I am planning to take down a wall and also replace a window with a sliding door. I founds some good information about headers and i would need 2 x (2x12") headers to support it about 6' entrance. I'm thinking use 12x12" solid piece so it will be viable. Then another 2 x 12x12 x8' pillars supporting the sides. Steel footers in the basement. Is a 12x12" Piece stronger that 2x12's ? I guess it has to be against the grain would be important? I guess 8"x8" would be enough too?