Sealing Around Replacement Windows: What Section 110.7 Requires
Yes. Section 110.7 requires every joint and opening in the envelope that can leak air to be caulked, gasketed, weatherstripped or otherwise sealed, and the compliance manual applies it to new and replacement windows. Where QII applies, gaps under 1 inch at jambs get minimally expansive foam. The window rating is a separate matter.
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Two leakage ideas, not one
A manufactured window must leak no more than 0.3 cfm per square foot of window area at 75 pascals, tested to NFRC 400 or ASTM E283 (Section 110.6(a)1). That is a property of the product. Section 110.7 concerns the joint between product and building: joints, penetrations and other openings that are potential sources of air leakage are to be sealed to limit infiltration and exfiltration. A window that carries a passing leakage label must still be sealed to the wall.
The remodel case
The manual's remodel example involves replaced windows and two added ones. Its answer says the new and replacement windows must meet the prescriptive U-factor and SHGC limits or be modeled, and must also comply with the mandatory caulking and sealing requirement of Section 110.7.
Windows built on site
Field-fabricated windows and exterior doors are caulked between the product and the building and weatherstripped. Unframed glass doors and fire doors are the only exceptions.
The QII detail for narrow gaps
Where Quality Insulation Installation applies, spaces under 1 inch wide at window and door jambs are filled with minimally expansive foam. If the window maker's warranty would be void with foam, the cavity must be airtight and filled with batt insulation cut to width, fitted snugly with limited compression. The appendix describes this foam as the handheld, single-component type used to seal gaps too small to insulate. An ECC-Rater checks conformance with Section 110.7 as part of the QII verification.
When the inspector looks
The manual places the rough-frame inspection after the windows are in and before insulation, to confirm that sealing and caulking around windows are finished. Seal first and insulate afterward. The 2025 manual's own air-leakage subsection for fenestration points back to the 2022 manual.
A job checklist is on window replacement, the single-window question is on replacing one window, label detail is on NFRC labels, and installers can start from the window installer page. See also residential 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
It is a code item. Section 110.7 is a mandatory requirement, and the manual states it applies to new and replacement windows.
The QII protocol names minimally expansive foam for gaps under 1 inch, with a batt alternative where the window warranty forbids foam.
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