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T-111 code question

GBA Editor | Posted in Building Code Questions on

Can I use studs, Tyvex, 5/8″ T-111 siding — instead of stud wall, 7/16″ OSB, Tyvex, 3/8″ RS fir siding?
Basically, I’m trying to eliminate the 7/16″ OSB.

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  1. GBA Editor
    Martin Holladay | | #1

    That's a question for your local code official. There are too many variables for us to answer here.

    In some regions of the country, seismic or hurricane codes require strict bracing and nailing requirements for sheathing -- making your proposal impossible. In other areas, as long as the T-111 is adequately nailed, your proposal may be legal.


    The difficulty is that the Tyvek would be very vulnerable to damage during the time it was just stapled to the studs waiting for the T-1-11 and would likely get damaged then as well as during rough-ins and would be vulnerable to insect damage etc after the walls were closed in. I recently inspected a house where the builder had stapled up Tyvek directly to the studs and then gone over it with pressure treated 1x8 clap-boards. the Tyvek was in terrible condition inside the walls and insect infestation was a big part of it.

  3. GBA Editor
    Martin Holladay | | #3

    I'm not disputing your point, but here is a counter-example: 16 years ago I built a woodshed. I framed the walls with 2x4 horizontal blocking between the studs, 24 inches on center, and installed let-in 1x4 diagonal bracing. Then I stapled Typar to the studs and installed vertical shiplap boards as siding -- without any sheathing.

    Here's what's surprising: after 16 years of use as a woodshed, with open studs on the interior, the Typar looks and feels great. No holes, and it still feels tough. I would have guessed it would be shredded and deteriorating by now.


    I actually have a great counter example myself on my website even. The studio at the three waters lane house (the one I lost in my divorce) was pole barn frame, tyvek on purlins 28" oc with 1 1/2" XPS between them then 1/2" osb and cedar shingles. roof was Tyvek over 6" fiberglass and then the OSB and asphalt shingles. Not a residence, just studio use, but still going strong years later.

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