About InsulationRValues.com

In one sentence

InsulationRValues.com is a sourced, homeowner-built reference for R-values, IECC code requirements, material costs, and the trade-offs between insulation choices — built so the next homeowner does not have to spend hundreds of hours digging through scattered sources.

Why this site exists

In 2022, I built my first house in North Dakota. That puts me in IECC Climate Zone 7 — winters where wind chill can drop below -40°F and a leaky building envelope means a furnace running half the day. With energy costs trending the way they were, I had one question: how do I build this once and not pay for it for the next forty years?

So I started reading. DOE energy guides. Oak Ridge National Laboratory whole-wall R-value studies. Building Science Corporation papers on rigid foam temperature performance. The 2021 IECC text and the state amendments that go with it. Manufacturer spec sheets. ASHRAE ventilation standards. RESNET installation-grade studies. Hundreds of hours across .gov and .edu PDFs and the corners of the internet where the people who actually install this stuff argue about the details.

What frustrated me was that nobody had pulled it together. Most existing insulation sites were contractor blogs trying to sell something, manufacturer pages promoting their own products, or thin AI content that didn't even have the climate zones right. The information existed — it was just scattered across thirty different places, and half of those places contradicted each other.

This site is the reference I built for myself, organised so you don't have to repeat the search.

What this site is

A research-based reference. Every R-value, code requirement, cost range, and recommendation here is sourced from primary documents — not scraped from other content sites. Numerical claims are cross-checked against at least two independent sources before publishing. Where sources disagree (polyiso's cold-weather derating is a good example), I say so instead of papering over it.

The calculators run on the same data tables I used to size my own envelope: 2021 IECC Table R402.1.3 for code minimums, Energy Star retrofit guidance for upgrade scenarios, and manufacturer R-per-inch ranges for thickness calculations.

What this site is not

I am not a licensed contractor, building scientist, or engineer. I built one house and read everything I could find from primary sources before making decisions. This site is educational reference material — not a substitute for professional advice on your specific project.

For local code compliance, structural questions, or moisture modelling on a specific assembly, hire a local pro. The Insulation Contractors Association of America contractor directory and your utility's energy-auditor list are good starting points.

How content is researched and updated

Primary sources first. DOE, ORNL, BSC, IECC, ASHRAE, manufacturer spec sheets. I avoid quoting other content sites as authority — they are usually citing the same primary sources you can read directly.
Cross-checked numbers. R-values, cost ranges, and code references are verified against at least two independent sources before publishing.
Dated articles. Each article carries a “last updated” date so you can tell when the underlying data was last checked. Year-stamps in headlines are only bumped when the article was genuinely re-checked.
Code revisions. When the IECC adopts a new edition or a state amendment changes requirements, affected pages are updated within 60 days.
Reader corrections. If you spot an error, email info@insulationrvalues.com. Errors that could affect a homeowner's decision get a published correction note on the affected article.

Sources used on this site

U.S. Department of Energy (DOE) — Energy efficiency guidance and insulation recommendations by climate zone
Oak Ridge National Laboratory (ORNL) — Building envelope research and whole-wall R-value data
Building Science Corporation (BSC) — Moisture management and building assembly research
International Energy Conservation Code (IECC) — Minimum R-value requirements by climate zone (currently 2021 IECC Table R402.1.3)
Energy Star — Retrofit guidance and program specifications
Manufacturer technical data — Owens Corning, Rockwool, Johns Manville, CertainTeed, Knauf, and others

Independence

InsulationRValues.com is not affiliated with any manufacturer, retailer, or installation company. No brand has paid for placement, and no manufacturer has reviewed or approved this content. Recommendations are based on building science data and cost-effectiveness — not commercial relationships.

How this site is supported

InsulationRValues.com is supported by display advertising (through Raptive) and affiliate links to retailers like Amazon, Home Depot, and Lowe's. If you click an affiliate link and buy something, the site earns a small commission at no extra cost to you.

Affiliate relationships do not influence recommendations. Many of the products I'd recommend (mineral wool batts in specific facings, certain rigid foam thicknesses, regional spray foam contractors) are not in any affiliate program at all. Where two materials would equally fit a given application, the choice is made on cost-per-R-value and installation constraints — not commission rates.

When content gets updated

When the IECC adopts a new edition or a state amendment changes requirements
When a manufacturer changes a published R-value or product specification
When new building science research changes the recommended approach for an assembly
When a reader reports an error that holds up under verification

Each article displays its last updated date. If you find an error or outdated information, please get in touch.

Get in touch

Questions, corrections, or partnership inquiries: plain email is the best way through. I aim to respond within two business days.

info@insulationrvalues.com