700 Sq Ft Addition Title 24 Requirements
At 700 square feet an addition is still on the lighter package: no quality insulation installation, a 60 square foot west glazing cap and a plain R-38 or R-30 attic. At 701 it moves to the new-home package, with QII, 70 square feet of west glazing and a choice between two attic routes.
- Choose your report
- Upload your plans
- Pay securely
- Permit-ready report by email
What flips between 700 and 701
- Quality insulation installation (QII) becomes prescriptive. An ECC-Rater verifies the air barrier and insulation, so the certificate is registered with an ECC-Provider before it goes to the building department.
- West-facing glazing rises from 60 square feet to the greater of 70 square feet or 5 percent of floor area.
- The attic gets two routes. Option B adds below-deck insulation, R-19 in zones 4 and 8 to 16, and allows ducts in the attic. Option C puts the air handler and ducts in conditioned space and lowers ceiling insulation to R-30 in zones 2 to 7.
What does not flip
Total glazing barely moves. Twenty-five percent of 700 is 175, and above 700 the cap is the greater of 175 square feet or 20 percent, so 175 holds on both sides until 875 square feet, where 20 percent takes over. Extended walls still keep R-15 or R-21, and the ventilation exemptions run to 1,000.
Count every piece under the permit
Separate additions under one permit add together to set the tier. A 400 square foot garage conversion plus a 301 square foot bedroom is 701 square feet and takes QII, though the converted garage's existing walls may skip header insulation and air sealing when the air barrier stays. Every new wall meets all of QII.
Choosing the route near the line
Modeling the existing house with the addition sets the addition's budget from the same tier under Section 150.2(a)2B. QII is not mandatory in performance modeling, but the software assumes it in the standard design and reduces the credited insulation when it is not pursued. A design at 710 square feet can trim 10 square feet to stay on the lighter package, or keep them and plan for quality insulation installation from framing stage.
The tier below is on the 500 square foot addition page and the next line up on the 1,000 square foot addition page. See also room additions, the CF1R and our residential service.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
No. Section 150.2(a)1Bv says the QII requirement of Section 150.1(c)1E does not apply to additions of 700 square feet or less. At 701 square feet it applies, with an ECC-Rater verifying the work.
For the prescriptive tier, yes. The manual says the total floor area of an addition may include several separate additions under the same permit.
Explore Additions and Remodels
- Addition Over 1,000 Sq Ft: Title 24 Requirements
- Basement Conversion Title 24 Requirements in California
- Does a Basement Conversion Need Title 24?
- Bathroom Remodel: When Title 24 Is Triggered
- Bonus Room Over a Garage: Title 24 Requirements
View all Additions and Remodels guides → · Permits and Compliance · Title 24 guide