To make the space under my deck more usable when it rains, I've installed rubber screen spline between the seams on my composite deck and also installed gutters at the low ends to channel rain water away...The deck is built with a small slope, away from where it attaches to the main building...I can see that rain water does flow down the 'sealed' seams and into the gutters.
This has reduced the amount of water that flows between the deck seams to the lower 'porch' area by 98%...but there are still some areas where water will penetrate through the seams (small drips) instead of being directed away.
So I'd like to know what type of additional sealer (see picture below) - either a paint or a self-leveling fluid caulk I could apply into the seams (on top of the spline) to eliminate the small leaks that still occur in places where there are very small gaps between the deck boards and spline.
(Note - the screen spline was rolled into each seam and it sits about 1/4 inch below the deck surface. The seams are about 1/8 inch wide. Each deck board is one piece, 7/8" x 6" x 11 foot) Ideally I'd like to apply some kind of sealer that is about as viscus as water so it would flow down the slope of the seams and into the small gaps that are currently allowing rain water drips...
I'm thinking a thinned house paint or a semi-harding, enameled deck sealer might do the job - - setting up somewhat flexible to allow for expansion and contraction...I understand that I would probably need to redo this every couple years...I really don't want to use regular caulk if I can avoid it.