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

Foundation finishing over exterior Comfortboard insulation

CMylks | Posted in General Questions on

Hello all, we are working on a plan to cover the 1-3feet of exposed exterior insulation on the foundation between the soil level and the start of our siding (I say 1-3 feet as it’s 1 foot on the north wall, and the west wall has a slope so the exposed portion is up to 3 feet on the lower end of the grade). We are considering to use the ‘belt and suspenders’ approach described by GBA member Riversong (see post from 2010: https://www.greenbuildingadvisor.com/question/question-about-finish-over-exterior-foundation-insulation#comment-105581). 

He describes using surface-bonding cement over metal lathe / 1/2″ hardware cloth to cover the exposed, above grade portion of exterior insulation.  In our case, the insulation product we’ve used is the semi-rigid Rockwool Comfortboard 80 not rigid foam. Our local contractors supply guys have cautioned about the cementitious coating over Rockwool due to moisture issues – they fear that there could be efflorescence over time on the cement coating.

I wonder if anyone has applied a cementitious coating over Comfortboard before, or has any other suggestions. We wondered about installing a vapour/air barrier between the Comfortboard and the metal lath for exampe to stop/slow moisture transfer to the cement coating for example?

(Note: we are in Eastern Ontario, climate zone 6)

Thanks so much for any comments, tips or suggestions. 

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.

Replies

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |