I have a 4' by 8' closet wall that I am replacing. My father in-law tells me that I need to install the sheet rock horizontally, cutting the 4'x8' sheet into two 4'x4' pieces then taping and mudding the seam. I think it would be easier to put it up vertically in one piece no seam to mud. Is there some structural need for Sheetrock to be horizontal?