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12 Answers

ZIP system R-sheathing on a Roof

I'm looking for a poor-man's alternative to thick polyiso on a roof and was wondering why ZIP system R-sheathing is not "allowed" to be on a roof? From Huber's web site:

"Zip System R‐Sheathing is currently limited to wood‐framed wall applications only. DO NOT use roofs or light gauge metal framing. For systems requiring multiple layers of water‐resistive barriers, ZIP System R‐Sheathing is intended to replace only the first."

My roof is extremely unique and you will all probably roll your eyes, but here we go:

1. My Roof is vented with baffles

Asked By Christiaan Lutzer | Sep 20 16
6 Answers

Low-e? "Do not scrape glass."

I just installed some high end french doors that came with a sticker warning 'DO NOT SCRAPE GLASS". Does anyone know anything about this? Is it some new kind of low E film, have there been long term problems with scraping low E glass?

Asked By William Goodwin | Sep 24 16
35 Answers

Have many questions about HVAC, insulation, and ventilation

I have many questions about HVAC, insulation and ventilation, but will just start with a few. If we decide on an exhaust-only system for a new build home, does also trying to button up the envelope tight work with that type of ventilation?

We will probably insulate with fiberglass blown in at attic floor because spray foaming the whole attic would be so much more expensive. If we don't insulate at roof, do we need to install a radiant barrier at some location to try to bring the heat down in attic?


Asked By C Clark | Sep 21 16
7 Answers

Air sealing

I am in the process of building a new home in zone 5. We are doing a passive solar house with vaulted ceiling in the living room, kitchen and dining room area and the rest of the house will be flat ceilings. I plan to do blown in cellulose insulation on the flat ceilings and closed cell on the vaulted ceiling. I plan to do 3” of rigid foam insulation on the exterior walls with spary in cellulose (2x6) walls. I am also using Prosoco seam filler for the sheathing and Fast Flash for the flashing.

Asked By Michael Brackett | Sep 23 16
1 Answer

Sheet metal over interior studs: Mold issue?

I'm a homeowner / GC who's building a custom home. We're using 1 1/2" Roxul for exterior insulation, 1" closed cell foam on the interior seathing, and cellulose in the remaining 2 x 6 stud cavities.

Asked By Ryan Lazuka | Sep 23 16
7 Answers

Best insulation method for LP Smartside panels as sheathing & siding?

Building woodshop in cold climate...zone 6-7. Using LP Smart side panels as sheathing and the siding. 190 series, product is .53" thick.

Concerned about condensation on interior side of this sheathing/siding in cold weather. Will dense pack cellulose be fine, or should this siding/sheathing be first sprayed with 2lb closed cell foam?

Asked By eric Mikkelsen | Sep 4 16
2 Answers

Wood wool cement acoustic panels in North America?

I came across an interesting product for acoustic control: wood wool + cement panels.

They have a great look:


but the only suppliers I've been able to find are Scandanavian:


Since it seems to just be wood + cement, I was wondering if there are any US or Canadian suppliers.
I'm outside of Portland, OR, and don't like the idea of shipping a container of wood across the world = )

Asked By Kevin Lynagh | Sep 23 16
5 Answers

Is it possible to satisfactorily detail single layer of exterior xps square edge sheathing?

Having been directed to an insulation reclaimer I have the opportunity to purchase enough reclaimed xps to sheath my exterior frame though only with a single layer since the 2.5" panel thickness satisfies my requirement. Timberframe has a 2x5 (full dimension) exterior frame that gets cellulose densepack and sheathed with xps that will get 1x4 strapping prior to siding. This foam is square edge and I'm wondering if, in the absence of multiple layers with staggered seams as well as t+g edges, the detailing to adequately seal the seams of the xps will be possible or even approachable.

Asked By daniel f. vellone | Sep 23 16
6 Answers

Why is mold/mildew growing behind my rigid foam?

So I had started to finish my basement area and read all of the articles on GBA. I was using 2'' of XPS foam on the cinder block walls and recently had to remove a bunch to access an area for the egress window. When I pulled it off, I was surprised and scared to see that I had black stuff growing on the cinder block. I don't know if it's mold or mildew, but it can't be good, right? You can even see how it's growing around the foam adhesive that I used to attach it to the wall.

Asked By Jay Johnson | Sep 21 16
7 Answers

Fiberglass insulation

I read your article on insulation an older home that does not have sheathing behind the ceder lap siding. The house is in southern Missouri so I was planning on 0.75 inch foiled rigid foam board (foil facing the exterior siding with a 0.75 inch air space. My question is should the fiberglass batting have kraft paper or just the fiberglass batting. I was planning on 0.5 inch sheet rock for the interior walls.

Thank you for your time.


Asked By Jim Tune | Sep 6 16
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