Import site model in Sketchup

I imported a site model in sketchup, however they are all on different heights (+1m or +0.5m etc,) Is there an easy way to allign every mass/volume to the same height??

Thank you

With Fredo6 FredoScale or with Vertex Tools

Thank you for your answer.

Is this also possible with the buildings on the site? They are no groups or blocks, just lines and faces.

Do you want to align each building with the bottom at the same level?
If you group them each one, then you can align them that way

Yes I want indeed all buildings to be alligned to the same level.
Which tool do you use here? How can I get this one?

With CLF Loose to Groups make groups from your raw geometry (separate buildings/groups) and with Curic Align align groups.