Replies

1. 
   MikeFitz | Oct 07, 2005 04:56pm | #1

   My understanding is that moisture absolutely will get behind the siding, and that is one reason to use housewrap or felt.  Caulking the lap edge, if I am understanding you correctly, would only seal in the moisture and cause more damage.  The lap edge may provide a way for whatever moisture that gets behind the siding to escape.  That is why many advocate a rainscreen design.  I think you want to seal, i.e. prime, each individual board (hardi and many other lap siding choices come pre-primed) before installing, but I wouldn't run a bead of caulk under the laps.  I would use felt strips under your butt joints and caulk them, however.

2. 
   YesMaam27577 | Oct 07, 2005 05:18pm | #2

   Just like Mike said -- DO NOT caulk the bottom edge of any lap siding. Although you need to prevent water from getting in, you must also allow a way for it to get out.

   Because it will get in, no matter how hard you try to keep it out. It gets in in the form of humid air. Then the cooler night temps condense it. And if there is no way for it to get out, it will eventually rot the sheathing and framing.

    

    

   Unless you're the lead dog, the view just never changes.

1. 
   Sailfish | Oct 07, 2005 05:32pm | #3

   I'm in agreement with you two. That makes valid sense to me as well,

   I just see it done EVERYWHERE however. Whether its Hardi or wood siding.

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