I would prime hardie board siding with Loxon primer or their multi-purpose primer from SW. Which ever is on sale
If it is red siding use a grey primer first. Have them tint it to P-2. They will know what that means. That is a very light primer and will kill the red. If you use white primer it is harder to cover. Then I coat with Duration satin exterior. This is what Hardee puts on their pre-painted siding and what they spec. I also use vulkem caulk. Do it this way and you will have a pro job that lasts years.
