ARK Survival evolved - Help with bridge-building

I´m trying to build my first bridge over a river. I´ve read a few guides and understand the basics with ceilings and using pillars when the game demands foundation. I was also gonna try the trick with a bridge at ground/water level and see if I can skip the long pillars to the upper bridge.

However after two pillars out I´m not allowed to place a new ceiling at the upper bridge, directly after the pillar because it demands a foundation. The pillar goes all the way down to the bottom of the river. I´ve tried both with and without a foundation at the bottom. Any suggestions? As it is on the pictures I can´t place a single more ceiling piece.

http://images.akamai.steamusercontent.com/ugc/270595545393317600/75372443ECCB9E65DBE120B1B2631B70F82DE0FD/

http://images.akamai.steamusercontent.com/ugc/270595545393317407/911DACD5D9481172F8B3EBE09E22625DFD735495/

Edit: I solved it for now. I was gonna demolish the last pillar which proved extremely difficult as a solo player. I built from an Argentavis but trying to demolish off course just sent me flying off.

So I tried placing a ladder on the pillar but it wouldn´t snap. On a whim I placed a foundation next to the pillar and then it snapped. What also happened was the pillar now counted as grounded so I could place new ceilings on the upper bridge. And the lowbridge-trick also works, as you can see I have now extended four ceilings on the upper bridge.

No idea why that foundation to the side did the trick but hey, I´m not complaining.

http://images.akamai.steamusercontent.com/ugc/270595545393583714/F224E04F99B9108FBF73CA48B9D23396AD0F8BE2/

http://images.akamai.steamusercontent.com/ugc/270595545393583502/66FFEF9E70BC3732FC536E8F17470A2C2F3A8BD8/