Cement board over sheet vinyl

[bjg5240]

What is the general consensus about installing hardi-backing tile board over the existing sheet vinyl? I thought I read this question before, but could not locate the post.

[TileLady]

It's not suggested. There's typically too much flex in sheet vinyl and this flexing will cause the hardi to flex and then affect the tile and grout (cracking tiles and/or grout).

Why not just rip out the sheet vinyl? I do it all the time and it's usually not that hard to get up. If you do tear out the sheet vinyl, you'll have to remove the adhesive left on the floor from the sheet vinyl, otherwise the mortar underneath the hardi won't stick to the floor.

[MattCoops]

Some people lay tile right over vinyl.
I call it a no-no. But it's done.

I don't know why you would want to lay backerboard over vinyl.
It's not too hard to remove vinyl. I don't think I ever broke a sweat from pulling up vinyl.
They even make scraper tools if the vinyl installer went crazy on the glue.

It's just so much more professional, and, well, better - to rip up the vinyl prior to a floor tile installation.

Your floor covering is only installed as good as what's underneath it.

[BACKWOODS]

I did my kitchen and laundry room a few years ago, laid Hardi over the vinyl. 460 sq ft. Screwed not nailed 60 screws per 3X5 sheet. I used 18 X 18 tiles, no problems. I used Mapei Ultraflex2 between backer board and vinyl, also used it to put tile down.

[Bill_Vincent]

This is copied and pasted from the floors page of my website:

This is a subject that's very hotly debated within the industry. It seems every manufacturer has a thinset that they say can be used over resilient flooring (sheet vinyl) or vinyl tile. The problem with that is twofold. With all the different types of vinyl flooring out now, it's tough to know which ones can, and which ones can't be tiled over. Cushioned vinyl's are out. They can compress, causing voids under the tile, ultimately causing failure. Also, not all sheet vinyl is glued solid to the floor. A lot of times, vinyl installers will only glue the edges and spot glue in the center, and if you thinset the tile to it, it won't stay very long. In my opinion, vinyl tiles are out, as well, due to the fact that the thinset bond is only as good as the bond of the surface under it, and I've seen vinyl tiles ( especially peel and stick) let go way too easily. The same is also true for sheet vinyl. The second problem with tiling over vinyl is the underlayments used for vinyl installation. Normally, in woodframe construction, there are one of several underlayments used-- luan, 1/4" particle board, 1/4" plywood, and sometimes even MDF (medium density fiberboard). ANY of those in a tile subfloor is a guaranteed failure. 1/4" plywood has a nasty habit of delaminating (the layers come apart). Luan has the same problem, plus it can compress to 1/2 its original thickness from normal residential foot traffic (I've seen this happen). Particle board (as well as MDF), just from humidity, can expand enough to pop tile loose. Any of those can cause failure, and unless you pull the vinyl, you don't know for sure whether the vinyl installer just went over the existing subfloor, or added one of the underlayments mentioned. All in all, it's an extremely risky installation, and my question is why, when spending the money it costs for a tile installation, would you want to gamble on it?

[bjg5240]

I've also read post where construction adhesive was used instead of thinset to set the cement boards. I can't imagine how much movement there could be when there is 50-60 screws/nails per 3x5 sheet. I'm not saying that this is what I plan on doing, I just wanted to pick some brains & see what the general thoughts were on this topic. Thanks!

[DavidC]

I did it once and didn't have any problem. (that I'm aware of) I can even list a title and author of a book that tells you it's OK.

But I won't do it again or list the book. The TCNA is my guide and their installation guide doesn't recommend it. I can do anything I want to at home, but when I work in someone else's home I want all installation problems to fall on the manufacturer whenever possible. Since they will always look to the installation as the first issue I'll go by the book.

Good Luck
Dave

[Bill_Vincent]

The reason for the thinset isn't to bond the cement board to the subfloor. It's there to act as a cushion of sorts-- fill the paper thin voids that would otherwise exist. Using constuction adhesive only serves to increase voids, rather than eliminate them.

[nwtile guy]

I agree with Bill on this one. Most of the vinyl flooring I have seen done up here is over particle board. Good luck installing tile over that. The problem isn't with the mortar sticking to the vinyl it is what is under the vinyl and how well it is stuck down. There is no way I would even consider tiling over vinyl. Why put your reputation on a highly questionable practice? Just my 2 cents.

[Floordude]

I can see the ill effects that can happen when tiles are set directly over non-cushioned sheet vinyl, and especially cushioned sheet vinyl. I do not see the ill effects with installing CBU over sheet vinyl, except is is going to take days for the thinset under the CBU, to dehydrate. Like Bill says, the thinset is not a bonding material, so much as it is a filler, to fill and support under the CBU and allow uncoupling properties.

I would weigh the risk, and put common sense to work. But something tells me, I wouldn't bat an eye going over noncushioned sheet vinyl, with CBU.

What's the difference... Mud bed & lath over roofing felt, or CBU over sheet vinyl.

[Bill_Vincent]

Originally Posted by Floordude

What's the difference... Mud bed & lath over roofing felt, or CBU over sheet vinyl.

1/4" versus 1 1/4".

Besides-- the lath reinforces the mud bed a whole lot better than the fiberglass in the cement board.

[New Generation]

Originally Posted by Bill_Vincent

The reason for the thinset isn't to bond the cement board to the subfloor. It's there to act as a cushion of sorts-- fill the paper thin voids that would otherwise exist. Using constuction adhesive only serves to increase voids, rather than eliminate them.

yup