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

Zip system R sheathing

eightinchnails | Posted in General Questions on

I am in climate zone 4- Portland, OR

I would like to do a 2×6 wall, cellulose or fiberglass batt insulation, zip system r sheathing rain screen and cedar siding.

My question is by puncturing the foam under the sheathing am I losing the value that I am trying to create by having a layer of foam.

Thanks for any insight. Cheers

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

  1. mackstann | | #1

    This thread explored the topic and, after a brief scare, it was determined (see comments #17, #21, #29) that the reduction in R-value is insignificant -- perhaps somewhere between .03% and 2%.

  2. Expert Member
    Dana Dorsett | | #2

    With shingles nailed directly to the ZIP you'd be running nearly an order of magnitude more nails than with clapboards, and you'd be at the high end of those estimates.

    But with Zip-R the foam is on the interior side of the OSB. There's no fastener retention advantage to nailing any deeper than the thickness of the OSB anyway, so going with reasonably short nails that won't fully penetrate the foam, the nail points are all thermally-broken, and the hit would be small. This presumes your rainscreen approach is a plastic mesh such as Obdyke Rainslicker.

    With a rainscreen formed with 1x furring held on by timber-screws 24" o.c. the siding nails wouldn't penetrate the foam at all, and the only thermal bridging would be the timber-screws, which is miniscule.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |