Maybe read New Square Foot Gardening. Suggest using two 8' boards and cutting them in half to yield, 4 pcs 48" long, No need to pay for 10' long boards. Using four pcs at 48" long produces a raised bed that is 46 1/2" square. This is fine for Square Foot Gardening Techniques. If using damp lumber, suggest assembly quickly. Damp lumber will warp and twist, making assy more difficult. Suggest making corner post 18" tall above bed. I use these tall corner posts to aid getting up from kneeling position. I'm older and wiser.