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


p_550spyder | Posted in GBA Pro Help on

Hoping I can get some good feedback from experienced and knowledgable people. This is my first post. Recently I had an insulation winterization retrofitting program for wall insulation installed in my house. To note, I live Toronto, Ontario, so I’m in climate that experiences cold winters and hot humid summer. My house is over 100 years old, it’s a single brick home, with 2 x 4 structure exterior walls. Between the sheathing and brick it appears to have an air/rain channel approximately an inch in size. The walls are lath and plaster over the 2×4 studs. The contracting company drilled and filled the stud bays with an injection foam insulation called Air Krete from the inside and patched up the holes with drywall compound mud. I will need to now refinish those holes with some sanding and reapply more compound and then prime and paint. 

My questions are: 

1- I’m feeling a little unsure if I should have proceeded with this retrofit and now I’m worried about any potential of moisture retention producing mold and wood rotting, since this was a retrofitted application. Does anyone have any experience with such and is there any info or advice you could share for such application? 

2- Knowing that the house doesn’t have a plastic vapour barrier, I’m looking to repaint the walls with a good paint & primer that will help to act as solid vapour barrier, to create a good seal. Does anyone have any suggestions on what primer and paint to use? Was planning to repaint in the fall time. 

Appreciate all/any advice and input for both questions.
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. walta100 | | #1

    At this point the deed is done all that is left to do is hope for the best.

    I would not change anything at this point unless you were directed to by foam installers in writing or by the published instruction from the foam manufacture. At this point if there is a problem it is on them if you start changing things not so much.

    You could cut a hole in the wall if you wanted to know if a vapor barrier was install.


    1. p_550spyder | | #3

      It is and hopefully it won't result in any future issues. They insulated 70% of the exterior walls, (just last week) , a decided not to do certain walls as I'm planning to enlarge certain windows and reno my kitchen so would insulate those on my own once I get to those renovations. Cutting a hole now in the walls won't likely be of help since it's just been recent.I also don't currently have central air conditioning, so no conditioned air is running currently inside. But definitely no vapour barrier is in the walls, I know from some work I've done myself throughout the years.

  2. Expert Member


    1. I think people are a bit reticent to weigh in because we know so little about Air-Krete and what it does in a cavity in terms of moisture retention, and air-sealing.
    2. The biggest contributor to moisture moving though your walls is air leakage not vapour diffusion, and unfortunately paint doesn't do much about that. As you are not opening up the walls, your options are fairly limited, but I would suggest spending the majority of your efforts caulking and sealing air-leaks as effectively as you can.

    In terms of slowing vapour movement, plaster walls in older houses were usually coated with oil-based paints, which brings down their perms to around 2.0. That's already pretty low, but you could further reduce it to less that 0.5 perms with a coat of vapour-retarder primer before top coating, but I'm not sure doing that makes much of a difference.

    1. p_550spyder | | #4

      Hi Malcolm , I will work to caulk all around the electrical outlet boxes and any other areas as best as possible. My windows are super old and drafty but i'm intending to change them hopefully by next spring which will hopefully make for a more air tight house during the winter months and when I have central air installed for the summers. I will still aim to repaint with vapour-retarder primer and paint if they make such for top coat or possibly top coat with an oil based paint.

      I'm assuming it's beneficial to have weep holes along the perimeter of the brick walls, this way I have proper rain drainage and air run through the air/rain channel and doesn't have a negative impact in this case in anyway, correct?

      1. Expert Member
        MALCOLM TAYLOR | | #5


        Yes you want open weep holes at the base of the brick.

        1. p_550spyder | | #6

          Is there at all any way to periodically inspect if something sinister is transpiring in the walls, say during or after the heating season? Perhaps with IR camera or drilling an hole and placing some moisture detection device in the walls that might be available?

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |