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

Cinder block home – mold on drywall

schatzyman | Posted in General Questions on

Hello —

I have a 1960s construction cinderblock with brick facade quadplex that is apparently experiencing mold issues.  The problem was discovered after a TV that was mounted to drywall on an exterior wall fell off, removing some of the drywall.  On the backside of the drywall was the appearance of mold. 

There is no insulation inside the cavity, and the walls were framed with 1x furring strips attached directly to the cinderblock.  I have attached a picture of one of the pieces of drywall that was removed. 

I’m assuming that the water vapor was moving from the outside humid air & condensing on the backside of the cool drywall? (the room is air conditioned via a window unit).  I also know in my climate (4a) a general vapor barrier would not be recommended… but is there a remedy short insulating all of the exterior walls with foam?  

Thank you in advance!

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. schatzyman | | #1

    *updated to fix picture attachment...

  2. Expert Member
    Akos | | #2

    I'm in a bit colder climate but still pretty hot and muggy summers. Older all masonry buildings with just strapping+plaster on the interior generally stay mostly mold free unless there are water leaks. Occasionally there is a bit of black spotting on the back of drywall but nothing like that. I would check for bulk water leaks first before doing anything else.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |