Exposed Zip R Edge Detail
jimgove30
| Posted in General Questions on
Hi all,
We have our Zip R9 installed now, and I was curious what the plan was to detail the edge of the foam to the concrete foundation wall (there is no detail specified in the plans). When I asked the builder, they responded very confidently that they just leave it open. Always do, and haven’t had any issues.
When I brought up that there are options like ripped lumber, mesh screen, or perforated metal options they said they were curious, and willing to explore options, but I guess it leaves me wondering, is this a regional thing? We’re NH zone 6. Am I asking for problems if I skip it?
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Huber's website has a details library for the zip r products. There are a lot of good suggestions there. You can also check with your local Huber rep,you can search for this on their site as well. I can't imagine leaving OSB exposed like that would be a good idea or recommended by the manufacturer.
I checked out the tech library. What a great resource. I downloaded a couple details and will send them to the builder. There are a couple solutions in there such as the flashing Malcolm mentions below. Appreciate the tips, guys.
jimgove30,
What's the plan for the area in-between the Zip-R and the rigid insulation below? That may inform how you handle the bottom.
Hi Malcolm,
I believe the two materials were never planned to meet. In fact, I don't see the zip R shown on the plans to cover down that far and cover the rim, but they did that anyway.
Jimgove30,
It sounds like there is some confusion on your drawings about how to maintain the continuity of your insulation. I can't see how it makes sense to have the Zip not extend over the rim-joists unless the area was intended to be insulated on the interior - which then begs the question as to why there is exterior foam below.
If the exterior foam stops below grade, the exposed portion of concrete between it and the framing above will act as a thermal bridge, making that insulation largely useless. I would consider filling in that gap, which is a bit complicated because it involves providing some mechanical protection for that new foam. Extending that protection down below grade to prevent insect damage is something I'd also think about doing.
The blue foam on the outside of the foundation is really only there as a drainage plane. Honestly, the basement was an afterthought, as we had planned a SOG. I had no idea that blue foam was even going to be there.
My intent is to insulate on the inside of the basement walls, with rigid foam (Thermax maybe, TBD), and since the zip R covers the rim, mineral wool batt the inside of the rim. From there, we'll finish the basement space later (bleeding $$$$$).
jimgove30,
Great. One less thing to worry about!
So back to your original question: I wouldn't leave it. Any self-respecting rodent can be into your wall cavities in a couple of minutes the way it is. Because the Zip extends down onto the concrete, the only nailing surface is the OSB, which precludes some options. Probably the easiest solution is a piece of U-shaped or L-shaped flashing. Use Zip tape to seal it to the OSB.
Ok, makes perfect sense to me! Thank you.
Jim,
Take a look at this thread:
https://www.greenbuildingadvisor.com/question/outsulation-and-rain-screen