Attic Insulation Certificate: What the Contractor Must Give You

The written certification in an existing attic

Section 110.8(d) covers insulation installed in an existing attic, or on an existing duct or water heater. If a contractor does the work, the contractor "shall certify to the customer, in writing, that the insulation meets the applicable requirements". For an attic the requirement is the R-value: the total after the new material is added to what was already there must satisfy Section 150.0(a). The text names no form and no wording, so ask for a signed statement giving the finished R-value.

One exception to the R-value

If the accessible attic space is too small to hold the required depth, the contractor fills the entire accessible space instead. That works only if it does not violate the Building Code's attic ventilation sections.

What the product itself must carry

• All insulation is certified by the Department of Consumer Affairs, Bureau of Household Goods and Services, under the state standard for insulating material.
• Loose-fill must be installed at the manufacturer's design weight per square foot for its labeled R-value, which is why the bag label or coverage chart matters.

The extra paper under QII

QII covers new homes and additions over 700 square feet, not a typical attic top-up. There the installer signs the certificate to say the work matches the Certificate of Compliance, plans and specifications. For loose-fill the bag label or coverage chart for each product is attached, showing minimum installed weight per square foot and inches needed. For batts and board the attachment is the product data sheet. Both must be on the job site at each ECC-Rater verification, and the appendix says the rater cannot give credit without the completed forms.

What to ask for before final payment

Keep the signed written certification and the bag label or data sheet together. They answer a plan checker later.

Technical triggers are on attic insulation for remodels. The QII checks are on the QII attic page and the QII overview. For unknown existing insulation, see older homes. Form numbers are in Title 24 forms. See also our residential reports.

Common Title 24 Questions

1. When is Title 24 required for a home?
2. Does a remodel need Title 24?
3. Does a room addition need Title 24?
4. What plans are needed for a residential Title 24 report?
5. How much does a residential Title 24 report cost?
6. How long does a residential Title 24 report take?

Frequently Asked Questions

Does the certification have to be on a state form?

Who gets the bag label?

Explore Insulation

1. Attic Insulation Requirements for California Remodels
2. Can a Radiant Barrier Replace Attic Insulation Under Title 24?
3. Cathedral Ceiling Insulation Under the 2025 Energy Code
4. Crawl Space Insulation Requirements Under Title 24
5. Is a Blower Door Test Required in California? Title 24 Air Leakage Testing

View all Insulation guides → · Windows and Building Envelope · Title 24 guide