how do i do the measuring and lay out on a 10 foot by 6 foot floor when laying the tiles diagonally?
A 10x6 room requires 60 square feet of tile to cover the floor. On a normal square to the walls pattern, I would order 10% more tile to cover waste. On a diagonal pattern, you will have more waste. I would order 15% to 20% more tile to cover waste. To set up to lay the tile, I start by picking the most obvious sight line in the room - maybe from the next room through the door and chalk a line perpendicular to the far wall along that sight line and parallel to the side wall. Then you chalk a line 45 degrees wall to wall through the center point of the center of the first line. This is your 45 degree pattern. Chalking a line wall to wall 90 degrees from the second chalk line through that same center point gives you your grid pattern to set your tile from. Ignore the first line - that was for reference only - line two and three are the lines you set your tile from. Set out tile dry with spacers to see if you like the effect. I will sometimes set out all of the whole tile possible in the room and walk around to see if it looks good. If it doesn't look right or you end up with too small pieces along the edges or in the doorways, you can move your initial start point and rechalk your lines.
Find the largest open square in your floor. Strike a cross from corner to corner of this square to get a center point. You can lay out some tiles based on this center point to see how it ends up running toward the door opening (also a significant sight line) and the walls. You don't want slivers of tile cuts at the walls or door opening so you want to manage the center point around these areas. Allowing for larger grout joints can help you with this issue as well though larger grout joints just make for more sanitary issues in a bath floor.
