hey all fine homebuilders
im working on a house that i finished 9 years ago. i thought i top notch job on the siding install using all the things ive learned in 25 years as a professional carpenter/builder. im trying to stop wind driven rain from getting behind hardiplank siding. i noticed dried water stains coming from the lap on 8.25″ hardi with a 7 ” reveal. opening up the wall, water had gotten in and backed up above the windows until it reached the top of a siding course and then made its way out. the siding actually laid fairly flat on the wall (blind nailed)although there were a few gaps (less than 1/16 ). Im almost positive the water worked its way up the 1 1/4″ over lap via high winds or cappalairy action. after removing approx 280 sq feet of siding and wet moldy sheeting i want to make sure this doesn’t occur again. im considering calking all the lap joints to prevent water from getting in. do you all think this is a good idea?
it is not unusual to have 50 mph wind & rain here in the pacific northwest
Replies
You should have flashing behind the butt joints that overlap onto the lower course for water protection.
I'm on the South Oregon Coast, have installed a lot of the F/C siding and in some very exposed locations and have not had the problem you're seeing.
One thing you might look at is possible water entry at the butt joints and corners...I flash behind the butt joints and wrap corners with Ice and Water to provide a second defense against weather should the caulking fail (which it invariably does).
(BTW, I picked up that method a long time ago on this forum).
Water will wend its way over some strange paths sometimes and the entry point is not always what it appears to be.
I blind nail F/C with a siding nailer, but sometimes, especially on an older house where the walls may not be really straight anymore, I'll facenail if the lap is standing proud. A few facenails here and there won't really be noticeable once the siding is painted.
Like others said, cut some felt splines and put those in the butt joints. I think hardie changed their install info, saying you do not need to caulk the field butt joints, but I still will, it look much better that way. I still use the splines, just as a back up if the caulk failed. Also, what type of caulking are you using? I know painting contractors in my area that always use Dap Alex II caulking for fiber cement. Dap themselves will tell you that you absolutely should not use that for FC, that it is not meant for FC and will fail.
Painters typically use cheap caulk
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