Is drainage necessary under the entrance platform?

Hello everyone,

we want to cover the entrance platform of our single-family house with natural stone.
Basically, it is just one step, about 2.40 x 1.20m in size.
As material, I have chosen 60x60cm flamed basalt slabs.

The platform was already poured from screed months ago. It is sloped forward, that is, away from the house, so that rainwater can drain off.

The question now is, do I still need a drainage for this?
The tiler says no, a friend who is a civil engineer says yes.
If the slabs are properly glued, how could the slabs then freeze? What would a drainage even achieve? Water would never penetrate that deep.

Many greetings

If there is a risk that water can get through the joints between the panels and the screed, these can already cause damage during frost. In the worst case, the panels could come loose.

If there is a risk that water can get through the joints between the panels and the screed, this can already cause damage in case of frost. In the worst case, the panels could come loose.

But if water should get through the joints, then something is wrong with the joint.

Why, joints are not necessarily watertight - and how do you want to notice? If it's too late, then it's too late - so seal well beforehand or provide drainage.

Can’t the plan backfire if you want to deliberately drain water through the drainage but maybe can’t drain it because the ground is frozen and then frost comes again? Then everything would freeze completely, wouldn’t it?

Yep, there are heated drain channels for that.

I prefer covered solutions, then you have (hardly) any problems.