Do Window Overhangs Help Title 24 Compliance?
Yes, for south-facing glass. Section 150.1(c)4D accepts an optimal overhang as the shading answer where Table 150.1-A sets a maximum SHGC: the glass must be fully shaded at solar noon on 21 August and substantially exposed to direct sunlight at solar noon on 21 December. East and west windows get little help.
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The test the code sets
The Standards define an overhang as a contiguous opaque surface, oriented horizontally and projecting outward from an exterior vertical surface. A vertical fin is a separate thing. South-facing means within 45 degrees of true south. The overhang test is written as a result on two dates, so the depth that passes depends on how high the overhang sits above the glass and where the building is.
Where it applies
Section 150.1(c)4 applies only where Table 150.1-A requires a maximum SHGC: zones 2, 4 and 6 to 15. Zones 1, 3, 5 and 16 have no SHGC requirement for an overhang to satisfy. Section 150.2(b)1B sends replacement windows to the same shading section, so the option is open to a replacement south window.
It has to be permanent
Exterior shading devices must be secured with attachments or fasteners not intended for removal. The exception is where the California Building Code requires emergency egress or compliance would conflict with health and safety rules.
In a performance run
For a new home the standard design is modelled with no overhangs, so a real one is credit. Overhangs and side fins attached to the building, and shading from the building itself, count. Trees, neighbouring buildings and terrain do not.
Not a fix for east and west
The 2022 manual explains that late sun is low, so overhangs do little on east and west faces; vertical fins can help but cost view and light. Cooling-climate designers are advised to cut glass on those sides instead, covered on window orientation.
A fixed overhang is only one option; exterior shading credit covers screens and awnings. Window numbers are on U-factor vs SHGC and new windows and Title 24. Our residential reports model overhang depths.
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
For south-facing glass, yes: Section 150.1(c)4D lists an optimal overhang as one way to meet the shading requirement where Table 150.1-A sets a maximum SHGC.
No. The manual gives no compliance credit for shade from trees, adjacent buildings or terrain.
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