You can put peel and stick tile over existing vinyl, but there are certainly right and wrong ways to do it. If the underlying vinyl isn’t in good condition, you won’t be very happy with the results. And if you don’t do any prep work, you won’t be very happy with the results.
I’ve seen this go well, and I’ve seen it go poorly. Here are the secrets that allow it to go well.
Inspect the existing floor
First, there’s not much point in putting a layer of peel-and-stick over another layer of peel-and-stick. If you do that, then you have two layers that can fail instead of one. The only time I’ll put peel and stick tile over existing tile is to cover 9-inch tile, which is likely to contain asbestos. But when covering suspected asbestos, I really prefer some type of floating floor. That way, if something ever happens to the floor above the asbestos, I have more options.
If the existing floor is a single sheet of vinyl, you have to ask yourself what’s wrong with it. If it’s in good shape and just out of style, it’s a good candidate to cover. If it’s beat up, you need to correct that before you cover it. Peel and stick tile will conform to any flaws that exist underneath it. I haven’t tried this myself, but a carpenter I know told me that if you put a coin under a vinyl floor, after a year you’ll be able to read the date on it.
Clean the floor
You need to clean the floor before you fix it, but you need to determine how much work it’s going to take first. If it’s going to take more than a quart of floor leveler to fix it, I prefer to remove it. Why waste time cleaning something you’re going to need to remove?
Cleaning the floor is essential. Vinyl adhesive will stick to the dirt, grease, and other contaminants. Eventually, the contaminants will loosen from the floor and cause the adhesive to lift. I saw that with the first vinyl floor I ever replaced. Someone had laid a pretty nice vinyl floor in a kitchen, but a lot of the tiles were lifting. I found a really greasy floor underneath those nice tiles.
So, before proceeding much further, sweep or vacuum the floor thoroughly. Then open the windows and mop the floor with ammonia. I go so far as to use two mop buckets. I fill one bucket with ammonia and use the other to wring out the mop so I spread less dirt around with the mop.
Correct flaws in the underlying floor
If the existing vinyl has holes in it, fill the holes. I use premixed floor leveler. It’s relatively inexpensive and easy to use.
Just scoop out enough leveler to fill the hole. Then use a putty knife or trowel to make it smooth with the floor and let it dry.
If the floor is too far gone and you can afford to raise the floor about 1/8 of an inch, lay down some plywood underlayment over the existing floor and put your vinyl tiles over that. Or just use a floating floor instead.
Some people put down a chalk line through the middle of the floor to give themselves a guide. I find I can usually use the existing pattern to guide the tiles. Start placing tiles from the middle of the floor and work your way to the edges. Don’t work from two sides of the room and try to meet in the middle. It never matches up. Work from the middle out, so your gaps are all at the edge along the wall, where you can correct them without disrupting the pattern.
Prime the floor
The secret to long-lasting vinyl tile floor is to prime it with the right stuff. I use VCT adhesive. Put down a thin coat, leaving a path along one or two edges for yourself to leave the room. Let the coat dry until it’s translucent, which can take a few hours. It should be tacky but not wet. Then lay your tiles. Go right up to the wall–you don’t need an expansion gap.
Once you have your tiles down, prime the path you left, then exit the room via the tile. Come back when that adhesive is dry and finish.
Roll the floor
You’ll get better results by renting a heavy duty floor roller, but at the very least, use an extensible floor roller to roll the tiles down. The pressure helps the tiles stick down better for a longer-lasting floor. I’m pretty sure you don’t want to do this again in a year.