Runtime manipulation of terrain

I plan on making a 3D tower defense game.

I’d just like to know how I should deal with building placement.

For example if I have a building that goes into the ground, like a trench, there has to be some new space.
Or otherwise if I have a larger building and I want to place it on uneven terrain, how could I even out the ground.

Is this easily achievable?
Would I need to use voxels? (and therefore 3rd party plugins, which I wouldn’t really want)
Is there a way to do this with landscapes?
Or should I use meshes in any way?

Thanks in advance!

What’s more:

At this point I don’t actually care if I somehow cheated so it only looks like the trench goes into the ground without it actually manipulating it.

What I don’t want is to have it surrounded by dirt so it’s more like a dam rather than an actual trench…

Actual run-time terrain manipulation is not supported by default in the engine. There are workarounds, but they are a bit complicated.
If it is only about leveling out terrain for the building, i suggest you looking at blending meshes with landscapes and using some sort of foundation, seamlessly blended with landscape.

This looks nice, but I don’t think I can apply it here…

I might look into it if I don’t find anything else…

However, as I said, I’d prefer using default Engine features only, I don’t really like using 3rd party stuff, mainly for compatibilty and licensing reasons.

Thanks for answering though!

Another idea, maybe, though I think it’s not that easy either:
Can you maybe change the visibility of certain parts of a landscape?