Can I put a heavy flower pot on my terrace?

Hello.

My apartment includes a rooftop terrace. I want to put a big planter there 80x80x50cm. I made it out of europallets - let's guesstimate the weight of that to be about 75kg. About 320 liters of potting soil will fit there. The potting soil I bought has density of about 15kg per bag of 40 liters, so effectively my planter fits 120kg, together it all weighs about 200kg. I want to plant a small tree, but I don't think that the weight of the tree itself makes a difference here.

The problem is, what if it's rainy season and the soil gets very wet. I don't know how to correctly approximate that. Obviously, upper bound is that it cannot absorb more water than there would fit in an empty container. So like 320kg.

The conclusion is, all of this is going to weigh somewhere between 200 and 500kg. Probably realistically around 300kg, but 500kg is good upper bound guesstimate.

I've reached out to the building administration about maximum floor load and I gave them a photo and measurements of the planter - they said that the floor load is 150kg per square meter and the planter "shouldn't be a problem". On the pics it's just a relatively small wooden construction so it looks light but I don't think the guy understands just how heavy soil can get.

I feel I'm in the clear because I asked, but at the same time the guy didn't actually read into my question, so he's not really taking the responsibility.

I've been talking to ChatGPT and it keeps giving me conflicting answers all the time. There are two ways of thinking that seem logical to me:

1. If it's 150kg per square meter, then I should build a giant base so that the load is distributed, because that worst-case 500kg on a 80x80cm base will result in a huge concentrated load.

2. The floor itself does some weigh distribution so it's not going to be a problem as long as I don't put anything heavy around the planter. So if there's nothing within 1m radius of the center of the planter, then it evens out and it's fine.

What do you think about this?