Do I Need Title 24 for a Garage Conversion?
Yes. Heating or cooling a garage creates newly conditioned space, which Section 100.1 says must meet the rules for an addition. A garage turned into a bedroom or den is not a new dwelling unit, so the whole-dwelling ventilation airflow an ADU needs is not required, and neither is solar PV.
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The trigger is conditioning
An unheated garage stays outside the envelope rules, though its lighting is still regulated (unconditioned space). Once a heater, air conditioner or mini-split above the Section 100.1 capacity thresholds serves it, it is newly conditioned space. The compliance manual lists converting a garage into living space as an addition, and so is permitting a conversion done years ago without one.
Rules that ease a conversion
- Where the old garage walls stay and the siding is not removed, they need cavity insulation of R-15 in 2x4 framing or R-21 in 2x6 framing, with no continuous insulation.
- Above 700 square feet, quality insulation installation need not cover headers over existing windows and doors, or air sealing where the air barrier stays. In the manual's example, a 400 square foot garage plus a 400 square foot bedroom above it makes 800 square feet: the old garage walls skip those two items, every new wall meets all of QII. At 700 or less, QII does not apply.
- Slab-edge insulation is asked for only in climate zone 16 (F-0.58, or R-7); in zones 1 to 15 a bare garage slab does not fail the prescriptive test.
- Solar PV is not required for an addition, and at 1,000 square feet or less neither is a whole-house fan.
Why it matters that it is not an ADU
Whole-dwelling mechanical ventilation is excused for an addition of 1,000 square feet or less that is not a new dwelling unit, so a family room or extra bedroom skips it. Make the same garage a garage conversion ADU and it becomes a new dwelling unit, with ventilation sized to that unit. Exhaust for any bathroom or kitchen applies either way.
What the report still has to cover
Glazing caps, attic insulation and radiant barrier apply as on any addition (room additions), and the glass or wall that replaces the garage door counts toward the glazing cap. The routes for documenting an addition are compared in the room addition question. Our residential reports start from your plans.
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
When its heating exceeds 10 Btu per hour per square foot or its cooling exceeds 5, as Section 100.1 defines directly conditioned space. A conditioned garage is then newly conditioned space.
No. Exception 6 to Section 150.2(a) says PV is not required for additions, which includes newly conditioned space.
Explore Additions and Remodels
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- Does a Bathroom Remodel Need Title 24?
- Does a Kitchen Remodel Need Title 24?
- 1,000 Sq Ft Addition Title 24 Requirements
- 300 Sq Ft Addition Title 24 Requirements
View all Additions and Remodels guides → · Permits and Compliance · Title 24 guide