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

Flashing tar paper WRB and sealing CCSF air barrier (Lunos install)

pjpfeiff | Posted in General Questions on

I’m installing a pair of Lunos e2 HRVs in a wall section like this:
 – drywall
 – rockwool
 – 1″ CCSF
 – 1x plank sheathing
 – tar paper
 – transite siding
 – thin layer of foam
 – vinyl siding
So the tar paper is the water control layer, right?  How do I flash this?  My current plan is to use a ROFLEX 150 gasket, cut a slit in the tar paper, and tuck the top edge of the gasket under the tar paper while leaving the bottom edge on top.  But how to do I keep water out of the slit?  Roof seam tape?  Black Jack?  Or would Tescon Vana or foil duct sealing tape work?  (Doesn’t look like that is an approved use, but I already have these).

For better or worse I think the CCSF is the air barrier (drywall was not detailed as such).  The Lunos instructions would have me cut a hole leaving only 1/16″ around the tube.  Should I go with that or cut a larger hole so I can push caulk into the gap in the sheathing and then add canned foam to the gap in the existing foam?

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. PAUL KUENN | | #1

    Paul, if done correctly the spray foam should be the air barrier. But, what is that "thin foam" mentioned and is it taped as if an air barrier or WRB? That can be your WRB and it could be taped with the Tescon over the Lunos gasket. I install a fair amount of Lunos but usually with a better WRB from 475.

    1. pjpfeiff | | #2

      Thanks. I don't really know what the purpose of the "thin foam" is. I've assumed that it's a standard feature included when covering old asbestos shingles with vinyl. Or maybe it's marketed as adding R-value (even though it's too thin to do much)? I kinda doubt it's a WRB, but if it were, would you just tape the gasket directly to it with no lapping? I did chat briefly with 475 today and they seemed to indicate I could use Tescon on the tar paper, but maybe I should have pressed them to be sure that's what they really meant.

      Anyway, maybe I'll see if I can find a seam in that foam to see if it is taped.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |