The Square Footage Changed After the CF1R: Do I Need a New Report?
Often, yes. Five size lines matter for an addition: 300, 400, 500, 700 and 1,000 square feet of conditioned floor area. Cross one and the roofing rule, glazing limits, water heater options or even the CF1R form can change. A shift inside one band may not, so ask the department before you build the extra foot.
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Why the total, not the drawing, drives the report
The manual measures the conditioned floor area of the addition and adds up separate additions built under one permit. Only conditioned space counts: the code defines an addition as a change that increases both conditioned floor area and conditioned volume, so an enclosed porch that becomes heated is an addition and an open deck is not.
What changes at each line
- 300: additions of 300 square feet or less skip the roofing product rule, and below 300 a department may simplify certificates when no field verification applies.
- 400 and 700: the glazing allowance steps from the greater of 75 square feet or 30 percent of the addition, to 120 or 25 percent, to 175 or 20 percent above 700. Prescriptive quality insulation installation applies only above 700.
- 500: an additional water heater may be an electric unit with point-of-use distribution only up to 500 square feet.
- 1,000: the prescriptive form switches from CF1R-ADD-01-E to CF1R-NCB-01-E (the manual's table puts exactly 1,000 on the NCB side), and whole-dwelling ventilation airflow applies above a 1,000 square foot increase.
A change that stays inside its band
Growing a 520 square foot room to 560 keeps the same rule set, but the glazing allowance is worked out from the area, so certificate and plans must still agree. Section 10-103(a)2B asks whether the change may leave the building out of compliance; if it may, amended plans and certificates go to the department. If unsure, send the revised floor plan and ask.
What happens to registered documents
A revised registered CF1R is signed again with a higher revision digit. The old version becomes obsolete, and any registered CF2R that depends on it must be signed again. Registration applies when an ECC-Rater verifies part of the job; see what registration required means.
Before the extra foot is framed
The size pages explain each band: 300 square feet, 700 square feet and over 1,000. For late design edits in general see architect changes and the amended CF1R quick reference; our residential reports are re-run on the revised set.
Common Title 24 Questions
- What is Title 24?
- Do I need a Title 24 report?
- How much does a Title 24 report cost?
- How long does a Title 24 report take?
- What is included in a Title 24 report?
- What plans do I need to upload?
Frequently Asked Questions
The built size has to match what the certificate states. Shrinking may move you into a lighter band, but the department decides under Section 10-103(a)2B whether it wants amended documents.
Yes, once it is conditioned. The manual treats a 75 square foot enclosed porch as an addition, while space that stays unconditioned adds no conditioned floor area.
Explore Title 24 Revisions
- Title 24 for a Permit Revision After Plan Check
- What Happens If the Architect Changes the Plans After Title 24?
- What Happens If the Contractor Installs Different Equipment Than the CF1R?
- Which Field Changes Need an Amended CF1R? A Quick Reference
- Changed HVAC After the CF1R: What to Do
View all Title 24 Revisions guides → · Permits and Compliance · Title 24 guide