Measure the room, find your center, glue up and install. So lightweight and simple. Practically seemless but I used painters caulking  on the joints..oh and remember you need to add a molding with these if you have to cut the for end pieces...I failed to do that when I added 3 end pieces and realized it wasn’t right. Trying to make a smooth cut and removing after glued up was a nightmare. Hey lesson learned...I love how these tiles look and it covers the old horsehair plaster ceiling beautifully. I highly suggest this product. This 10x12 room, tile, foam molding, corner blocks, caulking and glue under  200.00..so worth it..need to prime before you paint.