Sealing tapes for Polyiso insulation and OSB
artisanfarms
| Posted in General Questions on
What are current recommendations for a sealing tape for OSB sheathing and for externally applied Polyiso insulation board? I’m getting ready to install my polyiso and would like to tape the OSB first. Also, once the polyiso is up, I’d like to tape it’s seams before installing the rainscreen, so, what would be a good tape for the polyiso. If it matters, the house is located in Central NY
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Replies
I've seen a few articles trying to compare tapes -- such as https://www.greenbuildingadvisor.com/article/two-wingnuts-describe-their-backyard-tape-tests and https://www.greenbuildingadvisor.com/article/return-to-the-backyard-tape-test
Notable takeaways: For your exterior insulation, "Foil-faced polyiso is very easy to tape; almost any decent tape will work." OSB is harder, but it seems like Zip System or other high-end acrylic tapes should work respectably (and taped OSB behind insulation will be a substantially less demanding application than taped OSB directly behind siding)
I like to use foil tape for the polyiso since it both sticks like crazy and also keeps the foil facing appearance (a bit OCD maybe on that last part :-). Flashing tape works fine too.
I don't normally tape OSB so I can't really comment on that.
Bill
I can attest to the stickiness of the 3M 8067 listed in Martin's tape test. It sticks to OSB, and stays there from what I've seen. the 3" x 75' roll tapes about 8 sheets and is easily wide enough to cover all nail heads, and span corners.
What tape is known to hold up after five winters in a moderately cold climate? That is an important question not answered above.
I’ve personally seen the foil tape still holding up after 20 years or so. I haven’t taken things apart specifically to check on the plastic flashing tapes, but I’d expect they’d hold up just fine too.
Bill