Porch Enclosure Title 24 Requirements
A porch enclosure is an addition, and the compliance manual works one through: a 75 square foot porch in climate zone 7 needs R-30 ceiling insulation with a radiant barrier, R-19 under the floor and R-15 in extended walls. Other zones change several numbers, so read the example as a pattern rather than a promise.
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The manual's own porch
Example 9-9 encloses a 75 square foot porch in zone 7 by extending existing 2x4 walls, served by existing heating and cooling with under 25 feet of new duct. The prescriptive answer:
- Glass is capped at 75 square feet in total and 60 square feet facing west, with a U-factor of 0.30 and an SHGC of 0.23 or lower.
- The ceiling takes R-30 with a radiant barrier in a ventilated attic, and the floor takes R-19.
- Extended 2x4 walls need only R-15. A wall that is not an extension must reach U-0.065, which R-15 plus R-4 continuous insulation in 2x4 framing does.
- No cool-roof product is needed because the addition is under 300 square feet.
- Existing equipment need not meet efficiency rules, but the duct system is sealed and tested to 10 percent total leakage or 7 percent to outside, and new ducts in unconditioned space take at least R-6.
What shifts outside zone 7
In zones 1, 2, 4 and 8 to 16 the ceiling goes to R-38 and new ducts in unconditioned space to R-8 (Table 150.2-D). Walls that are not extensions take U-0.048 in every zone except 6 and 7. For an addition this small, window U-factor is 0.27 in zones 1 to 5, 11 to 14 and 16, and 0.30 in zones 6 to 10 and 15.
The floor is the porch-specific item
Many porches sit on raised wood framing over open air or a crawl space. A raised floor between conditioned space and unconditioned space or ambient air takes U-0.037 (R-19 in wood framing) in every zone. The exception to Section 150.0(d) lets an unvented or controlled-ventilation crawl space omit it, but only when its foundation walls, vapor retarder and vents meet listed conditions. A porch on a slab follows the slab-edge rule.
An unheated screened porch
With no heating or cooling and weatherstripped doors to the house, the porch stays unconditioned and only its lighting is regulated. See patio enclosures, sunroom conversions, room additions and our residential Title 24 reports.
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. It is a climate zone 7 case. Other zones change the ceiling, wall, glass and duct values, so a report uses the values for the project's own zone.
Because many porches are raised. A raised floor over unconditioned space or open air is an envelope surface and takes R-19 or U-0.037.
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