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

Contractor forgot to protect bottom of exterior foam wall

user-1112710372 | Posted in General Questions on

I came home yesterday to find out my foremen forgot to protect the bottom of the exterior foam as planned. It’s just the garage and only 3/4” of EPS is exposed. Wall goes plywood then blueskin then 3/4” EPS then Henry rain screen then Hardi lap. It’s also 24” OC framing. I wonder if I can notch out the perforated flashing and slide it up after the fact? Is there any other way to protect it after the Hardi lap siding has been installed. Zone is Central Ca coastal. Thank you.

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. gusfhb | | #1

    A pic might help get better answers

    1. user-1112710372 | | #2

      Good idea I just posted. One of the guys had the idea of cutting down some of the Hardi trim we have and just nailing that into the foundation as a block. You would barely see it. Work days are precious here this winter in CA so losing one feels wrong by going back and tearing off siding.

  2. Expert Member
    Michael Maines | | #3

    Can't you just pull off the bottom course of siding and install the metal properly?

    1. user-1112710372 | | #4

      My last experience with Hardi was it was really hard to pull off the bottom row. But yes that would be ideal. Another idea was to just sikaflex or adhesive a piece of flashing to the 1/2 ply that will also cover the 3/4 foam. So stick a piece of 1-1/4 perforated flashing under there but adhesive it on.

    2. user-5946022 | | #5

      @michael Maines - can you explain how it is possible to do that when siding is nailed shingle style? I presume that would both destroy the bottom course, and possibly the course above it. Then how do they get the bottom course installed again - wouldn't that cause there to be exposed nails everywhere? I'm really trying to understand this...

      1. Expert Member
        Michael Maines | | #8

        I have never installed Hardie and I don't spec it for jobs, so I don't know exactly how it would work, but I have removed many square feet of blind-nailed cedar shingles using a shingle ripper tool and installed new ones using angled nails that become hidden once the new shingle is tapped into place. It's slow but effective.

  3. gusfhb | | #6

    I don't understand the picture!

    Concrete up to the building?

    How far back is the insulation[covered with the rainscreen I guess in pic]

    MAybe an L shaped piece of flashing and you can work it into the gap between the concrete and the foam and glue in place to the trim or whatever is above it

    1. user-1112710372 | | #9

      Oh that is confusing cause they bent the blueskin around the bottom of the plywood - which might not be right. But it’s 1/2 ply then blueskin

  4. bcornwellco | | #7

    - Tape it with Siga Fetrim or similar, UV resistant black options available too.
    - Paint brush coat it with a cement-like stucco material. Neighbors did this with their exposed basement foam wall sections, it was cheap and has lasted over 15 years.

    1. user-1112710372 | | #10

      You win the prize!!!! That is what I was hoping for. Something not perfect but good enough. Thanks

    2. user-5946022 | | #11

      Is the idea to only tape the bottom of the foam, and try to turn the tape up the foam? Anything else and I would be concerned about the tape holding any water running behind the rainscreen...

      I would be trying to get the perforated flashing in there because it not only protects the bottom of the ply (which is already protected with blueskin), it also protects the bottom of the EPS and that gap between the EPS and the back of the Hardi, as well as in between all the materials. I would be trying to keep critters out...

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |