A Review of Siga Wigluv Air-Sealing Tape
To seal air leakage at OSB seams, first use a primer, and install the Wigluv tape with a J-roller
Every house needs four control layers. In order of importance, these layers need to provide:
- 1. Water control
- 2. Air control
- 3. Vapor control
- 4. Thermal control
The building codes have dictated the levels of thermal control and vapor control that builders must adhere to, and nearly every builder in the U.S. knows off the top of their head the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of the insulation in their walls and attics.
But until recently, the building codes haven't addressed air control. The 2012 IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code. now dictates that builders in my climate zone (Zone 2) need to achieve a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. result of 5 ach50 or less, which is actually pretty tight. This new requirement will make quite a few builders need to research air-sealing methods in order to reach this level of airtightness.
Codes need to do a better job addressing water control
As an aside, it's interesting that building codes barely touch on water control, which is of course the most important control layer on any house. What difference does it make what R-value your wall has if water is getting into that wall through a leaky window or a poorly sealed plumbing or HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. penetration?
In my quest to build ever-tighter houses, I've decided that my goal is for every house I build to get as close to 1 ach50 as possible. Not every house I build will get to this standard, as I'm sometimes limited by the architecture or the weatherstripping of exterior doors. I've found that sliding glass doors, custom doors, "store front" doors, and other architecturally cool doors can really kill my blower-door test results.
Air sealing approaches
If you've followed my blog, you know that I've used a ton of different methods to air seal inside a house: spray foam, Owens Corning Energy Complete, caulk, etc. Using these methods, I've been able to get most of my houses below 2.5 ach50. But to reach my goal of 1 ach50, I've decided to take a page from the PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. playbook and tape my exterior sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. seams.
After reading Martin Holladay's “Backyard Tape Test” article from the March 2013 issue of Fine Homebuilding, I thought that Siga Wigluv was the clear winner as the best tape for OSB sheathing seams. Martin's article says that it's best to use a primer, and I fully agree.
I bought my Siga tape (along with the necessary Siga accessories) online from Small Planet Workshop. I recommend using a J-roller to roll out the tape and ensure good adhesion. To see a step-by-step demonstration of the installation process, check out the video below, as well as the series of photos and photo captions.
Unfortunately, I've been waiting on the rear and front doors for this house, so I've not yet been able to perform the blower-door test. I'm expecting this house to get very close to my goal of 1 ach50.
I'll post an update to this blog post once I get the blower-door results. Overall, I'm really happy with this Siga tape and I think this method of addressing air control is superior from a “best practice” standpoint.
Matt Risinger is a custom builder and whole-house remodeling contractor in Austin, Texas, specializing in architect-driven design and fine craftsmanship. His company, Risinger Homes, uses an in-house carpentry staff and the latest building science research to build dramatically more efficient, healthy, and durable homes. You can read more examples of Matt's writing at Matt Risinger and the Green Building Blog.
- All photos: Matt Risinger
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