New Construction HVAC Permits: Manual J, S, and D Requirements

In new construction, the HVAC design must be coordinated with the architectural and structural plans. Reliable Manual J load calculations require sufficiently developed, consistent construction information—including envelope assemblies, insulation levels, window types and sizes, ceiling heights, floor plan dimensions, orientations, and conditioned-space boundaries. A preliminary calculation can be prepared using documented assumptions, but changes to relevant construction inputs must be reviewed and may require recalculation before final design or permit submission.

Coordinating the design schedule with construction-plan development reduces the risk of revisions. Design work need not always wait until every architectural detail is finalized, but the calculation should reflect the construction information that will actually be built. If the HVAC design is ordered before the plans are sufficiently developed, the calculation may need to be revised when the plans change.

The design sequence follows the same order as any residential project: Manual J first, then Manual S, then Manual D. For new construction, each step must reflect the current plans and specifications. The design process may be iterative: equipment selection, airflow requirements, duct routing, and architectural constraints can require coordination and revisions across the three reports.

Manual J establishes room and building heating and cooling loads using the floor plan, room dimensions, construction details, window schedule, and local design conditions. Manual S evaluates equipment using applicable sizing criteria and appropriate model-specific performance information at relevant design conditions. Manual D designs supply and return ductwork using the selected equipment's airflow requirements, available static pressure, and duct layout. Manual D may not apply to a fully ductless system. Changes to any of these inputs after the design is prepared may require revisions to one or more of the reports.

Equipment selection for new construction should be coordinated before the permit is submitted where equipment details are required. Availability, approved indoor and outdoor unit combinations, manufacturer performance information, and installation requirements should be verified by the installing contractor and manufacturer. A substitution may require a new Manual S evaluation and, depending on the AHJ, revised permit documentation—but not every equipment substitution automatically requires a permit revision, and matching nominal tonnage alone does not establish equivalent performance.

Ask your contractor to confirm equipment availability and approved combinations before the permit is submitted. If the equipment selection changes after the permit is issued, share the proposed replacement model with the designer so the Manual S analysis can be reviewed for the new model. Confirm with the permit office whether revised documentation or updated permit approval is required. Savoy Engineering Group provides HVAC design services; it does not purchase, supply, install, or verify marketplace availability of equipment.

The Manual D duct design must reflect the proposed duct routing and selected equipment. The duct designer may develop the proposed duct routing using the architectural plans, equipment location, framing and structural constraints, available chases, and other project information. Manual D duct sizing and pressure-loss calculations must reflect the proposed design routing. Changes during construction that materially affect duct routing, fitting losses, or available space may require design review or revisions.

If the duct routing changes after the Manual D is prepared, the change should be reviewed before installation. Installed airflow and static pressure are verified by field measurements, not guaranteed by the Manual D report. Savoy Engineering Group provides duct design services; it does not perform duct installation or field inspection.

Plan changes are common in new construction. Window sizes, wall assemblies, room layouts, and equipment selections may all change between the initial design and the final permit submission. Each change that affects loads, equipment selection, airflow, or duct routing should be evaluated for its impact on the design.

Submit the documents currently required by the AHJ with the permit application. If the plans change after the permit is submitted, confirm with your permit office whether revised documentation or approval is required before proceeding with installation. Permit applicant eligibility varies by jurisdiction; eligible homeowners may apply where permitted under applicable local rules.

New construction HVAC permit requirements vary by jurisdiction. Some building departments require Manual J, S, and D for all new construction; others require only Manual J or a simplified energy compliance form. Ask your local building department which reports are required, what format is accepted, and when the documentation must be submitted. Adopted code requirements and the permit office's documentation checklist are related but distinct; the absence of a report-submission requirement does not necessarily eliminate an applicable code obligation.

Also ask whether the jurisdiction requires energy compliance documentation in addition to HVAC design reports. For typical residential projects governed by residential energy-code provisions, REScheck may be used where accepted by the AHJ. COMcheck generally addresses commercial energy-code compliance and is not an interchangeable alternative for a typical IRC residence. Energy-code compliance documentation and ACCA HVAC design reports address different requirements; acceptance of one does not automatically replace the other. REScheck is not required or accepted by every jurisdiction.