The answer to this question is really neither. The top board of my railing is 5/4 deck boards. And I think it will be your best option given your small deck. from the Ohhio Turnpike. I want to build a low profile deck at the back of my house but I don't have enough room from the door sill to the ground to use 2X6 joists. Some folks use 2x6 on 20 to 24 inches centers but I … Discussion Starter • #1 • Aug 28, 2013. I just finished mine and went with treated 2x6's. I got a house that is built in the 1950 is has a roof made of 2X4s a few of the rafters are split I want to turn it into a rigs and valley roof, //