Agree!!! Yet another of 1000 uses spray foam should not be used for!

 

There is close cell and open cell foam. Also our 2010 to 2014 f150s all have foam from the factory in between the double wall of the rear fenders. That's why the rust eventually but it take 7 to 9 years to even show up on a xl/XLT on higher trims the rust is behind the factory flare, you just can't see it unless you remove the fender flare. It buys another 5 plus years at least.
You guys don't even want to know what was done to "sandy" vehicles. They are still popping up.

 

Open or closed foam will make little difference. Both will still trap moisture. If filling your rockers with closed cell foam made a difference companies like Ziebart would be doing it.