GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Hardie window flashing

Jhelmick | Posted in General Questions on

Hi, I have a question regarding flashing windows when using Hardie lap siding. My contractor is currently working on siding install after removing old vinyl and windows, repairing rot, and installing new windows. Before the start of the project we discussed options for trimming the windows. I decided on aluminum J channel for a few reasons. It seems like a cleaner look, no caulk lines to look at (or crack, split, leak etc), and no face nailing trim.  My contractor thought that would be a good weather tight way to go.

Fast forward and he has completed a couple windows. I expected a flashing at the bottom corners to keep water on the face of the siding courses below. However, he has taped the top of the next full course of siding below the window to bring any water the travels the j channel and ends up behind the siding below the window back to the surface. Looking back at Hardies in for sheet it looks like the z flashing is for integrated j channel. And it makes sense now that wouldn’t work for non integrated j channel since the j channel would be in the way. Is taping the top of the new full row an acceptable way to flash in this scenario? Anything to be concerned about?


GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |