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

Flush-mount exterior electrical boxes in board & batten with rigid foam and rainscreen?

benrush | Posted in GBA Pro Help on

Good evening all,
I’m still working thru issues involving board and batten over strapping and rigid foam. Now I’m looking into the exterior electrical boxes (for outlets and for lights).
I’d like the boxes to be flush-mounted, with the “rain screen” (do we still call it a rain screen if the strapping is horizontal?) space serving as a conduit chase. That would minimize penetrations of the insulation and WRB- while avoiding surface-mounted conduit.
Important note: I’m in the Chicago area. Here, all electrical boxes have to be steel, and all wire has to be inside EMT or conduit. No flexible metallic cable or Romex allowed.
Initially, I had planned on 5/4 board for strapping, but now I realize that won’t leave much depth for electrical boxes- so I’m considering 2x strapping instead.
At this point, I’m looking at ordinary steel boxes and mud rings, with an as-yet-unidentified weather-tight gasketed “cover” on the outside.
1) Is there a better approach? 2) Does this “as-yet-unidentified weather-tight gasketed cover” actually exist? -or is it only in my imagination? 🙂
Thank you so much for your help.

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.


  1. benrush | | #1

    Sorry. I meant to attach this sketch before posting.
    Thanks again for any and all help you can provide.

  2. Expert Member

    Rather than a gasketted cover the typical detail is a site made, or manufactured, base for the exterior fixtures. They generally are slightly proud of the siding for easier flashing and sealing.
    Something like this:

  3. davidmeiland | | #3

    Take a look at this product line:

    I have used the vertical retrofit version with B&B siding. The electrician stubs a wire out of the wall and you bring it out through the middle of a siding board. You carefully carve out a recess in the foam and insert the box with a bushing around the wire.

  4. benrush | | #4

    Malcolm and David,
    Thank you both for your feedback.

    Can a site-made block or a manufactured base (like the SturdiMount) accommodate an electrical box and EMT or conduit? It seems like this sort of thing would be easy to use with Romex, but in the Chicago area, everything is hard-piped.

    David, has a LOT of products- but most seem to be for Romex. This one looks pretty close but it's actually DEEPER than I wanted(Careful what you wish for, right?) because I'm hoping to use the rain screen area as a conduit chase- so that I don't have to penetrate- or even "carve"- the insulation.

    Thanks again for your advice.

  5. Expert Member

    Apart from having to extend the boxes with a mud ring, what do you see as the difference between what you are doing and the way exterior fixtures are ordinarily mounted in siding?

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |