The main reason of this answer is to combat the erroneous views as to why the brick texture is distorted.

The mortar attribute is a constant set by the Mortar Size option, not a percentage.



This issue is caused by scaling the mesh that the texture is applied to. Applying the scale will not change anything, as the generated UV's for the brick texture still remain the same. You need to UV unwrap your mesh properly and use that to drive the brick texture UV coordinates.

A default plane will give this result:


While a scaled one will give this result:


Again, applying scale does nothing. I tried it, several times. Instead, UV unwrap the mesh and set up your nodes like this (or try @chebhou's suggestion):



Now you can change the UV unwrapping and the mortar will change in width as well. You may need to change the size of your bricks once you have the mortar size correct.

Can I set the Brick Texture Node horizontal mortar size to be equivalent to the vertical mortar size?
I have a HP DV7 with an ATI graphic card and I have a Samsung monitor connected to the laptop. Every time I turn on the laptop the displays are mirrored and I have to go to the Catalyst control centre (Administrative) and change the displays configuration, I have to do this EVERY TIME I turn on the computer.



I Didn’t try the solution suggested here ( Settings for multiple monitors are not stored ) because it took me a lot to make the graphics card work properly and I want to make sure that I have the right solution ( or the "rightest")  

Thanks!
