It is just a question of breaking the joints on every other sheet. For example, startwith a half sheet and then use a full sheet for every ne after. In the next course start with a full sheet and again use full sheets thereafter. This will break the end joints of the sheets staggering the joints. If this leaves you with a small piece at the end of the floor then you may need to lay out the sheet pattern so that you start with more or less than a half sheet and the first and last pieces are the same size. Confusing it sounds but not so in practice. Good luck...Mark Hammond
Alternatively, measure the room to determine how many boards you will need to run the entire length. Usually, you will need to cut a board at the end in order to have a perfect fit. For example, assuming you are using 5 foot long boards, and your room is 18 feet wide, you would use three full boards (15 feet) and cut one board to 3 feet. Start the first run with a full five foot board, then the next run with a 3 foot board, then the next run with a 5 foot board, etc. Doing so will sufficiently stagger the seams into a grid. 5-5-5-3, then 3-5-5-5, then 5-5-5-3, etc.
The purpose is to prevent any slight, subtle twist in the floor from settling from showing up as one long huge crack in the floor. It is important if your subfloor is plywood, which will twist easily. You want to stagger the seams of the cement board so as to create a stronger, more unified subfloor. If you are laying it down on a concrete subfloor, then it is not so crucial that you do it.
[This message has been edited by Lawrence (edited June 16, 2002).]