Barriers, Permissible and Penalised.

Barriers are by definition a device for limitation. Kinetic, elemental, living... I think you get where I'm going. There are however limitations on the limitations if one so desires. This would involve creating harmonic changes in the latices or making the matrix itself permissible
Think of an elemental matrix. With heavy strands of water and thin strands of air set up in a barrier configuration. The two elements would be difficult to weave together under normal circumstances though it is possible just requiring more attention and energy to maintain (Which brings up the whole "locking" of spells myth, which we'll discuss another time).
Now if somebody, lets say a stupid orc was to try and move through this barrier then there is a good chance the stupid orc would become doused in hot scalding water. But if we reversed the thread ahem, "weights" then said stupid orc would while walking through the barrier become encased in ice.
In the first instance we saw the weaves provide a penalising limiting barrier. And in the second instance a more limiting and effectual barrier to motion. Of coarse the orc is not renowned for intellect so after he defrosts he tries again. This time however, we'll pulse the air strands in the barrier. Now when stupid orc attempts to pass through the barrier, we see an instant effect in that he appears to be moving through a blizzard. And the stronger we pulse the air strands the harder it is to move through. Now an orc is stupid, there is no denying that. But an orc is a creature of the cold by its nature, so we probably will not kill it with the strong air strands, however if we reverse the entire polarity of the matrix. Making water strands strong and pulsing. The orc will die because boiling hot steam as a strong head wind would inevitably kill the half wit orc.

As you can see, a permissible barrier is possible. It just requires a bit of know how and creative thinking.