Is it posible to create a transaction output that can either be reddemed by privK of Addr A or by privK of Addr B AFTER certain blockheight? I am thinking about how to secure your Bitcoin savings. 

One idea I had was to create sort of a "backup" address B for an address A which stores the bitcoins. So what I want to achieve is that you are able to spend your bitcoins with the private key of A at any time. But in case you lose access to the private key of A you are also able to spend the bitcoins with the private key of B but only after a certain amount of time (i.e. blocks) has passed.

Would something like that be possible with the Bitcoin scripting language? And if so, how would one achieve this?

Thanks in advance.
Certainly. You can do this with OP_CHECKSEQUENCEVERIFY which allows for relative timelocks.

The basic structure would look something like this:

IF
    &lt;pubkey A&gt;
ELSE
    "30d" CHECKSEQUENCEVERIFY DROP
    &lt;pubkey B&gt;
ENDIF
CHECKSIG


Read BIP 112 for more information.