Tile over tile

[Andrew Charles Eddy]

Ok hear me out. I have read quite a bit about tiling over tile and from what I understand it is not generally a good idea because you do not know what is under the old tile, if it is structurally sound and if there are leaks or rotting. I am asking because I have recently purchased a small 10 room Inn that is quite old but all the bathrooms were renovated last year (2018).

The bathrooms have new floor tile and new walk-in showers (converted from tubs) with a curb. The contractor did a good job and clearly has a lot of experience. Unfortunately, the style and design go against our brand and we need to update the bathrooms including new vanities, toilets, fixtures, and floor and shower tile.

I know some will think it is a waste of money and that the tile looks good (I will include pictures) but switching the tile is non-negotiable so...

What do you think about tiling over the old floors and showers? I am not concerned about the lost 1/2" of space. I am concerned about additional weight on the subfloor (a few of the rooms are on the upper level).

To rip out all the new and freshly laid tile (Some is on concrete subfloor so....) and take the showers down to the studs and rebuild the pans ect... will cost a ton of money because I have to do 10 of them. On top of that, we are talking about a week of work per bathroom at least of additional work. What are everyone's thoughts? Pictures below.

 

[WorthFlorida]

Your images didn’t load. Drag and drop works best or link to a photo site if the files are too large.

If there are already two layers of tile I would not put down a third. From the outer room to the bathroom you have a high lip where guest can trip. Then it will cost more than tearing out tile. As you stated the weight can become an issue if you’re on wood frame floor. The floor might flex under the weight of tile and people then the tile will crack. Without seeing the structure it’s a hard call.

 

[Sponsor]

 

[Cacher_Chick]

Everything is dependent on the structure, and right now you don't know if deflection is going to be a problem or even if the existing showers were properly waterproofed. I would gut one of the upper floor baths to get a good idea of what is hiding there and then you would be able to use better judgement as to how the rest might be.
In the long run you might save a lot of money by installing prefab units, as there are some nice options out there now that were not available just a few years ago.

 

[Jadnashua]

In residential, the common build is for a 50# load/sqft divided between dead and live (always have trouble remembering the ratio, sorry). Two layers of tile and an underlayment probably have already eaten up the dead load for the design unless you're dealing with slabs where it doesn't really matter anywhere near as much. I don't know what your place was built to...commercial may use a different design load, or even in a residence, it could have been built stronger. Wooden structures have both a spring action and a flow action. Long term loads can actually cause the wood to flow. You can see that sort of thing on the ridge of old barns, or a suspended bookshelf. Short term, it will bend then spring back...long term, it sags and won't, developing a permanent bend. Since you can't flip the structure over like you might be able to do with a bookshelf...it becomes permanent.

If you find out it is capable of the increased load, one of the paint on primers like Mapei's EcoGrip Pro after you've cleaned the floor really well should give you an adequate bond for that new layer.