Sunroom Conversion Title 24 Requirements
An existing sunroom that becomes heated or cooled living space is newly conditioned space, so it is checked as an addition under Section 150.2(a). The glass decides the outcome: aging aluminum glazing is scored at default U-factor and SHGC values, and the walls and windows of the room count as new.
- Choose your report
- Upload your plans
- Pay securely
- Permit-ready report by email
What switches the rules on
A heater or cooler above the capacity thresholds in Section 100.1, or an opening that passes house air at more than three air changes an hour, makes the room conditioned. The unheated, door-separated case is on the sunroom page.
Old glass is scored at its default values
Unrated site-built glass within the area cap may use the default tables of Section 110.6 (Exception 5 to Section 150.1(c)3A), and the tables are unkind to old frames. A single-pane metal operable window defaults to U-1.28 and, for clear glass, SHGC 0.80, against prescriptive limits of 0.27 or 0.30 by zone. The manual adds that no default-table product meets the mandatory 0.40 weighted average on its own, so rated glass is needed unless an exception applies.
Panes reused from the house count as new windows, and existing walls around newly conditioned space count as new, so nothing earns credit for its age.
Which way each wall faces
West-facing means within 45 degrees of true west, including northwest and excluding southwest, so a glass wall on a northwest corner counts and one facing southwest does not. In climate zones 2, 4 and 6 to 15, an addition of 700 square feet or less may hold no more than 60 square feet of west-facing glass, with an SHGC of 0.23 (0.20 in zone 15). Zones 1, 3, 5 and 16 carry no SHGC limit in Table 150.1-A.
Where an SHGC limit applies, an exterior operable shading louver that achieves the same value is an accepted alternative. South-facing glass may instead use overhangs that fully shade it at solar noon on 21 August and expose it on 21 December (Section 150.1(c)4).
What the plan set should show
A window schedule listing each opening's frame, glazing, label or default value and compass direction, with sloped panes marked apart from vertical ones; sloped parts take skylight values (see skylight requirements). The same shell logic applies to an enclosed patio and a porch enclosure. Size limits are on room additions, and our residential reports start from your plans.
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
Only if its actual or default U-factor and SHGC pass, or the performance path absorbs the shortfall. The manual treats existing walls around newly conditioned space as new and a reused window as a new window, so old glass earns no credit.
No. Section 100.1 counts glass within 45 degrees of true west, including northwest, but excludes southwest.
Explore Additions and Remodels
- Does a Sunroom Need Title 24?
- Do I Need Title 24 for a Garage Conversion?
- Do I Need Title 24 for a Room Addition?
- Does a Bathroom Remodel Need Title 24?
- Does a Kitchen Remodel Need Title 24?
View all Additions and Remodels guides → · Permits and Compliance · Title 24 guide