Very heavy bathroom tiles

[Midlifelady]

I am buying an Edwardian end of terrace house and the bathrooms (currently carpeted) need redoing. I've ordered samples and the one I like best are coloured cement- very thick and heavy. They are floor tiles but I'm wondering about the added weight, particularly in the loft? It was converted before the current owner bought it, so though there is a bathroom there I do not know if the joists were reinforced.
My question is, are floors strong enough to support the weight of these tiles (not just the loft, the first floor bathrooms too), or will I need to reinforce them? The weight of these tiles is something - twice a normal tile I'd say. I guess I'll could take the floorboards up to check...but what have others experienced?

A floor that has been built for use as a floor will be fine. You would put a heavy wardrobe on a floor without worrying, wouldn't you?

Loft joists..... depends on whether they were reinforced for use as a floor.

How much do you think a bathful of water weighs OP?

There are a number of things to think about here. Area of the floor and supporting structure are important but probably more so is how stable is the floor? Tiling on timber floors is always prone to problems, commonly the floor is covered in ply first to try to reduce movement, this adds weight and height. Excess movement will lead to the tiles cracking or lifting. By far the worst problem is accessing services under the floor, typically the tiles have to come up and usually bits best to tear out the whole floor and start again. I've got a section of floor in my kitchen that is tiled over joists, I've got two layers of 19mm ply and 5" joists payed up almost their full length, it hasn't cracked so far... but it will eventually! My preference is lino or lvt in an upstairs bathroom - though I do like tile it just seems too much of a gamble.

Thank you.
@ReceptacleForTheRespectable fair point!
@SaucySarah, yes but there already is a bath there and this will be added weight, hence my worry.
@omygoditsearly I see your reasoning, but I imagine it's all wood supports. I have vinyl in my current home and never again - the dirt that just seems to stick to it!

We had full floor to ceiling marble in an old bathroom with no problems.