Wyoming Attic Insulation R-Value Guide (Code Minimums + What Actually Works)
Wyoming attic insulation code minimum is R-49 (Climate Zones 6 and 7), which works out to roughly 14 inches of fiberglass batt, 13 inches of blown cellulose, 13 inches of open-cell spray foam, or 7 inches of closed-cell. Going higher pays back in 4 to 7 years on most Wyoming homes.
This guide answers the question we get most often after a winter storm: "What R-value does my attic actually need in Wyoming, and how do I get there?"
Wyoming code minimums
Almost all of Wyoming is IECC Climate Zone 6 or 7. The 2021 IECC sets attic insulation minimums at:
- Climate Zone 6 (most of WY): R-49 attic
- Climate Zone 7 (higher elevations, NW WY): R-49 attic — but practically, you want R-60
That is a minimum. It is the line a new build has to clear. If your house was built before 2009 you are almost certainly under it.
What R-49 looks like in real materials
| Material | R per inch | Inches to hit R-49 |
|---|---|---|
| Fiberglass batt | ~3.5 | ~14" |
| Blown cellulose | ~3.7 | ~13" |
| Open-cell spray foam | ~3.7 | ~13" |
| Closed-cell spray foam | ~7.0 | ~7" |
The catch with batt and blown insulation
Those R-values are lab values. In a real Wyoming attic, wind blows under and around batts, compresses them, and short-circuits the insulation around can lights and bath fans. Studies have shown effective R-value drops by 20% to 40% in real installations. That is "wind washing" and it is brutal in this state.
Spray foam does not wind-wash. The cavity is sealed, full-stop.
The unvented attic option
The other path is to spray-foam the underside of the roof deck and turn the attic into "conditioned" space. We covered this in detail in our attic insulation service page and energy savings post. Short version: in Wyoming, sealing the roof line with closed-cell foam eliminates ice damming, brings HVAC ducts into the conditioned envelope, and typically cuts heating bills 25–40%.
When to go higher than code
If you heat with electric (resistance or heat pump) anywhere in Wyoming, push to R-60 minimum and consider R-70. Marginal cost is small; marginal savings compound for 30 years.
If you have an attached garage with bonus space above, treat it like a Climate Zone 7 attic regardless of zoning — that ceiling-floor is your weakest link.
How to diagnose your current attic
Stick a ruler in your attic insulation. Multiply inches by the R-per-inch in the table above. If the answer is under R-30, you are bleeding money. Free attic inspections from us include a depth check and a thermal scan in cold weather. Schedule an inspection.
For sub-service detail, see unvented attic spray foam and closed-cell spray foam.
Questions we get most.
How do you quote a spray foam job?
We do not publish a public price list. Every spray foam quote is tailored after a free on-site inspection — we measure the area, confirm open-cell vs closed-cell, and pick the thickness that hits the R-value you actually need. Use the spray foam calculator on the site to send us your specs and we will email a quote the same day.
How do you quote a new garage door install in Wyoming?
Every install is quoted after a free on-site visit so the number matches the actual scope — size, insulation grade, opener, and whether we are hauling off an old door. Use the garage door calculator on the site to send us your specs and we will email back a tailored quote the same day.
Are you licensed and insured?
Yes. Seamless Systems LLC is a licensed and insured Wyoming home services company, founded in 2016 by Cody Williamson with over 25 years of combined crew experience in garage doors, gutters, and spray-foam insulation.
What is the difference between open-cell and closed-cell spray foam?
Open-cell foam is softer, lighter, has an R-value of about 3.5 per inch, and is great for sound dampening in interior walls and roof decks. Closed-cell foam is denser, has an R-value of about 7 per inch, adds a vapor barrier, and increases structural rigidity — common in our region for unconditioned shops, metal buildings, and exposed crawl spaces.
