Methodology

Anyone can publish a cost range. Almost nobody says where it came from, which makes it impossible to check. This page explains how the numbers and claims on this site are produced.

Cost figures

Cost ranges are compiled from contractor-published price lists and quoted ranges current in the stated year, expressed per square foot of attic floor area unless noted otherwise. They are typical ranges, not quotes, and they carry the year they were gathered.

Regional labour rates move insulation pricing more than any other single factor, so a national range is a starting point for judging a quote, not a prediction of what you will be charged. Where a figure is an estimate rather than a published price, the page says so.

Technical and safety claims

We treat these as authoritative, in roughly this order:

• U.S. federal agencies: the Department of Energy, the Environmental Protection Agency, the Centers for Disease Control and Prevention, and the Occupational Safety and Health Administration
• Model codes and consensus standards, such as the International Energy Conservation Code and ASTM standards
• Manufacturer technical documentation, for product-specific properties
• Trade bodies, noted as trade sources

Where guidance is a judgement call rather than a rule, we say it is our view rather than presenting it as settled. Where requirements vary by state, we say that instead of generalising.

What we will not do

• We do not invent authors, credentials, certifications or awards.
• We do not publish reviews, ratings or testimonials, because we have no real ones.
• We do not present stock photography as our own work or crew.
• We do not claim experience or tenure the operating company does not have.

Reviews and corrections

Every page carries a "last reviewed" date, and it is a real date on which the page was checked rather than a timestamp that moves automatically.

If you find an error, tell us: [email protected]. We correct the page and, where the correction changes a reader's decision, we note what changed rather than quietly editing it.

An open limitation

Insulation pricing is regional and our ranges are national. We would rather publish the range with that caveat attached than publish a single confident number that is wrong nearly everywhere.