I have seen the Hardibacker siding which looks like conventional siding but I want to know just simple flat hung hardibacker used as exterior siding is acceptable.  Aside from looking "cheap" I question that you just hang it like drywall as an exterior finish especially in a climate like the Northwest.  Do you have to do anything special? Treat, etc or will that last as is?

Hardibacker is not rated for outdoor use - at least not as a tile backer. I believe the issue is freeze/thaw damage - which may not be a problem in your climate. My concern with fiber cement siding is permeability - the raw material soaks up water like a sponge. You would want to be careful about sealing (proper painting) the surface and edges.

A building scientist from the NW told me that he has seen instances where the bottom edge of fiber cement lap siding was not well painted - water soaked in - and when the sun hit the surface vapor drive pushed it in to the sheathing. The result - rot.  If I were installing fiber cement in your climate I'd being doing it as part of a rain screen system.

Dave

Dave,

The Sept. 2008 Fine Homebuilding has an interesting article on "factory-finished siding:  a paint job with a 25-year warranty."  The author suggests that its available as a service through the siding vendor and can be either stock or custom colors.  That then leaves the cut ends to prime and paint -- but they're out of the sun.

Larry

Larry,
You are correct about the pre-finished fiber-cement siding - and the need to follow the mfg's installation instructions by sealing cut ends. GreenGoddess was asking about HardiBacker - a tile backer board that is not normally used as siding and does not come painted or primed.

Dave

I know about the pre finished siding.. this is not that.. it seems to be well hardibacker used as siding.. I could be wrong but I can't find anywhere or info about that... it just seems "wrong" and in the NW to use that without even a paint.. I just have a bad feeling about this choice.

Greengoddess - is this detail (raw HardiBacker as siding) something you plan to do - or something you have seen others doing? It's a bad idea - not because the fiber cement will deteriorate but because moisture will get behind it and rot the sheathing and framing. We're not talking about leaks at the seams - but moisture passing directly through the material because it's porous.

There are fiber cement siding materials that comes in 4x8 sheets - but even that would have to be painted - not to protect it but to protect what's behind it.

 

 

Ooops. 
Not even a close but no cigar.

Larry

I have used hb on my cottage near the water in Connecticut. I used it as a skirt at the base of the house and the board is exposed for about two and a half feet to the air, but goes down from the top of the skirt 6 feet to the basement floor.
I used UGL waterproofing paint on the board before cutting and framing on both sides and used hydraulic cement between board sheets to close any gaps.
The board is in direct contact with the earth and shows no deterioation after 6 months.
The dirt has been dug up on the outside near the board for a inspection after 3 months and it looked very good.
I dont suggest using the board in this way without a waterproofing because the board will allow moisture to the inside but the moisture will show only as dampness. Their is a change in the color from tan when dry to grey when the moisture is evident.
With the waterproofing I found this material to be an excellent one to work with and I would suggest it in many applications with proper preparation.
Im an electrician by trade but have been on all sides of construction for many years which is probably why I dug up my work to check it out.

xxx

also metal flashing at all joints and edges and wood supports inside to stop the board from bending under compression.

I haven't seen anything to indicate that there is a difference in composition between hardibacker and hardiplank or hardipanel siding.

I believe its the same

Im not familiar with hardiplank or panel but if its similar to the backer board its good stuff, but the backer definately needs a preparation.
Im curious if the other two need as much prep when using under outdoor conditions.
Does it have a weave on one side like the backer does?
Is the hardipanel easy to work with?

Im not familiar with hardiplank or panel but if its similar to the backer board its good stuff, but the backer definately needs a preparation. Im curious if the other two need as much prep when using under outdoor conditions. Does it have a weave on one side like the backer does? Is the hardipanel easy to work with?

Very easy to work with, I would advise the shears to cut,
go to any Home Depot to get a visual on the product