zip walls and hardi board

Anyone know the technical details for installing hardi board or any cementious siding over Zip walls? The Zip walls eliminate the need for housewrap when many types of siding are installed but what if the hardi board siding has no caulk or flashing at the butt end joints? Seems like moisture will stay between the siding and Zip walls…

Hardi plank siding requires flashing at the butt joints. Usually trim coil of a matching color is used but I believe 30# roofing felt is also allowed. The joints should never be caulked. When I am back to the office I will post the installation instructions that provides detail drawings. They are also available on the James Hardie website.


I would think it should be installed over a ZIP wall same as it would over one with house wrap. They each provide a water “resistive” barrier, Not a water “proof” barrier.

• Joint flashing behind field butt joints is
required for ColorPlus and recommended
for primed products.

DO NOT Caulk field butt joints on
ColorPlus siding.*

• It is OK to Caulk field butt joints on
James Hardie primed** siding products
that is to be field painted.

• DO caulk where HardiePlank meets
vertical trim.

Hardi Plank requires installation to their specifications, what its installed on makes little difference.

I agree, the Zip walls are an awesome product but it looks like some builders will assume they can make other shortcuts when they use the zip system.

I had reps from Hardie Plank fly to Phoenix to look at their product installed on 100’s of shaqs in a subdivision, the builders sub had to rip the siding off every shaq and start over or no warranty from James Hardie Corp.

Believe it or not, Bruce, some shaqs they tore the siding off a second time before getting it right.

Some of the homes had the upgraded zip wall system, after they tore all the siding off there was little value for the zip walls with more holes than swiss cheese from nail guns.

Its really incredible how easy it is for these nitwits to pre-destroy a shaq before its even finished.

Its really incredible how easy it is for these nitwits to pre-destroy a shaq before its even finished.

over and over again