Can I lay tiles straight over existing tiles?

The simple answer is 'yes'. The floor underneath needs to be solid and there can't be any cracks in the existing tile. Here are more details:

https://www.bobvila.com/articles/can-you-tile-over-tile/

You will need to make sure all grout lines are level with the tile and no cracks. I wouldn’t recommend it because it’s a lot of prep work plus the floor will be extremely heavy.

It would always be better to remove the existing tiles before adding new to eliminate any future issues that may occur.

Hi Brodie, it's not a good idea to lay tiles over existing tiles. I would suggest removing the old ones first or if that sounds like to much work, perhaps you can consider painting your tiles instead. Here's a great tutorial that will show you how - https://www.curbly.com/paint-tile-floor

I agree with everyone else. I would remove the previous layer of tiles. I am assuming it is ceramic tile. If it is a vinyl tiled floor that is very flat as a first layer, then sure, putting ceramic tiles over that would probably be fine. But ceramic or porcelain tile over ceramic tiling would not be ideal.

It depends upon the tile and how secure and flat the underneath tile is.

If the previous tile floor is in excellent condition and adding additional height to the floor is not a problem then pouring a floor leveling compound over the existing tile will give you a flat base to put new tile over. HOWEVER, it will never be QUITE as good a foundation compared to ripping out the old tile and starting over. But you can absolutely do it.

You can lay large format tile over small format tile.

https://todayshomeowner.com/video/how-to-lay-tile-over-a-tile-floor/

Yes as long as they aren't damagaed.

Hello Brodie,

Yes you can but, make sure the joints don't line up - use bugg or smaller tiles. good luck!

Yes, you can do this, here is a step by step guide with some helpful information:

https://homeguides.sfgate.com/install-new-ceramic-floor-tile-top-old-ceramic-tile-21370.html

It is not recommend on a wooden floorboards.

Are you wanting to lay new tiles over existing tiles on a shower floor, or on the floor of the room?

as long as flooring under is solid as well as grout and you have the clearance for new layer on floor as it will matter around door jambs and baseboards, cupboard areas. Also need to consider additional weight on floors with all added tile; slab ok not so much second story area or wood flooring; is flooring under first set of tile in good condition? can it hold all materials

You can. You should NOT.