I know this post has been ripening a while, but I just saw it - all quality house painters recommend brushing on paint - forces it into the crevices and protects better. Hope this reached you in time

I'm in the same boat. Just finished putting on about 250 pieces of Hardiplank on a new home we are building. Originally I planned on renting a sprayer and trying my hand at spraying as much as I could.

The more I research, the less this looks likely. Still wondering if it is a possibility, or a definite NO. (?)

Would the paint have to be thinned to the point you are compromising it? Planning on using SW Duration paint.

Further, my carpenter-in-crime says he thinks I should caulk each plank on the bottom, or its not going to look right once its painted. Oh lord.

There is a technique that actually incorporates both spraying and brushing, assuming you are using an airless paint sprayer (type without air compressor), and no thinning necessary.

With this process the sprayer applies the paint to the siding and the brush or roller is used to lay the paint down evenly allowing it to penetrate the cracks, etc. This is called spraying and back brushing or, if using a roller, spraying and back rolling.

This can be very efficient and works best with two people if possible. The sprayer applies the paint to the siding in a manner allowing the brush or roller to follow behind laying the paint out. It is very quick and leaves a nice even finish.

Most cracks should be caulked before painting. Some will last and some will simply crack back open.

>>I know this post has been ripening a while, but I just saw it - all quality house painters recommend brushing on paint - forces it into the crevices and protects better. Hope this reached you in time This is generally true for wood because wood is very porous. You want deeper penetration of the paint into the wood for greater protection. The fiber cement siding is a different animal entirely though because it is not as porous, so I think spraying would be fine. You always want to read the instructions that came with your siding for application instructions or if it is a James Hardie product you can visit their website for paint application instructions.

>>I'm in the same boat. Just finished putting on about 250 pieces of Hardiplank on a new home we are building. Originally I planned on renting a sprayer and trying my hand at spraying as much as I could.
The more I research, the less this looks likely. Still wondering if it is a possibility, or a definite NO. (?)

Would the paint have to be thinned to the point you are compromising it? Planning on using SW Duration paint.

Further, my carpenter-in-crime says he thinks I should caulk each plank on the bottom, or its not going to look right once its painted. Oh lord.Does your carpenter friend know anything about building and construction? Moisture needs to get out from behind the siding and it escapes through the gaps under each lap of siding. This is also the reason that you see tiny weep holes on the bottom of every piece of aluminum or vinyl siding. Caulking under each piece of siding will result in massive paint failure. When painting any type of siding, I always try to even minimize the amount of paint I put under each board so that I do not plug up those gaps with paint.

I have never sprayed Duration, but if you have a good airless you should not really have to thin any paints if you run them through a good sprayer. Read the can of Duration for recommendations in regards to spraying.

These are some good tips. My main problem is I'll likely have to handle all the painting alone, that's the nature of this project.

As for if my friend knows anything about consruction--just had to respond that he's been building/remodeling houses for 32 years and is the finest, most capable carpenter I've ever known.
BUT, this is his first real experience with fiber cement, which is still not very prevalent here in small town Oklahoma. The caulking comment was just an offhand remark one day when we were talking about painting over the Hardieplank's funny yellow primer.
I'll definitely look at James Hardie's website. Whatever instructions came with the siding are gone with the wind.

"Caulking under each piece of siding will result in massive paint failure."

In a wet/humid environment, it can also lead to failure of the underlayment which will lead to rot and mold issues in the wall cavaties.

We are in the process of getting estimates for painting our home. It has been painted one time by the builder. I believe the siding is Masonite. There is a $300 or less than 10% difference between the spray and the roll and brush estimate. The spray estimate states he puts the paint on as heavy as if it were rolled. We are willing to pay more if the paint job will look better and last longer. Any suggestions?

Yes, no caulking the siding. The best is to have a drainage plane behind the siding.