Comments on: Is Wind Washing Reducing Your Insulation R-Value?

By: MJ

MJ — Wed, 19 Oct 2022 01:56:46 +0000

The cardboard baffles in the 5th photo make me nervous. Wouldn’t that just be opening the door (so to speak) for mold growth? (Say, in a humid climate, even if you were able to keep other sources of moisture from the attic?).

By: Scott

Scott — Tue, 18 Oct 2022 10:53:43 +0000

In reply to Paul Szymkiewicz. Any Fiberglas insulation should always be used inside the air barrier. Any air moving through Fiberglas reduces the r value to what, almost zero?

By: Garnet Funk

Garnet Funk — Tue, 18 Oct 2022 01:20:43 +0000

I’ve experienced these scenarios and come to realize that in the old days we had 1/4″ plywood soffits with a 6×12 inch vent every 8 ft with substantially less air flow Bad and Good
Now with perforated aluminum the standard soffit a gigaton of air is blowing thru I now use non perforated over front door canopies and rear deck large roof over unheated deck areas and have raised truss heel heights to 18 ” with solid osb panel tightly fastenened also double anchor system truss to pane to top plate Done Fixed no more crappy cardboard chutes or flimsy sm stops As a framer this is my preferred solution

By: Allison Bailes

Allison Bailes — Thu, 13 Oct 2022 20:12:12 +0000

In reply to Matt. Matt: Yes, you could install a radiant barrier to prevent wind washing, but that's not what it's made for. Radiant barriers don't save a whole lot of energy in new homes, but they do keep the attic cooler, which anyone who goes up there in summer will appreciate. If you're laying down on top of the insulation, you could be turning the radiant barrier into a condensing surface, even with the perforations. Depending on how cold your climate is, that could make a mess of the insulation and your ceiling in winter. And then there's the dirt issue. It won't take long for a radiant barrier lying on top of the insulation to get dirty, which will greatly reduce its reflectivity and increase its emissivity. And a low-e material without low-e doesn't do much.

By: Tammi Stevenson

Tammi Stevenson — Thu, 13 Oct 2022 20:03:58 +0000

In reply to David. In the top of my garage I used 1 inch spacers for air circulation and cut 1 inch x2 ftx 8 ft styrfoam with a reflective side and put it between the trusses then sprayfoamed all edges. Then rock wool insulation bats over that. Was a lot of work but glad i did it. Toasty warm and no drafts.

By: Matt

Matt — Thu, 13 Oct 2022 14:04:48 +0000

In reply to David. I think it would work well for most insulation applications except for spray foam, polyiso, etc, where it wouldn’t be necessary. You can check out their product at atticfoil.com. It is much better than other radiant barrier products out there. It is designed to lay right on top of the insulation, keeping the heat (or cold) in and letting the moisture out.

By: Thomas Dugan

Thomas Dugan — Thu, 13 Oct 2022 12:40:11 +0000

I would like to submit another possible issue with wind washing. Humidity. I build on coastal NC where humidity is a big concern. Air infiltration carries with it air suspended moisture that can reach dew point when it comes in contact with our cool air-conditioned spaces. As with almost any infiltration, this condensation can be anywhere in the building envelope. The result is nice warm damp surfaces that are prime candidates for mold. Completely out of sight and in places we cannot get to. Yet I still have arguments with other builders regarding this whole “the house has to breath” nonsense.

By: David

David — Thu, 13 Oct 2022 12:20:50 +0000

In reply to Matt Philleo. Matt, Does the attic foil look suitable for retrofits in a 50 year old house with r-38 of blown in loose fill?

By: David

David — Thu, 13 Oct 2022 12:15:08 +0000

In reply to Allison Bailes. Thanks, I’m replacing the entire system in a few weeks. I’m having a full test after it’s completed including a blower door test. We will see if I can finally fix that hidden leak. Insisting on the best practices if learned hear and with the building sciences corp blog, I ended up disqualifying over 50% of the proposals and an additional 34% recalls their bids. Because of the common expected standards explained here were to burdensome or beyond the contractors comprehension. Is a sad commentary on the state of the industry that they can’t, won’t, or doubt know how to follow current standards.

By: Matt Philleo

Matt Philleo — Thu, 13 Oct 2022 04:07:53 +0000

Interesting article. I recently added R-55 insulation to the attic of my studio building. I purchased something called attic foil which is basically house wrap sandwiched between two layers of aluminum foil. It also has many noticeable perforations designed to allow moisture to escape. But it prevents convective currents and possibly wind washing too. I am very happy with it. The insulation is nice and dry and I know it’s doing it’s job.