HARDIE BUTT JOINT SPACING

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Butt-Joint-Spacing

Hardie Butt Joint Spacing?

Originally Published May 31, 2011 in the online forums of JLC - The Journal of Light Construction.

I've been looking for spacing all over Hardie website cant find anything. Any help would be great. ~ NW Architect

Well, the pieces at 12 feet long so any wall surface 12'-0 1/4" wide or less gets one piece. On longer runs, stagger the joints as widely apart as possible, and keep your factory ends at the butts. ~Dancing Dan

I think he means whether you have to leave a space at the butt joints like you have to against the window trim & corner boards. I believe the answer is no, but it's been a while since I've done any Hardie so I'm a little rusty. ~TSJHD1

Unless Hardie has changed this (which I doubt), it is 1/8" and it should be caulked. ~Tom

These are the install specs for your area of the country as of January 2010 and are the most current http://www.jameshardie.com/pdf/install/hardieplank-hz5.pdf No gap and no caulk.....the joint should be counterflashed. ~Alaskan Son

I always gap it 1/8"+. Any less and the caulking may smoosh out and look really ugly. 1/4" is better, but can be a little more difficult to make look good. ~Michael

Is that on the pre painted that you leave a gap and smear it full of caulk? Seems like a good way to ruin a good looking job. I think I would prefer to counterflash and not caulk if at all possible. Maybe the caulking would not be so bad if you were going to paint everything but not so sure about the pre painted stuff. I will say that the last job we did the color match of the pre painted siding and the caulk was very good but the sheen was what made it stand out. Or maybe just have to teach folks to caulk with less mess. After all these years I still have a hard time believeing how many folks cannot run a decent caulk joint. ~NW Architect

Actually THAT detail is smack dab in the middle of their install sheet. These days they recommend (uncaulked) "close contact" (or some such vague description) with a flashing behind the joint. A caulked 1/8" joint is still an option. ~Joe

If you haven't done so already, download Hardie's best practice guide. I don't know if the installation techniques vary by region as their product does.
In my area, latest guidance calls for factory ends preferred or priming cut ends, moderate contact, flashing behind the joint, and NO caulk.
I like the prefab Tamlyn plank flashing because it's fast & easy. http://tamlyn.com/xtremetrim/Plank%20Flash.html (LINK DEAD) New Link - http://xtremetrim.com/products-xtremetrim.php?i=0&s=XtremeTrim%20Butt%20Joint%20Flashing

PlankFlashing

Here are some photos from one of our jobs. The furring strips were part of a rainscreen system. ~Joe  Adams - Deep Creek Builders, Inc. - Houston, Texas

image 22789

image 22790

Is that on the pre painted that you leave a gap and smear it full of caulk? Seems like a good way to ruin a good looking job. I think I would prefer to counterflash and not caulk if at all possible. Maybe the caulking would not be so bad if you were going to paint everything but not so sure about the pre painted stuff. I will say that the last job we did the color match of the pre painted siding and the caulk was very good but the sheen was what made it stand out. ~m beezo

Or maybe just have to teach folks to caulk with less mess. After all these years I still have a hard time believeing how many folks cannot run a decent caulk joint. Prefinished stuff is pretty uncommon up here, so yes it would be painted. I would do prefinished stuff the same way, but like you said you have to do it right. I have a hard time trusting anyone but myself to do any caulking of any kind. ~Michael

These days they recommend (uncaulked) "close contact" (or some such vague description) with a flashing behind the joint. This is how I have done all my Fiber Cement jobs since allowed. I also have never installed anything but prefinished.. It has all been remodel work however. I have not seen too many caulked joints that looked good a year or so down the road. I have seen some horrible ones, but know that there are likely some good ones out there. Deep creek, it looks as if you may have a pre-made corner and then a 1x hardie trim next to that? Cant really tell in the picture..... whats going on there. Good work with the rain screen and counter flashing. ~Nate Dizzy you know who izzy

Well I'm obviously going back a ways, because I remember Hardie used to call for a field joint, caulked. I too disagreed with the caulk, so we decided to leave a 1/16" gap, and not caulk. And that detail looks quite good. Hardie has changed their install details a few times since the product came out. Probably haven't changed much in past few years, but I also remember when they called for only 1" clearance off roofs. (Now it's 2") Edit: Actually, as my mind starts to come back (and I found an old install guide), the caulked 1/8" butt joint used to be an option, which we opted to do when installing unfinished. But when installing finished, the 1/16" gap looked better than butting the pieces together, and since the ends were painted, no caulk looked fine. ~Tom

Deep creek, it looks as if you may have a pre-made corner and then a 1x hardie trim next to that? Cant really tell in the picture..... whats going on there. Good work with the rain screen and counter flashing. ~Nate Dizzy you know who izzy

Nate, you're exactly right. It's an Azek corner and Hardie trim with a 3/8" reveal. I added this and a couple of other details to dress it up. ~Joe  Adams - Deep Creek Builders, Inc. - Houston, Texas

I guess you have to usually special order and ship everything to your neck of the woods anyway so prefinished isn't much of an upgrade? Most all caulking jobs I have seen also look bad a year or so down the road (and sometimes even from 1/4 mile or so down the road). In my experience its because the caulking was just done sloppy, or the gaps were too small. Caulking is more like an art form I think that not very many people should attempt. So maybe no caulking and close contact with a "tin shingle" is a better option. ~Michael

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