Should Decking Boards Be Horizontal or Vertical?

Running the boards parallel to the length is always desirable, it gives the deck a much bigger look. If you run the boards parallel to the width, it tends to give the deck a stumpy look, not very desirable.

Does it matter which way you lay decking boards?

A board that is correctly installed right side up (or bark side down) will form a crown and allow water to run off the edges. If the board is installed wrong side up (or bark side up) it will curve up on the edges when dry and water can gather and sit in the cup. That is a recipe for wood rot and problems.

Should deck boards go parallel or perpendicular to house?

Some decks are designed with a joist orientation parallel to the house. This is useful in cases where you do not want to hang framing members from the house wall. In order to rotate the joist's typical direction, you will need to install beams that project perpendicularly out from the house.