MagicManICT wrote: all adjacent squares
AFAIK it only breaks pieces that it is "connected" to, not lets say another wall beside it.
To answer the question: if you're building the brickwall and palisade directly beside eachother, make sure the brickwall is on the outside. What can happen later on in the world is people would be able to handbreak the palisade, and then shelter a ram with it to then penetrate the wall