Contractor needs guidance on sealing ICF exterior envelopes
Contractor has worked on ICF houses over the years and has several ideas on how to seal around all wall penetrations
January 11, 2019 by canadiancontractor
We have had a series of sponsored posts from NUDURA, on technical aspects of building with Insulated Concrete Forms (ICFs). Here is a question that was generated by the series, from contractor Kayne…
I have worked on eight ICF houses over the years and I have always found it problematic on how to seal the exterior envelope, especially in the window box areas. With vinyl flange windows or vinyl inserts throughout a wall assembly and multiple assorted penetrations making it difficult to seal against the foam, do we:
A. Cut back to the concrete so the flanges are sealing against a solid monolithic slab, sealing the flanges with caulking?
B. Cut the flanges off totally and use foam rod and caulk across all wall penetrations?
C. Use pan flashings within all openings in the ICF?
When we were doing cementitious coatings on ICF, I had some success using the pan flashing method as long as I was able to get in before the windows were installed (which was rare ). I found using a fiber-coated membrane in conjunction with a water-based primer on the ICF worked but I always sleep lightly wondering if I went to get a call in the middle of a rainy night.
I honestly try to stay away from ICF homes if I haven’t seen the engineering and design work behind all the wall penetrations and know that they have been addressed.
I also worked at a EIFS and steel panelling plant trying to get certification for window installations from Hershey Warnock. It was one of the most intriguing educations I have had defining how to keep water out of an envelope. It was a while back but I think we ended up getting the certification which took over two years and countless tests.
I can’t imagine that happening in the field and some contractor has one day’s worth of training under his belt and figures he can put up in ICF foundation. I would enjoy seeing their opening details just so I get a better understanding and maybe learn something new.