Rainscreen and Comfortboard 80 Insulation
For a house in Zone 6 we are looking to mount cedar shingles onto horizontal 2x battens directly on top of Comfortboard 80 exterior insulation. Normally we would double the rainscreen here by adding vertical elements behind the horizontal but I’ve been reading that it may not be necessary given the porosity of Comfortboard. Any thoughts on whether this will be an adequate rainscreen assembly?
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From a practical perspective y0ur proposed assembly has almost all the attributes of a well functioning rain-screen, and I think will work fine.
If you are in BC it won't meet code because it lacks a dedicated vertical drainage plane.
Thinking about it again...
That's an awful lot of 2"x horizontal battens. You might still consider whether 1"x3"s both vertically and horizontally don't make more sense. It uses a lot less wood, and a lot less long fasteners.
Good point thanks
A nice set of photos of a vertical batten-horizontal cross batten assembly with exterior shingles is on the 475 blog: https://foursevenfive.com/blog/from-post-office-to-postcarbon-future-with-emerald-builders/