Can I install backerboard over linoeum?

I got 2 estimates for tiling our kitchen and bath areas. One place will rip out the existing linoleum, put down backer board and tile but doesn't remove/replace the trim/base boarding. The other will remove and replace the trim/base boarding, but installs the backer board over the existing linoleum. They said its not a problem because they really screw down the backer board and that's the way they do it, all the time. What's the opinion of this forum? Ok to leave linoleum or should it be removed? I may do it myself, but haven't decided yet.

 

What's under the linoleum?

 

Get rid of it. I am less worried about the baseboards as shoe molding will cover the needed gap along the perimeter. The linoleum has some give to it, which is bad for tile and cement which likes no give. You also have a 1/4 of plywood or luan under the linoleum which does not add any structural strength to the floor and (if luan) may have a delaminating problem down the road if presented with moisture from a leak at the dishwasher or sink.

Most flooring with linoleum are 5/8" ply which is pushing the absolute minimum for tile. Again, the 1/4" and the cement board add nothing to the mix as far as structural strength. So you are still looking at minimums.

Not counting your floor joists size, spacing and span - Ideally, I try to get 1/2" ply, covered with 3/4" Advantech, thinset, 1/4" cement board, thinset, and then your tile. In your case, 5/8" plus 1/2"ply, thinset, 1/4" cement board, thinset, and then your tile.

 

thanks for the ino. its a stick built house, built by a pretty good builder in the area, with a basement, but I don't know whats under the linoleum other than plywood.... not sure how thick or layers.
Why the thinset between the ply and cement board? I don't think either estimate included that... just screwing down the cement board every 12 inches.

 

It provides for optimal support of the cement board above and adjusts the ply to make up for any dips and voids below. Again, the 1/4" is not structural, so it will flex if there is flex below. Setting the cement board in a troweled bed of thinset will fill in and better support the floor that will go on top. I've seen floors where the homeowner went behind the tile guys and added additional screw - effectively making it every 6" on center with the screws. The floor crackled and creaked when you walked across it 5 years later. It is an important step, if the tile guys you are working with refuse or tell you it is not needed, I would consider additional bids.

1 - loose the company who wants to tile over the linoleum
2 - loose the other company if they don't set in a mortar bed, but you can forgive them on the baseboards - although, I think it is lazy not to pull them. But that is just me.

If they pressure you, Let me know and I will search out the links to the Tile Institute of America that sets the standards for tile installation and get those to you.