Rescheck vs Manual J vs Comcheck —
What Do You Need for Your Building Permit?

 

If you're applying for a building permit, you've probably heard terms like REScheck, Manual J, or COMcheck — but knowing which one you actually need can be confusing.

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Each serves a different purpose in energy code compliance and HVAC sizing. This guide explains the differences clearly so you can determine exactly what your project requires.

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What Is a Rescheck Energy Report?

A REScheck energy report is a compliance document used to show that a residential construction project meets the requirements of the International Energy Conservation Code (IECC).

 

It evaluates the building envelope, including:

• Insulation values

• Window performance

• Door specifications

• Roof and wall assemblies

 

REScheck is commonly required for:

• New home construction

• Room additions

• Major remodels affecting insulation or windows

• Garage conversions to living space

 

Most residential building departments require proof of energy code compliance before issuing a permit — and REScheck provides that documentation.

 

What Is a Manual J Load Calculation?

A Manual J load calculation is an ACCA-approved method used to determine the proper heating and cooling capacity required for a home.

It analyzes:

• Square footage

• Climate zone

• Insulation levels

• Window orientation and performance

• Air infiltration

• Ceiling heights

 

Manual J ensures HVAC equipment is properly sized. Oversized systems short cycle and waste energy. Undersized systems struggle to maintain comfort.

 

Manual J is commonly required for:

• New HVAC installations

• Heat pump installations

• Furnace replacements

• New home construction

 

Many jurisdictions require a Manual J before approving HVAC permits.

 

What Is Comcheck?

Comcheck is the commercial equivalent of REScheck.

It is used to demonstrate energy code compliance for:

• Commercial buildings

• Mixed-use buildings

• Multi-family buildings over three stories

• Tenant improvements

 

Comcheck evaluates:

• Building envelope

• Lighting power density

• Mechanical systems

 

If your project is not classified as residential under IECC, you likely need Comcheck instead of REScheck.

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When Do You Need Each One?

Here is a simplified breakdown:

New Home Construction

• ✔ REScheck

• ✔ Manual J

• ❌ COMcheck

Room Addition

• ✔ REScheck

• Possibly Manual J (if HVAC changes)

• ❌ COMcheck

HVAC Replacement Only

• ❌ REScheck

• ✔ Manual J

• ❌ COMcheck

Heat Pump Installation

• ❌ REScheck

• ✔ Manual J

• ❌ COMcheck

Commercial Building

• ❌ REScheck

• Sometimes Manual J

• ✔ COMcheck

Multi-Family (Over 3 Stories)

• ❌ REScheck

• Possibly Manual J

• ✔ COMcheck​

 

Quick Comparison Table

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Can You Need More Than One?

Yes — many projects require both a REScheck and a Manual J.

For example:

• A new home requires envelope compliance (REScheck) and proper HVAC sizing (Manual J).

• A large addition may require REScheck for insulation compliance and Manual J if HVAC is upgraded.

Understanding this distinction helps prevent permit delays.

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How Do You Know Which One Your City Requires?

Local jurisdictions adopt different versions of the IECC (2018, 2021, 2024). Requirements vary by state and municipality.

If you're unsure, check with your building department — or contact us and we can help clarify what your project requires.

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Summary

• REScheck = Residential energy code compliance

• Manual J = HVAC sizing calculation

• COMcheck = Commercial energy code compliance

Each serves a different purpose, and choosing the correct report ensures faster permit approval and smoother inspections.