To Caulk or Not to Caulk under Hardiplank?

[Stephen Hundley]

I've heard differing opinions on whether or not to caulk under Hardiplank.  I've heard a painter say not to do it bc it's only a cosmetic thing and doesn't actually prevent water from getting behind the boards.  It also costs a lot of time and money for a painter to caulk the whole house.  

Is it risky not to caulk below all the boards?  Anyone have experience on this subject.  

For a little background on this project...My goal is to build this as cheap as possible bc it will end up being a buy and hold investment property after I live in it for about 3 years.