§ Chapter 11 IRC 2021
Energy Efficiency
14 entries from Chapter 11 of IRC 2021, organized by section number. Each entry covers what the code requires, why it exists, what inspectors look for, and common mistakes.
§ 01 Sections
All 14 entries.
Sorted by section number. Click any row for the full entry — answer, requirements, edition diff, related sections.
Section
Title
Question
R1101.13
IRC Chapter 11 Allows Prescriptive, Performance, ERI, and Tropical Compliance Paths
R1101.13
Do I have to follow the prescriptive insulation table, or can I use REScheck, performance, or a HERS rating?
Do I have to follow the prescriptive insulation table, or can I use REScheck, performance, or a HERS rating?
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R1101.14
A Permanent Energy Certificate Must Be Posted in the Dwelling
R1101.14
What is the energy certificate sticker by the furnace or electrical panel, and is it required?
What is the energy certificate sticker by the furnace or electrical panel, and is it required?
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R1102.1.2
Window U-Factor and SHGC Limits Are Set by Climate Zone
R1102.1.2
What U-factor and SHGC do my windows and glass doors need for the 2021 energy code?
What U-factor and SHGC do my windows and glass doors need for the 2021 energy code?
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R1102.1.3
Insulation R-Values Depend on the IECC Climate Zone and Assembly Type
R1102.1.3
What R-value insulation do I need for walls, ceilings, floors, basement walls, slabs, and crawl spaces?
What R-value insulation do I need for walls, ceilings, floors, basement walls, slabs, and crawl spaces?
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R1102.1.4
Continuous Insulation Is Separate From Cavity Insulation in the Energy Code
R1102.1.4
What does 20 plus 5 ci, 13 plus 10 ci, or continuous insulation mean in the 2021 IECC?
What does 20 plus 5 ci, 13 plus 10 ci, or continuous insulation mean in the 2021 IECC?
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R1102.1.5
Component Performance Allows Some Envelope Tradeoffs but Not Unlimited Substitutions
R1102.1.5
Can I use better windows to make up for lower wall or attic insulation, or trade insulation values in the energy code?
Can I use better windows to make up for lower wall or attic insulation, or trade insulation values in the energy code?
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R1102.2.9
Basement Wall Insulation Is Required by Climate Zone When the Basement Is in the Thermal Envelope
R1102.2.9
Do basement walls need insulation under the 2021 IRC energy code?
Do basement walls need insulation under the 2021 IRC energy code?
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R1102.2.10
Slab Edge Insulation Requirements Increase in Colder Climate Zones
R1102.2.10
When is slab edge insulation required, and how deep does it have to go?
When is slab edge insulation required, and how deep does it have to go?
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R1102.2.11
Crawl Space Energy Compliance Depends on Vented or Unvented Design
R1102.2.11
Do I insulate the crawl space walls or the floor above the crawl space under the 2021 energy code?
Do I insulate the crawl space walls or the floor above the crawl space under the 2021 energy code?
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R1102.5.1.1
Air Sealing Must Create a Continuous Thermal Envelope
R1102.5.1.1
What does the inspector look for on the energy code air sealing inspection?
What does the inspector look for on the energy code air sealing inspection?
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R1102.5.1.3
IRC 2021 Requires Blower Door Testing for Building Air Leakage
R1102.5.1.3
Is a blower door test required, and what ACH number does a new house have to pass?
Is a blower door test required, and what ACH number does a new house have to pass?
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R1103.3.3
Ducts Outside Conditioned Space Need Insulation and Leakage Control
R1103.3.3
What R-value insulation is required for HVAC ducts in an attic, crawl space, garage, or outside conditioned space?
What R-value insulation is required for HVAC ducts in an attic, crawl space, garage, or outside conditioned space?
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R1103.3.7
Duct Systems Must Be Sealed and Tested for Leakage
R1103.3.7
Do my HVAC ducts need a duct leakage test for the 2021 energy code?
Do my HVAC ducts need a duct leakage test for the 2021 energy code?
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R1103.6
Tight New Homes Need Whole-Dwelling Mechanical Ventilation
R1103.6
If my house passes the blower door test, do I also need a fresh air system, ERV, HRV, or whole-house ventilation?
If my house passes the blower door test, do I also need a fresh air system, ERV, HRV, or whole-house ventilation?
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