sO, i HAD THIS DECK BUILT

[Maggot]

Do your chair legs ever fall into the cracks between the boards on your deck?

This reply thing mat be screwing up but yeah I built her deck I didn't use a home depot diagram and just know that as the years go by the gap tends to open. I always butt the floor boards up close because they always spread. If you give them a half inch gap they end up being an inch after they dry. But yours looks OK. It should have preservative painted on it every year and that's what I do to mine. I just use a clear coat with none of that stain in it. I also just use a big 4" brush and slap it on not caring about anything but just covering as much as I can. Yours looks like it would take a gallon as its very thin. Hose it off, let it dry, then slap the preservative on. 
Nope. Not much of a gap between the board of the floor.  Barely a half inch or so.  The guys who designed it and built it were friends of Mr. Bee.  They built us a ramp on the front of the house, too.  The one who "designed it based on what I wanted, took his measurments and drawings to Home Depot and had them do a 3-D printout of it.  That determined how much lumber to buy.
Maggot, if memory serves, you do stuff like this, don't you.  I seem to remember you helping out LC (RIP) with something, but do not remember what.