaps between plywood sheets (even small ones), that means there’s a hollow spot under your LVT plank, which will cause sagging or squeaking over time. Nail heads that stick up can scratch the bottom of your LVT, or even make the click-lock edge catch, breaking it. For plywood, you have to start by screwing down any loose sheets—old nails often pop up as the house shifts, so replacing nails with 1 5/8-inch screws (long enough to go through the plywood and into the floor joists) will secure everything. Then, you have to fill gaps between sheets with a floor-leveling compound or a thin coat of joint compound, and sink any protruding fasteners so they’re 1/8-inch below the plywood surface. A lot of DIYers make the mistake of just putting a screw over a nail head, but if it’s not sunk, it will still cause a problem. Then there are existing flooring surfaces—like old vinyl, laminate, or tile. This is where I get the most questions, because people love the idea of laying LVT over their old floor to save time. But here’s the rule: You can only install LVT over existing flooring if that existing floor is hard, flat, and free of damage. If your old tile has loose grout or cracked tiles, you have to remove it first. If your old vinyl has any soft spots, tears, or is curling up at the edges, that has to go. I had a customer last year who tried to lay LVT over old ceramic tile in his bathroom. The tile had a few hairline cracks, and the grout between the tiles was uneven. Within 2 months, the LVT planks over the cracked tile had a visible line where the plank was compressed, and the grout roughness had scratched the bottom of the planks. He had to pull everything out, replace the tile, and start over. The only time I recommend laying LVT over an existing floor is if that floor is a fully adhered, smooth sheet vinyl that’s in perfect condition—no tears, no bumps, no curling. Even then, I always advise a light sanding to rough up the surface so the LVT adhesive (if you’re using glued-down LVT, which is common for high-traffic areas) will stick better. Now, what if you skip surface prep? I’ve already told you about the bounce and the split seams, but let’s get into the long-term issues, because that’s what really matters. LVT is supposed to last 15 to 25 years, right? But if you skip prep, you’re lucky if it lasts 5 years. Squeaks and squeals in LVT? Usually from uneven subfloor or loose click-lock edges because of poor support. Gaps between planks? That’s from shifting due to unevenness or debris under the floor. Mold or mildew growth? That’s from trapped moisture because you didn’t use a vapor barrier on concrete, or left a wet subfloor. Scratches on the LVT wear layer? Often from protruding fasteners or rough subfloor bumps. And here’s one I see a lot: indentations. If you have a uneven subfloor, when you place heavy furniture (like a couch or a fridge) on the LVT, the planks over the dip will compress, leaving a permanent indent. That ruins the look of the floor, and it’s almost impossible to fix. I once supplied LVT for a rental property where the landlord skipped prep, laying it over uneven plywood. Within a year, every room had indentations from the tenants’ beds and dressers, and he had to replace the entire floor when he put it up for sale—because the dents made the house look cheap, and new buyers wouldn’t accept it. Now, let’s talk about how to do surface prep correctly, so you can avoid all of that. I’ll break this down into simple, step-by-step steps, based on the subfloor type, so you don’t have to guess. First, always start with a thorough inspection. Walk the entire space, mark any dips, bumps, gaps, or damaged areas with a pencil. For unevenness, the easiest way to check is with a 4-foot level—place it on the floor, and slide it around. If there’s a gap larger than 1/8-inch under the level, you have an uneven spot that needs leveling. For concrete, you can also use a moisture test—buy a simple calcium chloride test kit (they’re cheap, and available at any hardware store) and follow the instructions to test vapor emissions. If the test shows more than 3 pounds of vapor per 1,000 square feet over 24 hours, you need a moisture mitigation product for concrete. Next, cleaning. No matter what subfloor you have, you have to get it 100% free of debris. Dust, dirt, and tiny pebbles might seem harmless, but they act like little rocks under the LVT, creating uneven spots and scratching the bottom of the planks. For concrete, use a concrete grinder to remove any glue, paint, or old mortar, then vacuum with a HEPA vacuum (regular vacuums leave fine dust that’s hard to get rid of). For plywood, scrape off any old adhesive or paint, then vacuum and mop with a warm, soapy water solution (no harsh chemicals, because they can leave a residue). For existing flooring, if you’re keeping it, wipe it down with a degreaser and sand lightly to rough up the surface. Then, leveling. If your subfloor has unevenness over 3/16-inch, you need a floor-leveling compound. For concrete, use a self-leveling compound designed for concrete, which spreads evenly and dries in 24 to 48 hours. For plywood, use a leveling compound made for wood, or fill deep gaps with a thin patch of plywood cut to fit, screwed down securely before covering with leveler. Always follow the manufacturer’s instructions for mixing and drying—don’t rush this step, because if the leveler isn’t fully dry, it can trap moisture under your LVT. For plywood, another quick fix: if you only have small, protruding nail heads, you can use a floor sander to sand them down level, instead of using a leveler. But if you have multiple uneven spots, leveling compound is the easier, more consistent option. Finally, vapor barrier if needed. For below-grade concrete (basements, ground-floor slabs), you have to lay a 15-mil plastic sheeting over the entire concrete, overlapping seams by 6 inches, and taping the seams with duct tape to make a complete barrier. Some LVT manufacturers recommend a specialized moisture membrane instead of plastic, which is more durable for high-moisture areas, but plastic works for most residential basements. For above-grade concrete, a vapor barrier is still a good idea, even if you don’t think you need it—acclimate your LVT to the room for 48 to 72 hours before installing it, which lets the planks adjust to the temperature and humidity of the space, so they don’t expand or contract after installation. Wait, acclimation is part of prep, right? I forgot to mention that. A lot of people skip acclimation, which leads to gaps in the planks or buckling later. LVT is made of vinyl, which expands and contracts with changes in temperature and humidity. If you install planks that were stored in a cold garage into a warm living room, they’ll expand as they warm up, and buckle. If you install planks that were stored in a dry space into a humid basement, they’ll contract, leaving gaps. So acclimation is a key part of surface prep too—let the LVT sit in the room where it’s being installed for at least 48 hours, with the boxes open, so the planks can adjust to the room’s conditions. I always tell my customers that prep takes 20% of the total installation time, but it’s 80% of the success of the floor. I’ve had a contractor who used to skip prep on every job, because he said it “wastes time and money.” Now, he comes to me every week to buy LVT for commercial jobs, because after he skipped prep on a 10,000 square foot office space, the owner had to pay $15,000 to fix the LVT and redo the subfloor. He now budgets for prep on every job, and his customer ratings have gone up 50% because his floors last longer. Let’s be real—when you’re installing LVT, you want a floor that looks good right away, and looks good for years. You don’t want to be calling a repairman a month after installation because your planks are squeaking or popping up. You don’t want to deal with a customer who’s upset because their new floor has gaps or indentations. And as a supplier, I want my customers to be happy with their LVT, come back to buy more, and recommend me to other contractors and homeowners. So when someone asks me, “Do I need to prepare the surface before installing LVT flooring?” my answer is always: Yes, absolutely. But it doesn’t have to be complicated or expensive. You just have to take the time to check your subfloor, fix the uneven spots, clean it thoroughly, and make sure it’s dry before you lay your LVT. If you do that, you’ll have a floor that’s beautiful, durable, and gives you zero headaches for years to come. If you’re planning an LVT installation and have questions about surface prep, or need to order the right amount of LVT or prep products for your project, feel free to reach out to discuss your specific needs. I’m here to help you get the job done right, the first time.
REFERENCES LVT Flooring
- National Wood Flooring Association. (2021). Installation Guidelines for Luxury Vinyl Tile (LVT). NWFA Standards of Practice.
- Floor Covering Installers Association (FCIA). (2022). LVT Subfloor Preparation Requirements. FCIA Residential Installation Manual.
- Vinyl Institute. (2020). Moisture Mitigation for Luxury Vinyl Flooring. Technical Bulletin MB-003.
- Armstrong Flooring. (2021). Installation Handbook for Rigid Core LVT. Product Specification Document.
- Shaw Industries. (2022). Subfloor Preparation Best Practices for LVT and LVP. Residential Installation Guide.
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