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white29 09-18-2007 03:35 AM

Hardiplank and new windows
Hello to all,I just discovered this site and could use some advice. I'm doing a garage remodel and ordered Hardiplank siding(I dont like vinyl,though the rest of my house is). A problem I can see that I'm going to have is that my new windows have what's called an "integrated J channel" built in. What this is is a 7/8"gap between the nailing flange and the attached window casing/trim.The channel is meant for the siding to tuck into behind the trim.This is all well and good,it will make for a nice clean installation. The problem is that with the siding ends behind the trim and in this channel I wont be able to caulk. Any suggestions on how I might flash this, or other ideas? The other problem,which I spoke to the window manufacturer about, is that this channel is not wide enough to accomodate both foamboard and the siding,so I guess no foam on this project. But thats another story. Thanks in advance for any ideas.

AtlanticWBConst. 09-18-2007 04:54 AM

Generally, all windows (like you described) are installed with exterior casing trim around the window. That 3/4" casing slides under the flange surrounding the window. The siding is then "butted" into the casing trim. It is not butted into the window itself.


white29 09-18-2007 10:53 AM

Thank you,Atlanticwbconst. I had already figured that as an option. The problem with that is that Hardiplank (I believe) requires 5/4 trim and the channel gap is only 7/8. I guess I will have to sand or rout off some of the trim to fit into the channel . Right? I don't believe this was the window makers intent,but that's what I'll have to do.

Big Mike 09-19-2007 10:12 PM

Hardiplank does not require a 5/4 trim, a 3/4" trim is perfectly acceptable and will slide nicely into that 7/8" channel on your window then allowing you to butt the siding directly into the 3/4" trim. The siding is 5/16" thick, two layers will only protrude 5/8" leaving it 1/8" short of the face of the 3/4" Hardi-Trim.

Originally Posted by white29 (Post 63568)
Thank you,Atlanticwbconst. I had already figured that as an option. The problem with that is that Hardiplank (I believe) requires 5/4 trim and the channel gap is only 7/8. I guess I will have to sand or rout off some of the trim to fit into the channel . Right? I don't believe this was the window makers intent,but that's what I'll have to do.

AtlanticWBConst. 09-19-2007 10:23 PM

As mentioned already - Hardie-Plank does not require 5/4 Trim.

white29 09-22-2007 07:53 AM

I got some bad advice then.My siding is on order,I've never even seen the stuff so I've not had any to play around with.My local lumber yard told me that I needed to use 5/4 trim, and the 1/8 differance between the Hardiplank overlap(5/8) and the 3/4 trim did'nt seem like enough.Needless to say I've already got most of the trim done in 5/4 so I guess I'm stuck with it. I'm thinking that maybe I'll try the siding tucked into the J channel or use 3/4 trim around the windows with some sort of molding at the edge to mmatch the thickness of the 5/4 trim.

bartels 09-22-2007 09:29 AM

we are redoing a barn that we have and would like to know if the hardiplank would be a good source to use or should we stick with pressure treated plywood?

XSleeper 09-23-2007 02:17 PM

You actually got good advice when told to use 5/4 trim. Since you have the integrated j-channel around your windows, you need trim that is thicker than the j-moulding, so as to be able to cover it up, and run a bead of sealant around it to seal it off. You can only do that if the trim is wider than the window's j-channel. If the trim was exactly as wide as the integrated j-channel is, you'd have a sloppy mess if you tried to caulk that seam.

Additionally, the hardiplank will look great with the 5/4 trim, I use it all the time. But 5/4 thick trim is not "required" in every case. But it sounds like based on the type of windows you have, they suggested the best thickness for you.

Tucking the hardipanel into the integrated j-channel is a terrible idea because the edges could never be caulked and the perimeter of the window would then become an entry point for water to get behind your siding.

white29 09-24-2007 07:49 PM

Good to know X-sleeper and thanks because i've been in a bit of a funk about this. The idea of slipping the siding behind the J-channel did'nt appeal to me either due to what you outlined. I thoughtI would try to do something extra with a flashing if I went that route.Would I be better off to A).Use 3/4 trim around around the windows,which would slip into the J-channel and fir out trim edge to match 5/4,(no problem caulking) B).Use 5/4 trim at windows but rout inside edge so it fits behind J-channel, or C).Butt 5/4 trim up to casing on outside of J-channel. ?? Option C seems to be what you are recommending, but that leaves the 7/8 J-channel empty.I'm not misunderstanding , am I?

Learn2Build 05-28-2010 11:57 AM

I know this post is quite old, but recently I have run into the same issue. I am not trying to jack your thread anything , but I am new to forums & whenever I do a search this thread and another keep coming up. I can't seem to find the final verdict of what anyone did to complete the task or maybe I am just missing it.
White29, it seems logical that you ended up butting the trim to the window to create the window casing instead of slipping it into the J channel, since that what it looks like in the pics that AtlanticWBConst. posted, but if you could please clarify if that was the case? Also, what kind of a gap did you use for caulk? Has the method that you used held up to the weather?

Scuba_Dave 05-28-2010 12:57 PM

One reason for the trim around the windows
If you ever need to replace the windows, you only pull the trim off
If you butt up to the window, you then need to remove siding to replace a window

Learn2Build 05-28-2010 01:28 PM

Scuba_Dave, I agree with you and I think it looks better too. So, do u think butting the trim against the window with a 3/16" gap and caulking that is better than routering the trim to fit into my 1/2" j channel is better?

Scuba_Dave 05-28-2010 02:40 PM

Are you siding with hardi plank - cement board ?
I have not used any J channel on my house w/Hardi boards

Learn2Build 05-28-2010 02:48 PM

Yes, it was going to be CraneBoard CB7 vinyl siding, but decided to go with Hardi plank after the windows were installed. I started a new thread if this helps. Labeled: Help! Casings around window with integrated J channel?

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