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how to block & flash exterior fixtures on exterior-foam assembly

neutral_grey | Posted in Energy Efficiency and Durability on

I must not be searching for the right terms – what’s the right way(s) to block fixtures on a wall with exterior foam and rain-screen?  frost-resistant sillcocks and exterior lights/outlets specifically.  My current project (a ~temporary micro-house, essentially) uses 3″ of exterior (overlapping 1.5″); permanent house will be much thicker.  For today caring might be a bit overkill – but a good opportunity to spend a year or three with the result before I commit to it for decades …

– blocking sits directly on the foam? (eg ignoring what should be the rain screen?  But if not done this way, you have ‘naked’ electrical or plumbing jumping the ‘gap’)
– the z-flashing on the top margin is simple enough, but on the bottom do you just use a deeper flash, between the face of foam to face of sheathing?
– some fixtures benefit from recessing:  outlets obviously, but also likely sillcocks (mechanically protected, less wind-washing helps freezing on the margins or when hose was left on).   Inset them through just one of the two layers of foam to keep partial thermal bridge protection?  Or inset them all the way to the sheathing?  

That last one would essentially imply an “innie” window frame box to flash, it would appear, but it could be a really nice looking result.

Any existing detail schematics would be fantastic; thanks!
Norm Abrams Best Tricks of the Trade II - This Old House

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Replies

  1. neutral_grey | | #1

    bump - any advice greatly appreciated here!

  2. rockies63 | | #2

    Matt Risinger has a few videos on Youtube about mounting blocks and high performance wall systems.

    Mounting Block details
    https://www.youtube.com/watch?v=sV3zzrRKr7A

    A Better Exterior Hose Bib
    https://www.youtube.com/watch?v=JItfWP7Li-8

    Exterior HVAC Boots
    https://www.youtube.com/watch?v=A6B79JHVOQQ&t=39s

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