Airtight sheathing: sealing nail penetrations?
I have been reading as much as I can find on the airtight exterior sheathing method. I am still left with a few questions:
1. When taping the sheathing seams (1/2″ cdx ply in my case), should nail penetrations in the sheathing, both near the seams and “in the field” also be covered? Eric Whetzel caulked and taped every nail in his ZIP sheathing in his Urban rustic article: “Air sealing the exterior sheathing” though it is unclear to me whether this step is necessary when my WRB (Tyvek) will be applied over top of my sheathing.
2. By the same token, should a self sealing tape be strategically applied to the sheathing to seal subsequent fastenings of the WRB and siding which will penetrate the sheathing?
I suppose if I just tape my stud layout with continuous top to bottom strips I could cover existing nails and hopefully seal all future ones. For reference, based on recommendations found on this site, I’ve ordered many rolls of 3M all weather flashing tape 8067. 3M claims this tape is able to “pass nail sealability before and after thermal cycling”
Thanks so much! This website has been an informational gold mine for me during my construction.
-Tanner Cunningham
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Tanner,
Most builders who use exterior wall sheathing as their primary air barrier don't seal each fastener, and they still get a good blower-door result. I would say you can ignore the fastener penetrations, since the amount of air leakage associated with these penetrations is minor.
Eric Whetzel clearly disagrees with me, and he raised the bar on air sealing measures in order to achieve his goal. You'll hear from all kinds of builders on GBA -- many of whom have lots of time on their hands, and are eager to achieve a blower door result that is lower than any result ever reported. We're all grateful to these people, for the examples they set and the stories they are willing to share.
When you build your own house, you get to set your own targets, based on your energy performance goals and your budget.
Martin,
thank you for the speedy reply and balanced perspective!