Animation of a cliping plane

Hi,

we have modelled 3D-Building and would like to animate this building by a clip plane. The result should look like as the Building slowly raises (building up) in time.

I have tried to keyframe the clipping plane in the z-direction, but with no success. I might miss something here or maybe there are other ways to do that.

Help is much appreciated, thanks.

Cheers,

Felix