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Question about dense-packed cellulose wall insulation coupled with a service cavity in new construction

WBowling | Posted in Energy Efficiency and Durability on

Hi all,

I’ll be starting work on a new house this summer in Kentucky (Zone 4a, mixed-humid climate). My plan is for a stick frame house with 2×6 walls. I will be using ZIP system as my exterior sheathing and air barrier, and plan to use dense-pack cellulose in the stud cavity. I really like the idea of including a wall service cavity to account for any future work to the house, but I am a bit unsure as to the best way to install the service cavity and maintain the integrity of the insulation. As I see it, I have two potential options.

Option A: Have the dense-pack installed behind Insulweb, then place horizontal strapping across the stud face.

Option B. Have the dense-pack installed behind Insulweb, then place OSB on the interior stud face, then create my service cavity with strapping.

My instinct is that Option B would be more resilient over the lifetime of the house, but I also realize that I may be introducing problems by placing a vapor barrier (in the form of OSB) into the inside of my wall stackup.

Any thoughts would be greatly appreciated!

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  1. GBA Editor
    Martin Holladay | | #1

    OSB is a vapor retarder with variable vapor permeance. It is not a vapor barrier. Installed as you propose in your climate zone, it won't cause any moisture problems.

    Here is a link to an article with more information on this topic: Service Cavities for Wiring and Plumbing.

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