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Community and Q&A

Determining Need for Rainscreen

espositodesign_joel | Posted in General Questions on

Hey there,

Between 2016-2018 I built a tiny house for myself. At the time I was just starting to learn about building science and resilience, but based on the then-current manufacturer details and prevailing building methods in my area I neglected to specify a rainscreen behind my panel siding. The wall assembly is as follows:

Benjamin Moore Exterior Latex Paint
Nichiha Fiber Cement Panel Siding with Battens
7/16 ZipSystem Sheathing and Tape
Wood Framing with Fiberglass Batt Insulation
3/4″ Tongue and Groove Pine with thinned paint wash

It’s been about 5 years and I don’t see any signs of a major failure (e.g. bubbling paint, interior odors, softening of window trims, etc.). I’m wondering if it’s worth peeling the siding off in a high-risk spot (inside/outside corner or under window) to check the state of the sheathing, or if I should employ a less intrusive method like drilling a discreet hole in the wall finish and sticking a moisture meter probe into the backside of the sheathing after a rain storm. The plate height at the side wall is 14′, and the gable peaks at about 19′. There’s one horizontal joint in the panel siding with a piece of z-flashing on top of the lower piece of siding. I never pressure wash the house but we do get some pretty serious wind driven rain sometimes (50-ish inches of rainfall per year). Project is located in North Florida.

Will the drainage efficiency of the Zip save me? What about the fact that the panel isn’t “adhered” to the substrate like stucco would be? As long as it’s properly maintained/repainted and batten fasteners are caulked, will the paint prevent the siding from taking on water and the damage associated from solar drive of that moisture?

Wondering if anyone has experience with something like this, maybe a builder who has done renovation work on a similar wall assembly. Maybe I’m just imagining a catastrophic failure when in reality the failure would be more localized to fastener penetrations, under windows, service penetrations, etc.

Thanks for your time.

GBA Prime

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  1. Expert Member


    Nice house.

    I don't see much reason to worry - certainly not about anything catastrophic happening. Do rain-screen improve the robustness of any wall assembly? Sure - but they aren't necessary if the wall is well detailed, as yours looks to be?

  2. espositodesign_joel | | #2

    Thanks Malcolm, appreciate your feedback.

    1. Expert Member
      MALCOLM TAYLOR | | #3

      Your wall has good drying potential to the inside, and although cement-based siding is a reservoir cladding, it isn't anything like brick or stucco, which can move a lot of moisture to the sheathing with inward solar vapour drive. I don't see any real reason for concern, but I'll be interested to see what others think.

  3. Expert Member
    Deleted | | #4


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