How to install a Window When Using a Self-Adhered WRB

The first time I used a self-adhered water resistive barrier was in 2019, on my own home.  I had recently purchased a 1950’s vintage Cape Cod design fixer upper that was built using board sheathing covered by 15 lb. asphalt impregnated felt.  I knew I wanted to improve the water management and air tightness of the structure but didn’t want to upgrade the sheathing.  I had been researching self-adhered WRB’s and decided that option would be the best fit based on what I was trying to accomplish.

For the exterior renovation at my home, the Henry Blueskin product was installed over the board sheathing. The assembly also includes a 3/8-inch furring strip for a ventilated rainscreen.

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How to Integrate a Window into a Water Resistive Barrier

The building science community talks a lot about control layers.  I’ve written on the topic several times, basic overview of these principles which can be found at: A Crash Course on the Four Control Layers.  Let’s take a deeper look at water resistive barriers (WRB) and how windows and doors need to be integrated into the WRB.

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Winnie Pretty Good House-Working with Huber’s Zip-R Sheathing

As builders and designers, we have so many ways we can improve the performance of a wall assembly.  Deeper wall cavities will allow for more insulation, double wall construction gains you the ability to move the air and/or vapor control to the middle of the wall leaving the inner framing cavity free for mechanical/electrical/plumbing (MEP) equipment.  Then there’s Building Science Corporation and Dr. Joe Lstiburek’s perfect wall, with the right ratio of continuous exterior insulation to interior cavity insulation that lessens the worries of vapor control.  Continuous exterior insulation can be designed in several ways, foam-based products, ridged mineral wool, wood fiber insulation, or nail base products.  And then there’s Huber’s Zip System R-sheathing, what we call on the jobsite, Zip-R.

Zip-R isn’t new, I first became aware of the product back in 2014.  What makes this product unique is that the continuous insulation layer is located between the exterior wall sheathing and framing.  This location simplifies the installation of CI and wall sheathing compared to the traditional location of the insulation, which is exterior of the wall sheathing.  And to add to the advantages of the product, in most applications, it is still a structural sheathing product when installed per Huber’s manufacturer’s instructions.  (Consult a structural engineer if there are any questions or concerns on a specific design or building location.)

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Where to Locate the WRB when using Continuous Insulation-Inside or Out?

This post first appeared on the Green Building Advisor Website.

Right now, there’s a lot of interest in the residential construction market around continuous insulation (CI) strategies.  CI adds a layer of complexity to a build, and with it, questions.  How much insulation do I need?  How to fasten the insulation?  How to fasten the cladding?  How to integrate windows and doors?  What about vapor control?  And, this question, should the water resistive barrier (WRB) be at the sheathing layer or outboard the insulation?  The answer, it depends, but you have a lot of choices.

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Construction Design-Interior Air Barrier? Exterior Air Barrier? Or Both!

When designing the concrete-less slab on grade home, I gave serious thought to the location of the air barrier.  I have used water resistive barrier (WRB) or house wraps for years without a good understanding how they work as an air barrier.  In my climate, most homes use polyethylene sheeting as an interior (and main) air barrier.  As it turns out, there are better choices. Continue reading “Construction Design-Interior Air Barrier? Exterior Air Barrier? Or Both!”