# Hardiboard and Elasometric Paint



## traderfjp (Feb 8, 2019)

I have a house with new hardboard panels. It's been up for while and has a good vapor barrier. I want to prime with a good masonry primer and then roll on two coats of Behrs elasometric paint? Is there any reason I shouldn't use this paint. The previous owners used urethane caulking where the seams meet which looks solid. Hoping the thicker paint will hide the shadow lines where it's caulked. Thanks


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## Epoxy Pro (Oct 7, 2012)

traderfjp said:


> I have a house with new hardboard panels. It's been up for while and has a good vapor barrier. I want to prime with a good masonry primer and then roll on two coats of Behrs elasometric paint? Is there any reason I shouldn't use this paint. The previous owners used urethane caulking where the seams meet which looks solid. Hoping the thicker paint will hide the shadow lines where it's caulked. Thanks


You need to find out what vapor barrier material was used and check with that MFG. Some vapor barrier materials can not be top coated.


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## traderfjp (Feb 8, 2019)

Epoxy Pro said:


> You need to find out what vapor barrier material was used and check with that MFG. Some vapor barrier materials can not be top coated.


Hardiboard material is being topcoated not the vapor barrier. The vapor barrier is under the Hardipanels. As it should, I just never used Elastrometric paint. I guess I will test it out and see. We get a lot of really wet weather where I am so it would be good to have a water tight seal on the entire house.


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## kmp (Jan 30, 2011)

While elastomeric paints can be used on substrates other than concrete and stucco it is not really meant for it. Elastomerics do not breath like regular paint and if water gets behind it the stuff can come off in sheets. The extra mill thickness needed for it to work when rolled on plank siding will have lot's of stipple and brush marks.


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## SemiproJohn (Jul 29, 2013)

kmp said:


> While elastomeric paints can be used on substrates other than concrete and stucco it is not really meant for it. Elastomerics do not breath like regular paint and if water gets behind it the stuff can come off in sheets. The extra mill thickness needed for it to work when rolled on plank siding will have lot's of stipple and brush marks.



Not to mention the spread rate per gallon of elastomeric paint is low, typically less than half that of a good acrylic/latex.


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## woodcoyote (Dec 30, 2012)

Do yourself a favor and pick a good / high quality 100% acrylic exterior paint. Not an elastomeric. 



The elasto has too much body and won't level our nicely, there's a good chance it won't give you a good finished look. Plus depending on your color, it will fade at a much faster rate.


My choice: Duration Exterior or Super Paint Exterior.


Good luck.


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## rufus mcgillicuddy (Apr 14, 2009)

even on florida high rises they are using more latex house paint than elastomeric. if a quality latex exterior house paint did not "waterproof" wouldn't painted wood rot? most paint companies offer the elastomeric but sell their top quality latex. we have a hardiboard job painted 12 years ago with bm ultraspec and only the windows (wood) needed attention 2 years ago.


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## PNW Painter (Sep 5, 2013)

Don’t worry about trying to hide the caulk shadow lines. You’ll only create more issues if you try and bury them with paint.

Everyone that I know in my market uses Acrylic exterior paints for Hardie. I’ve personally had excellent results with SW Duration and BM Regal Select High Build on new Hardie. I’m spraying 2 coats and I’m not priming it.

If the Hardie has been sitting for 6 months or more you should prime it. SW’s Loxon primer would be a good choice. 


Sent from my iPhone using Tapatalk


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## ridesarize (Jun 19, 2012)

Traderfjp I wouldn't use elastomeric, and I would REALLY skip the Behr paint. Get Miller Paint, kelly-moore, benjamin moore, sw, any real paint store product.... There's no need for that kind of flexibility (elastomeric) with that type of siding. 



If the previous owner caulked it with elastomeric caulking or Big Stretch caulking, then perhaps elastomeric paint would be beneficial. It is overkill other than that issue.


Be careful of bridging the lap siding together. You want those laps to be able to breathe air. That's why pros spray lap siding usually.


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## diT (Jul 24, 2019)

Elastomeric will look terrible on new Hardie and is completely unnecessary.
I paint apartment building exteriors and we use Superpaint or Kelly Moore with no issues.
It's not necessary to use a masonry primer either.
I've put thousands of gallons over new Hardie the last 20 years with no problems.
As said above, elastomeric will trap moisture and fade relatively quickly.
Two medium coats sprayed will cover and give you an adequate sheen build.


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