Cushioned Vinyl Over Old Tile: The Grout Line Problem

I was on my knees in the half bath on a Sunday morning, scrubbing grout with an old electric toothbrush because apparently that’s a thing now, apparently that’s what qualifies as self care in my life these days, and I had a solid ten minutes to just stare at the floor while the bristles did their thing. Gray grout, white hexagon tile, the kind that came with the condo and that I have complicated feelings about. And somewhere around minute six I thought, not for the first time, that I should just cover the whole thing. Cushioned vinyl, the sheet kind, the kind that feels soft under bare feet in a way tile never will at six in the morning in February. Rip nothing out. Lay it right over what’s already there.

On paper it’s the efficient move, less demo, less dust, less of my Saturday gone to a project that technically isn’t even visible to anyone but me and whoever’s unlucky enough to use my guest bathroom.

Except I’d seen photos online of exactly this kind of install gone wrong, and I want to be specific about what “wrong” means here because it’s not the floor falling apart or lifting at the edges. It’s grout lines. Faint gray gridlines showing up through the vinyl a few months later like the tile is still in charge underneath, like you didn’t actually cover it, you just put a thin sheet over an argument you didn’t finish having. And once I saw that in someone else’s kitchen photo, on a forum thread I fell into instead of doing actual work one evening, I couldn’t unsee the possibility in my own bathroom.

This isn’t a checklist post. I’m not going to hand you five bullet points and tell you cushioned vinyl over tile is a yes or a no, because it’s neither, it’s a “depends how much you’re willing to do first” and that answer is genuinely more useful than a clean verdict, even if it’s less satisfying to read. What I want to actually get into is why the grout lines show through in the first place, what prep actually closes that gap, and where the line sits between reasonable weekend project and a job you should’ve just paid someone for. Because I’ve thought about this floor longer than I’ve thought about some real financial decisions, and I have the notes to prove it.

[Cushioned Vinyl Over Old Tile]

Why the Grout Lines Show Up At All

Here’s the thing that took me embarrassingly long to understand. Cushioned vinyl is soft on purpose, that give under your feet is the entire selling point, and that softness is exactly what betrays you. A rigid material sitting on top of tile can bridge a grout line without ever announcing it’s there. A cushioned material can’t, not fully, because it’s designed to flex and compress with weight, and grout lines are a change in surface height even when they feel flat to your hand. We’re talking a difference that might be a sixteenth of an inch, sometimes less, and a rigid product shrugs that off. A cushioned one will slowly, over weeks of foot traffic, start to press down slightly into that low spot until the pattern of the tile underneath becomes visible as a faint grid, sometimes called telegraphing, which is a genuinely accurate name for a genuinely annoying problem.

It doesn’t happen on day one. That’s the part that gets people, because they lay the floor, it looks perfect, they post the after photo, and three months later the grid is back like the tile never left. The forum thread I mentioned earlier had exactly that arc, a beautiful before and after, then an update further down with a photo of the same kitchen looking like someone had drawn a faint tic tac toe board across it in pencil. Not a manufacturing defect. Not bad luck. Just physics doing what physics does when you skip a step, which brings me, predictably, to the step everyone wants to skip.

[Grout Line Telegraphing]

Skim Coating Is the Actual Job, Not the Vinyl

If there’s one thing I’d want someone to take from this whole piece, it’s that the vinyl is not the project. The floor prep is the project, and the vinyl is just the part you get to enjoy at the end. A proper skim coat, a thin layer of floor leveling compound spread across the entire tile surface to fill the grout lines flush with the tile itself, is the difference between a floor that stays flat and one that quietly reveals itself later.

I want to be honest about the labor here because a lot of what I read online undersold it. This isn’t a quick pass with a putty knife. You’re mixing compound to a specific consistency, spreading it thin enough that it doesn’t build up unevenly, feathering the edges so you don’t create new high spots to replace the old low ones, and then sanding, sometimes more than once, because the first pass never gets it perfectly flat, not for me and not for anyone I’ve read about doing this honestly instead of for content. For my half bath, roughly forty square feet, that was two full evenings before I even got to think about the vinyl itself. On paper it’s a Tuesday and Wednesday after work. In reality it was a Tuesday, a Wednesday, and an unplanned Saturday morning because the first coat dried thinner in one corner than I expected and left a shadow of a line I could still feel with my palm. I redid it. I am not too proud to say that.

The tile also needs to be structurally sound before any of this starts, no loose tiles, no hollow sounding spots when you tap around, because a skim coat over a tile that’s already failing is just hiding a second problem under the first one.

[Skim Coating and Leveling Compound]

The Underlayment Question Nobody Answers Straight

Cushioned vinyl comes with an assumption baked into it that the subfloor underneath is smooth, and tile, even after a skim coat, is a slightly more aggressive test of that assumption than a plain plywood subfloor would be. Some manufacturers will tell you their product can go directly over tile with sufficient leveling. Others will tell you flat out not to, full stop, warranty void, don’t even try it. I called the woman two desks over at work about this, not because she knows flooring, she doesn’t, but because she’d just redone her own kitchen and I wanted a second person’s Saturday to compare mine against. Hers took four days longer than planned because her installer insisted on an additional underlayment layer over the leveled tile before the vinyl went down at all, a thin fiber based product specifically meant to add one more buffer between old imperfections and new soft flooring.

That extra layer isn’t universal advice and I’m not going to pretend it is, because it depends on the specific vinyl product and how thick and self leveling your skim coat actually turned out. But it’s worth checking your product’s actual installation guide line by line rather than assuming cushioned vinyl behaves like the rigid vinyl plank everyone’s Pinterest board is full of. They are not the same install, they are not the same tolerance for imperfection, and treating them the same is exactly how the grid pattern comes back to haunt you around the six month mark, right when you’ve stopped checking.

[Underlayment for Cushioned Vinyl]

Drying Time Is Not a Suggestion

I am, by nature, a person who reads the recommended cure time on a bag of leveling compound and treats it as a floor, not a ceiling, meaning I assume I can beat it if I’m careful. This is a bad instinct and I want to actively talk you out of it. Leveling compound that hasn’t fully cured will still have moisture moving through it, and vinyl flooring, cushioned or otherwise, does not want to be laid over a surface that’s still working through that process. You trap moisture under a vinyl sheet and you’re not looking at grout lines showing through anymore, you’re looking at bubbling, lifting, in a worst case scenario mold nobody wants to discover eighteen months later during an unrelated project.

I did a moisture test before laying anything, taped a small square of plastic sheeting to the floor overnight and checked for condensation underneath the next morning, which is not sophisticated equipment, it’s a twelve dollar afternoon of patience, but it told me what I needed to know. My skim coat needed an extra full day beyond what the bag suggested, because my bathroom runs humid from actual daily use, which the compound manufacturer obviously didn’t account for when writing generic drying guidance for a generic house that doesn’t exist. The whole project sat idle for a day longer than my plan allowed, and I minded that more than I probably should have, given the actual stakes of a bathroom floor being one day later than scheduled.

[Moisture Testing and Cure Time]

When Ripping It Out Is Just the Better Math

Somewhere around hour three of sanding a skim coat that wasn’t cooperating, I did the version of this project that exists purely in a spreadsheet, cost of leveling compound and tools and my own time valued at approximately nothing because I already own a full time job that pays me properly for my hours, against the cost of just hiring someone to pull the tile and start from bare subfloor. For a small bathroom, that math tips toward doing the prep yourself pretty quickly, because tile removal on top of everything else adds real demo cost and real mess for a room that size.

For a larger space, an actual kitchen, a full bath with a tub surround involved, the math flips. Old tile that’s cracked, hollow sounding in multiple spots, or laid over a subfloor with its own problems is not a good candidate for skim coating your way out of trouble, it’s a candidate for removal, and pretending otherwise to save a weekend is how you end up doing this whole process twice.

I’ve made that decision correctly once and would have made it incorrectly a second time if the estimate for full removal on a friend’s kitchen hadn’t come back close enough to the DIY leveling route that skipping the demo stopped making obvious sense. Sometimes the honest answer to “can I skip removing the tile” is technically yes, and separately, financially, you shouldn’t.

[Tile Removal Alternative]

Final Thoughts

I keep coming back to the fact that none of this is really about vinyl at all. The flooring is the easy part, the part you actually enjoy, laying it down, watching a tired bathroom look finished in an afternoon. The actual work, the part that determines whether you’re happy with this floor in a year or quietly annoyed by a faint grid pattern every time you’re standing at the sink, happens entirely before the vinyl shows up. Skim coating properly, choosing the right underlayment for your specific product, respecting drying times that don’t care about your schedule, and being honest with yourself about when the tile underneath is too far gone to build on top of.

None of that is glamorous, and none of it photographs well for the kind of before and after post that made me want to do this in the first place. But it’s the difference between a floor that just works and one that reminds you, every few months, that you took a shortcut somewhere back at the start. I don’t regret covering my tile instead of ripping it out. I do regret, slightly, how long I resisted believing the prep work mattered as much as everyone kept saying it did.