Replies

1. 
   dovetail97128 | Oct 26, 2008 07:18pm | #1

   Hardie recently put out a bulletin that says their primed hardie siding should not have caulk applied at the butt joints.

   Still OK to caulk the unprimed siding but you will void the warranty if you caulk butt joints on the prime.

   They can't get your Goat if you don't tell them where it is hidden.
1. 
   Westcoast | Oct 31, 2008 07:12am | #5

   All hardie siding is primed. Are you referring to the hardie-plus finish vs. primed?

1. 
   dovetail97128 | Oct 31, 2008 08:52am | #6

   Been awhile since I used the stuff but it didn't always come primed. Maybe now it all is.
   They can't get your Goat if you don't tell them where it is hidden.

1. 
   MikeHennessy | Oct 31, 2008 02:35pm | #7

   It's primed -- just primed a subtly FC gray, so ya can't tell it's been primed. ;-)

   Mike HennessyPittsburgh, PA

1. 
   dovetail97128 | Oct 31, 2008 03:56pm | #8

   Snork.
   They can't get your Goat if you don't tell them where it is hidden.

2. 
   arcflash | Oct 26, 2008 07:21pm | #2

   I wouldn't if I were you. If you leave those joints unfilled, the ony line of defense that you have for water infilatration right there will be housewrap, which is supposed to be your last line of defense and is not to be trusted.

   It depends on the brand of fiber-cement. James Hardie recommends butt-joint flashing paper. This is a change as of about two years ago when they recommended caulk and paint. Fiber cement is very stable, but the substrate to which it is attached is not. I've been filling and re-filling butt-joints for three and a half years now. It is too late for butt-joint flashing for you but I would say caulk and paint might be fine. You want polyurethane caulk, and 100% acrylic latex paint with primer. Once in awile check on those joints to make sure they are holding.

   Edit: an untreated joint will void the warranty also, so right now, its just about protecting your home.

   
   

   ---

   Edited 10/26/2008 12:23 pm ET by arcflash

3. 
   BoJangles | Oct 26, 2008 08:11pm | #3

   Well....I think uncaulked joints look awful.  It's probably a good idea to use flashing behind each joint whether you caulk or not.  Maybe your installer did this?

   I find that it works best to leave a 1/8" joint and caulk.  The problem is that all caulk shrinks somewhat and you do get a recessed joint line, but it looks 1000% better than an uncaulked joint and certainly is more waterproof.

   I find that Certainteed siding does move a bit with changes in temperature.  That's why I leave the slight gap.  If you butt them tight, you don't have enough caulk to expand and contract.

   I prefer Big Stretch in the joints if I'm going to paint (which I always do)  I've tried all kinds of caulk and I find that seems to shrink the least.  If you don't use latex caulk, be sure to check the curing time of the caulk.  Some of them take a week or more to cure and if you paint before they cure, the paint will flake off.

   In your case, I would prime the joints to make sure the butt ends are sealed, caulk, and then paint with two coats of 100% acrylic latex paint.

    

    

    

4. 
   Piffin | Oct 26, 2008 08:13pm | #4

   For the kind of squabble you are deep into, no advice will help other than on a practical basis.

   What you need is documentation directly from the manufacturer. Google and contact them.

    

    

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