The Grandfathered Split-Level: Addition, Window Swap, and Opened Walls
A single permit is issued for a 1,960 ft² split-level built in 1968 in Climate Zone 4A. The scope: a 400 ft² conditioned family-room addition with five new windows and one sliding glass door; replacement of 11 existing windows in the original house; and re-piping that will open about 700 ft² of exterior wall cavity (2×4, currently uninsulated) before drywall goes back. The addition's supply ducts run through the vented attic. At final inspection the inspector finds: no insulation certificate posted, a sliding door supported only by a color brochure claiming 'energy-efficient glass,' no duct leakage report, and one opened wall cavity already closed with no insulation. The contractor argues that the old house is 'grandfathered' and that the brochure is 'the manufacturer's rating.'
1. Which parts of this project must comply with the residential energy provisions, and which may be left as they are? Give the scope logic, not just a conclusion.
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Reasoning: The existing-buildings chapter organizes requirements by type of work, not by building size.
- Addition (400 ft²): treated as new construction. Its envelope, fenestration, duct insulation and duct sealing, and any mechanical equipment serving it must meet Chapter 4 for Climate Zone 4. There is no obligation to upgrade the unaltered 1968 portion to today's R-values.
- Replacement windows (11): this is an alteration of a building component; the replacement fenestration is the altered element and must meet the zone's fenestration U-factor. The fact that the originals were single-pane does not create a pass.
- Opened wall cavities (700 ft²): re-piping is not, by itself, a trigger to add cavity insulation. The governing principle is that the altered building must not be left more noncompliant than it was, and that the thermal boundary and air barrier must be restored where disturbed. Closing an uninsulated cavity that was uninsulated before is generally not a violation; leaving an unsealed air path or a missing vapor retarder where one is required is.
- Unchanged remainder of the house: grandfathered - no mandatory retrofit.
Judgment point: "grandfathered" is a valid defense for the untouched house and an invalid defense for the addition, the new windows, and the altered assemblies.
2. The sliding door in the addition has no NFRC label, only a manufacturer brochure that says 'energy-efficient glass.' How does the code official resolve compliance, and what are the builder's real options?
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Reasoning: Fenestration compliance is proven by a rating, not by marketing language. The code makes NFRC 100/200 (or an approved equivalent) the basis for U-factor and SHGC, and it supplies a default fenestration table for units that carry no label or certified rating.
- Absent a label, the official applies the default table. Those defaults are deliberately conservative; for ordinary frame types they land above the Climate Zone 4 maximum, so the door fails on paper.
- The official may also demand evidence of the rating - a certified rating report or an approved alternative method - and is not required to accept a spec sheet.
- Builder's options: (a) produce the NFRC label/certified rating for that specific model and glazing package; (b) substitute a compliant unit; or (c) resubmit the whole project under a performance/total-UA path in which the door's penalty is actually modeled against other envelope improvements.
What is not an option: trading the door against the attic insulation under the prescriptive path. Component-by-component compliance has no self-help trade, and a single door cannot be swapped in isolation.
3. What must exist before the final inspection can be approved, and does the uninsulated closed cavity by itself block approval?
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Reasoning: Distinguish mandatory construction documents from discretionary upgrades.
Required documentation:
- The permanent insulation and fenestration certificate, posted in the building, listing ceiling/wall/floor R-values, fenestration U-factors and SHGC, and mechanical equipment efficiencies. This is a code-required document, not paperwork the builder can mail later.
- Duct leakage test results for the addition's attic ducts (ducts outside the conditioned envelope are not exempt), reported in cfm per 100 ft² of conditioned floor area.
- Envelope leakage test results if testing is required in the adopted edition, plus mechanical ventilation documentation.
The closed uninsulated cavity: by itself it does not fail the alteration, because the assembly was uninsulated before and the code does not mandate a retrofit. It does fail if (a) the permit documents or a performance submittal claimed the insulation as a compliance credit, or (b) the air barrier at that cavity was not restored and shows up in the blower-door result.
Approval logic: hold the final on the certificate, the duct test, and the unlabeled door - not on the grandfathered wall.