Applying your decking horizontally is usually the easiest method for finishing a deck’s floor surface.  Before you get started you will need to install sway bracing to protect the deck from racking.  You can then proceed to lay your deck boards parallel to the house over the joists.  Deck boards should be fastened at every joist by 2 nails, 2 screws, or some kind of hidden fastener system.  Make sure your fasteners are the correct size and compatible with new pressure treated lumber.  I

f your deck is less than 20’ wide you should be able to finish the deck without any butt joints or splices.  However if your deck runs longer you will want to splice the deck boards over a joist.  You may want to stagger the butt joints as best you can in different positions to reduce their visibility or use a division board to control or concentrate them in one logical location.  Wood deck boards are usually available in 2’ increments while most composite decking materials are limited to 12’,16’,20’.  Depending on the width of your deck this could result in a large amount of wasted material.  Plan for efficiency and you save yourself some money at the end of the project.