This is a common question that I get a lot and there is some debate on which is better to install first the floor tile or the wall tile when you are installing a shower surround made of Tile.
The first thing that you have to consider is that in all other places in your home when you are installing materials where water is a problem you want to start at the bottom and then overlap the top pieces so that water mechanically sheds because of the material. So then why is there this big to do about shower tile? I don’t know.
When you are installing shingles on your roof sure you can start at the top and go down then cover the whole thing with tar and caulk… no wait you can’t do that.. you start at the bottom edge of the roof and work your way up to the peak to allow water to mechanically shed off of the shingles. The same is true when you are putting siding on your home or installing flashing around a fireplace that extends through your roof. You always start at the bottom and then the pieces that are higher up will allow the water to flow naturally over the bottom pieces and out the shower drain or down the downspout from your gutters.
Then people say but there is grout and the shower pan.. sure there is but the same is true about flashing or shingles that have asphalt sealers. The caulk, sealers or in this case the grout is there as a backup to the tile not as the primary method. Grout will eventually fail as will all caulks and sealers but when the physical part is installed correctly the failure of the caulk or grout is minimized.
Now nothing is perfect in this world and grout and shower pans will fail and tile will crack and pipes will burst but the debate about this subject really makes me wonder where these people are coming from. Most of them are hobbyists and not professionals.
A professional that is putting in your shower pan will normally use the mortar bed material to adhere the tile to the pan and not even come back with a second coat of mastic to lay the tile. They just don’t have the time. Normally the floor tile is set when the mortar bed goes in and if they are a good profesional they will use a porcelain floor tile for the floors and maybe a glazed ceramic which is not as tough for the walls. However that depends on the customer because they might want stone or any other material. But Porcelain Tile sets perfectly into a mud bed in one step and that saves money and time for the contractor.
Like I always say follow manufacturer’s recommendations on how you should use their products but in this case you should also use some common sense.
Do you really want to be butting your floor tile up against soft wall tile? or is it better to do what is done with every other material in your home and work from the floor up? For me the answer is simple because you are allowing the wall tile to stick out and over the floor tile to shed the water into the drain.