Are structural sheathings with build in weather barriers and insulation good?

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Combo structural sheathing, WRB and thin insulation panel in Ontario?

Steve Bull Published: Jan. 14, 2020, 6:06 p.m.Last updated: Sept. 4, 2020, 1:23 p.m.

Hi: I am stripping a 150 yr old timber of its 3 layers of siding and re-insulating and leak-sealing the exposed cavities from the outside. I will be re-sheathing it, and double strapping it for a rear-vented vertical board and batten exterior.

My research into potential sheathing has turned up a couple innovative products that combine a 1"- 1 1/4" structural panel, with an R4-R5 foam component, and a water-resistive barrier coating or layer incorporated into it, eliminating the need for an additional house-wrap: Barricade Thermo Brace, and BP's R4-HP panel.

These initially appealed to me due 1) their light weight (I am working alone on a multi-story), 2) the additional R-value to combat any thermal bridging, and 3) the elimination of the time and cost associated with a house-wrap.

However I am unable to locate any retail sources in Ontario or any information on the real-world experience of installing and living with these products, short of reading the always rosy manufacturer's claims. I am usually leary of "all-in-one" products but these seem like they could be the real deal. Although Barricade has some products north of the border, the panels don't make the trip. Similarly, BP's panels don't make across the Quebec border into Ontario, and are unavailable through RONA, despite being on their web-page. An e-mail reach-out by me to BP has gone unanswered. I am wondering if there may be a provincial roadblock to their sale in that they possibly don't meet code, at least in terms of being a structural panel.

Particular to my installation, and my timber-frame with non-standard (or non-existant) stud-spacing, I am also wondering if these panels are meant specifically for new construction with 16" OC and if I'll need to supplement with some additional studs for support.

Any information on these products, or something similar that I haven't found, and their availability would be most welcome.

Steve

Responses (3)

RJ @ecohome.net Feb. 10, 2020, 2:54 p.m. Reply

Judging by your well-written response, I think you have a pretty good handle on this Steve. Doing an air barrier room by room from the inside is indeed, something of an exercise in futility. So for sure you will have greater success working from the outside if you can.  And as you mention, there’s no sense tempting fate - EPS with perforated foil is going to be more breathable than say, EPS with un-perforated foil, but a breathable house wrap and Rockwool is still a safer route. 

I wouldn’t worry about tightening it up too much, I would go for it and then if its nice and airtight you can then put in an HRV. The only way to really determine that is to do a blower door test, that will cost you a few hundred bucks probably but it will give you the answers you need. And if you do it after you install your exterior air barrier but before you install siding, you can use it as a tool for finding any remaining leaks. 
If you end up needing an HRV, you may not be too excited about running ducts all around the house, in which case you might be a candidate for a ductless wall-insert HRV