Texas's Residential Energy Code, City by City: What REScheck and Manual J Actually Require

1. What the Code Is and Who Enforces It

Texas is not a "single statewide code" state the way, say, Florida or Georgia are. State law sets a floor, and Texas's home-rule structure lets any city or county build a taller floor on top of it. That distinction matters more in Texas than almost anywhere else, because the gap between the state minimum and what a major metro actually enforces can span three code cycles.

The statewide minimum

Under the Texas Health & Safety Code, Chapter 388, the state's mandatory minimum residential energy standard for one- and two-family dwellings is Chapter 11 of the 2015 International Residential Code, which incorporates the energy provisions of the 2015 International Energy Conservation Code (IECC). For other residential building types and commercial construction, the 2015 IECC applies directly. This is confirmed on the Texas Comptroller's State Energy Conservation Office (SECO) "Local Ordinances" page, which states plainly: "The minimum state-mandated code for single-family homes is Chapter 11 of the 2015 International Residential Code. The applicable code for other residences and commercial and industrial buildings is the 2015 International Energy Conservation Code."¹ The U.S. Department of Energy's Building Energy Codes Program confirms the same baseline from the federal side: Current State Code (Residential) = "2015 IECC with Amendments," adopted June 14, 2015, effective September 1, 2016, with state amendments and "Can use COM/REScheck: Yes."²

Home rule and local amendments

SECO's own page spells out how Texas is a "home rule" state that allows local jurisdictions to adopt amendments to the codes - but with a check: to amend the state code in non-attainment and affected counties, the Energy Systems Laboratory at Texas A&M University must first determine, at the request of a municipality or county, whether the amended code is at least as stringent as the existing state code. Code changes found equal to or more stringent may then be adopted locally.¹ In practice, this means Texas cities can move ahead of the state - they can't move behind it. The ICC's own state adoption map for Texas confirms the structural point: "building code adoption in Texas takes place at the local level," and it lists Houston, Austin, Dallas, San Antonio, Fort Worth, Travis County, Harris County, and Bexar County as the places to check for the actual adopted code in effect.³ (That same ICC page also flags a narrow statewide requirement for industrialized housing - factory-built modular homes regulated by the Texas Department of Licensing and Regulation - which must comply with the 2021 IECC as of July 1, 2024. That's a separate program from standard site-built residential permitting and doesn't change the Health & Safety Code Chapter 388 minimum described above.³)

Who enforces it

Enforcement is entirely local. There is no statewide plan-review agency for residential energy code the way some states run one; your city or county building/development-services department reviews the permit, checks the compliance documentation, and signs off. That means two things in practice:

• The code edition, the amendments layered on top of it, and even the accepted documentation format can differ from one city to the next - sometimes across a single metro area, where a project just outside city limits falls under a different county or unincorporated-area standard than a project two blocks away inside city limits.
• "Texas requires X" is rarely a complete answer. The complete answer is "the state requires at least X, and your jurisdiction requires Y" - and Y is what your plan reviewer actually checks.

Climate zones

Texas spans five IECC climate zones: 2A, 2B, 3A, 3B, and 4B.⁴ In practical terms, using the county-by-county breakdown in the 2015 IECC's own climate zone table:

• Zone 2 (hot-humid, and a smaller hot-dry pocket near the Rio Grande) covers Houston/Harris County, San Antonio/Bexar County, Austin/Travis County, the Gulf Coast, and the Rio Grande Valley.
• Zone 3 (mixed-humid, and a mixed-dry band to the west) covers Dallas-Fort Worth/Dallas and Tarrant counties, Waco, Tyler, El Paso, Lubbock, Midland-Odessa, and most of the state's interior.
• Zone 4 (dry) covers the far northern Texas Panhandle - Amarillo and the surrounding counties.

This geographic breakdown comes from a Texas-focused compliance guide built directly from the 2015 IECC's official climate zone map and hosted by a Texas municipality; it doesn't distinguish the A/B (moist/dry) subzone split within each zone number, but for the prescriptive insulation and fenestration table (R402.1.2) covered in Section 2 below, the A/B split doesn't change the R-value or U-factor requirements - only the zone number does.⁵ If your project sits near a zone boundary, confirm the exact designation with your local building department rather than assuming from the city name alone.

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2. What Actually Changed / Where Cities Exceed the State Minimum

Two separate things are true in Texas, and conflating them is the single most common mistake we see in permit submittals from out-of-state builders or DIY homeowners:

1. The statewide minimum hasn't moved since 2015. There's no pending statewide update the way Pennsylvania or Delaware just went through.
2. Individual cities have moved well past it - some by one code cycle (2018), some by two (2021), and Austin by three (2024) - each with its own local amendments layered on top.

Here's what the 2015 IECC statewide minimum actually requires, verified directly against ICC's own published code text, followed by what each major metro enforces instead.

The 2015 IECC statewide minimum - prescriptive table (R402.1.2)

Every Texas jurisdiction that hasn't adopted something newer is bound by Table R402.1.2 of the 2015 IECC. Pulled directly from ICC Digital Codes, here's what it requires for the three climate zones that cover Texas:⁶

Component	Zone 2	Zone 3	Zone 4 (except Marine)
Fenestration (window) U-factor, max	0.40	0.35	0.35
Skylight U-factor, max	0.65	0.55	0.55
Glazed fenestration SHGC, max	0.25	0.25	0.40
Ceiling R-value	R-38	R-38	R-49
Wood-frame wall R-value	R-13	R-20 or R-13+5ci	R-20 or R-13+5ci
Floor R-value	R-13	R-19	R-19
Basement wall R-value	0	R-5/13	R-10/13
Slab edge R-value, depth	0	0	R-10, 2 ft
Crawlspace wall R-value	0	R-5/13	R-10/13

Source: ICC Digital Codes, 2015 IECC Table R402.1.2, "Insulation and Fenestration Requirements by Component" (codes.iccsafe.org).⁶ R-values are minimums; U-factors and SHGC are maximums. "13+5ci" means R-13 cavity insulation plus R-5 continuous insulation.

Mandatory air-leakage testing: Section R402.4.1.2 of the 2015 IECC requires the building to be tested and verified as having an air leakage rate not exceeding 5 air changes per hour (5 ACH50) in Climate Zones 1 and 2, and 3 air changes per hour (3 ACH50) in Climate Zones 3 through 8, measured at 50 Pascals per ASTM E779 or ASTM E1827.⁷ That means most of the Houston, San Antonio, and Austin metro areas (Zone 2) get the looser 5 ACH50 limit under the statewide minimum, while Dallas-Fort Worth, El Paso, Lubbock, and the Panhandle (Zones 3 and 4) are held to the tighter 3 ACH50 limit - a distinction that disappears entirely once a city adopts a newer IECC edition, most of which apply the same test but often with different local mandatory-testing thresholds bundled into the local amendment package.

Duct testing and insulation: Under the 2015 IECC's Section R403.3, ducts must be tested and verified to leak no more than 4 CFM per 100 sq. ft. of conditioned floor area (with the air handler installed) or 3 CFM per 100 sq. ft. (without), except where the air handler and all ducts are located entirely inside conditioned space, which is exempt from testing. Supply and return ducts in attics require a minimum of R-6 (under 3 inches diameter) or R-8 (3 inches or larger); ducts elsewhere in unconditioned space require R-4.2 or R-6.⁸ These numeric thresholds are unchanged across the 2015 through 2021 IECC editions, so they apply the same way whether your jurisdiction is on the statewide minimum or a city's newer adoption.

The UA alternative and ERI path exist under the 2015 IECC too

If your wall assembly, glazing package, or floor plan can't clear every line of Table R402.1.2 individually, the 2015 IECC's Section R402.1.5 provides a total UA (thermal transmittance) trade-off alternative - the same concept documented by a REScheck report under newer editions - and Section R406 provides an Energy Rating Index (ERI/HERS) performance path. Both paths exist under the statewide minimum, not just under the newer editions cities have adopted; which path is fastest and cheapest to document depends on your specific design, covered in Section 3.

Where cities exceed the minimum: a city-by-city comparison

This is the part that actually determines what you need to submit. Verified directly against each city's own development-services or building-code page - not a national summary or a third-party code aggregator:

City	Currently adopted energy code	Effective date	Source
Austin	2024 IECC with local amendments	July 10, 2025	Austin Development Services, "Building Technical Codes"9
Houston	2021 IECC with Houston amendments	January 1, 2024 (Ord. No. 2023-907)	Houston Permitting Center, code archive/adoption pages10
Dallas	2021 IECC with Dallas amendments (Chapter 59)	May 12, 2023	Dallas City Hall, "Current City Code"11
San Antonio	2021 IECC with San Antonio amendments (Ch. 10)	February 1, 2023 (Ord. 2021-11-10-0875)	City of San Antonio, Chapter 10 Building-Related Codes12
Fort Worth	2015 IECC with local amendments (or 2013 ASHRAE 90.1, builder's choice)	January 1, 2017 (Ord. 22520-12-2016)	City of Fort Worth, "Building & Energy Codes"13
Georgetown	2021 IECC with local amendments	November 1, 2023 (Ord. 2023-43)	City of Georgetown, "Adopted Building Code" / "Residential Permits"14

The headline finding: Fort Worth is the outlier. Every one of the other five cities we checked has moved past the statewide 2015 minimum - most to the 2021 IECC, Austin all the way to 2024. Fort Worth's own Building & Energy Codes page, as of this research, still lists the 2015 International Energy Code with Local Amendments as current, alongside the 2021 editions of its building, mechanical, residential, and plumbing codes - meaning Fort Worth updated most of its construction codes to the 2021 cycle but left the energy code on the 2015 cycle.¹³ That's an unusual split, and it's exactly the kind of detail a national "Texas requires 2021 IECC" article would miss.

Georgetown is worth calling out specifically because its own permit-submittal pages are unusually explicit: both the "New Residential Construction" page and the "Garage Conversion" page list a "ResCheck Form (2021 Energy Conservation Code)" as a required submittal document, with a direct link to the DOE's REScheck tool.¹⁴ That's a rare case of a Texas building department stating, in writing, exactly which compliance document it wants attached to the permit application - most cities require energy code compliance but leave the documentation format to the code text itself rather than spelling it out on a checklist.

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3. Your Ways to Comply

Whichever IECC edition applies to your project - 2015, 2018, 2021, or 2024 - the same three general paths to compliance exist, carried forward with only minor changes across editions:

Path	Typical code section	What it is	Best fit
Prescriptive	R402.1.1/R402.1.2	Meet every line item in the R-value/U-factor table for your climate zone, exactly as published.	Simple plans, standard 2x6 framing, no unusual glazing, tight budget and timeline.
UA / total-building-envelope trade-off (REScheck)	R402.1.5	Total heat loss (UA) of the actual envelope must be at or below the UA of a prescriptive-minimum reference home. Weak components can be offset by strong ones elsewhere.	2x4 walls, large glazing packages, or an assembly that can't hit every prescriptive number individually but performs well overall.
Simulated performance / Energy Rating Index (ERI/HERS)	R405 / R406	A full energy model or HERS rating compares the proposed design's performance against a standard reference design or scores it on the 0-100 ERI scale.	Custom homes, non-standard HVAC or renewable strategies, or projects already doing a HERS rating for a rebate, tax credit, or green certification.

Honest guidance on which path fits which project:

• Simple, code-minimum spec homes with standard framing - run the prescriptive path. It's the fastest through plan review and the cheapest to document, because there's nothing to argue about: the wall assembly either matches the table or it doesn't.
• 2x4 walls, large window packages, or one component that's short of the table - the UA trade-off (REScheck) is usually the cheapest fix. A REScheck report documents the offset in a same-day report rather than a multi-week energy model, and it's the pathway most Texas plan reviewers see most often on residential permits.
• Custom homes, unusual HVAC, or a design the prescriptive/UA path can't cleanly capture - go simulated performance. It costs more and takes longer, but it's the only path flexible enough for genuinely non-standard designs.
• Already paying for a HERS rating for ENERGY STAR, DOE ZERH, a utility rebate, or the federal 45L tax credit - use the ERI path and let that rating do double duty as code compliance, instead of also paying for a separate REScheck report.

Which REScheck edition to select matters as much as which path. The DOE REScheck tool supports IECC editions from 2009 through 2024, which is exactly why it's usable across Texas's full range of local adoptions - the statewide 2015 minimum, Fort Worth's 2015 code, Houston/Dallas/San Antonio/Georgetown's 2021 codes, and Austin's 2024 code all have a matching REScheck edition.² Selecting the wrong edition - say, running a Houston project through the tool's 2015 IECC setting because that's what "Texas" defaults to in your head - produces a report your reviewer will kick back, even though the software itself accepted the inputs without complaint.

What about Manual J? Every IRC edition Texas cities have adopted (2012 through 2021, depending on jurisdiction) carries Section M1401.3, which requires heating and cooling equipment to be sized in accordance with ACCA Manual S, based on building loads calculated using ACCA Manual J (or another approved equivalent method).¹⁵ That's not an energy-code requirement layered on top by a city - it's baked into the residential code itself, and it applies regardless of which IECC edition covers your energy compliance path. Some Texas building departments ask for the Manual J report up front with the permit submittal; others only ask for it if a reviewer flags equipment that looks oversized relative to the house. Either way, a documented, room-by-room Manual J protects you against a stop-work or re-inspection request mid-project, and it's the same calculation your HVAC contractor needs to size the system correctly in the first place.

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City sections: San Antonio and Houston

These are the two Texas cities we have read submittal documents for line by line. Link straight to one: #san-antonio or #houston. Other Texas jurisdictions are not covered here; confirm the department that will actually review your permit.

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4. Texas-Specific Wrinkles

"Texas code" isn't one thing - confirm the jurisdiction, not the state. With hundreds of incorporated cities and dozens of counties each free to adopt their own code cycle, the single biggest risk on a Texas project is assuming last year's spec sheet from a different city still applies. A builder who works Austin and San Antonio jobs back to back is working under two different code editions (2024 IECC vs. 2021 IECC) with two different sets of local amendments, even though both cities are in the same climate zone.

Unincorporated county land defaults to the state minimum more often than city land. Because energy-code adoption happens at the municipal level, projects outside any city's limits - in unincorporated Harris, Travis, Bexar, or Tarrant County, for instance - are more likely to fall under the statewide 2015 IECC/IRC minimum unless the county itself has separately adopted something newer. Don't assume a project "near Austin" is under Austin's 2024 code just because of the address; confirm whether the parcel is inside city limits, inside the extraterritorial jurisdiction (ETJ), or in unincorporated county land, because each can carry a different adopted code.

Grandfather/permit-date rules vary by city, and most cities don't publish a Pennsylvania-style formal grace period. Some jurisdictions apply the code in effect on the date of permit application; others apply the code in effect at plan submittal or at a specific adoption-ordinance cutover date. Houston's code-word interpretation guidance, for example, spells out specific rules for which code edition applies based on original application date relative to the ordinance's effective date.¹⁰ Don't assume a Pennsylvania-style uniform six-month grace period exists statewide in Texas - ask your specific jurisdiction which code edition applies to your permit application date.

Energy Systems Laboratory review only applies in non-attainment/affected counties. SECO's ordinance page notes that the Energy Systems Laboratory at Texas A&M must certify a local amendment as at-least-as-stringent before it can be adopted, but only "to amend the state code in non-attainment and affected counties" - a designation tied to federal air-quality rules, not a blanket statewide requirement.¹ This is largely a background administrative detail for builders, but it explains why some DFW-area and Houston-area amendments went through a formal stringency review while smaller-market cities elsewhere in the state didn't need to.

"Can use REScheck" doesn't mean every city documents compliance the same way. Georgetown explicitly names a "ResCheck Form" on its permit checklist.¹⁴ Other cities require energy-code compliance without naming the specific document format on a public checklist, leaving it to the code text (and your plan reviewer's judgment) to decide whether a REScheck printout, a UA-trade-off worksheet, or an ERI/HERS certificate satisfies the requirement. When a jurisdiction doesn't spell it out, a REScheck report matched to the correct adopted edition is the safest default - it's the one document format the DOE's own IECC/IRC energy provisions were written to be checked against.

What to ask your local building department before you finalize a compliance strategy:

1. Which IECC and IRC editions does this specific jurisdiction currently enforce for residential permits - and is my project inside city limits, in the ETJ, or in unincorporated county land?
2. Which code edition applies to my project: the one in effect at permit application, at plan submittal, or at a fixed ordinance cutover date?
3. Do you require a specific compliance-document format (REScheck printout, UA worksheet, or HERS/ERI certificate) submitted with the permit application, or is it reviewed at a later inspection stage?
4. Do you require a Manual J load calculation to be submitted with the permit, or only upon request?
5. Who is your approved third party for blower-door and duct-leakage testing, and which test protocol do you require (ASTM E779, ASTM E1827, or RESNET/ICC 380)?

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5. Frequently Asked Questions

Does Texas have one statewide residential energy code? There's a statewide minimum - Chapter 11 of the 2015 IRC (which incorporates the 2015 IECC) for single-family homes - but Texas is a home-rule state, so any city or county can adopt a stricter, newer edition with its own amendments.¹ Austin, Houston, Dallas, San Antonio, and Georgetown are all currently enforcing 2018 or later editions, and Fort Worth's own energy-code page still lists the 2015 IECC as current. Always confirm the specific edition with the jurisdiction issuing your permit.

Will a REScheck report be accepted for a Texas permit? Yes. The DOE's state energy code page lists Texas as "Can use COM/REScheck: Yes" for both the statewide 2015 IECC minimum and, since the tool supports IECC editions from 2009 through 2024, for the newer editions Austin, Houston, Dallas, San Antonio, and Georgetown have adopted locally.² The key is selecting the correct code edition for your jurisdiction inside the tool - not just any IECC year.

Which IECC edition does my city actually enforce? It varies and changes over time. As of this page's research: Austin enforces the 2024 IECC (effective July 10, 2025); Houston, Dallas, San Antonio, and Georgetown enforce the 2021 IECC with local amendments; Fort Worth's own development-services page still lists the 2015 IECC as its current energy code.⁹ Smaller cities and unincorporated county areas often default to the 2015 statewide minimum unless they've adopted something newer - confirm directly with your building department.

Is a Manual J load calculation required for a Texas HVAC permit? The IRC's Section M1401.3 requires HVAC equipment to be sized according to ACCA Manual S based on loads calculated per ACCA Manual J or an equivalent approved method, and every major Texas metro has adopted an IRC edition that includes this section.¹⁵ Some building departments ask for the report to be submitted with the permit; others only request it if a reviewer flags an oversized or undersized system. Having a documented Manual J on hand protects you either way.

Who prepares these reports? Travis Smith, The Plans Examiner. He holds the same certification your building department's plan reviewer holds; the specifics are at the end of this page.

My city isn't one of the ones covered on this page - what do I do? Texas has hundreds of incorporated cities, and none of them are required to follow the same code cycle, so this page can't cover every jurisdiction by name. Check your city or county's building/development-services website for its adopted code list, or call the plan review desk and ask which IECC and IRC editions apply to residential permits. If you can't find a clear answer online, tell us when you order a report and we'll build in a buffer rather than guess at an edition.

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6. Get It Right the First Time - Before Plan Review Sends It Back

Need a REScheck report matched to your city's actual adopted edition? The single most common reason a Texas REScheck submittal gets kicked back isn't a bad input - it's the wrong code year. A report run against the statewide 2015 IECC default won't satisfy Austin's 2024 code, and a report run against a generic "current" IECC setting may not match Houston's, Dallas's, or San Antonio's 2021-with-local-amendments version either. We confirm your project's jurisdiction and its currently adopted edition before running the report. A REScheck report is $149, delivered ready to attach to your permit application.

Need a Manual J load calculation? IRC M1401.3 ties equipment sizing directly to a documented Manual J, and a growing number of Texas jurisdictions - Georgetown among them - expect to see it with the submittal, not after the fact. A room-by-room Manual J report prepared in ACCA-approved software gives you defensible equipment sizing your HVAC contractor and building department can both stand behind. A Manual J report is $249.

Need both? The combined Manual J + REScheck package is $349 - one submission covering both the equipment-sizing requirement under the residential code and the envelope/compliance requirement under whichever IECC edition your city enforces.

Already been rejected? If your jurisdiction has already sent the report back, we work from the correction notice itself - see REScheck correction and resubmittal or Manual J correction and resubmittal.

Every report comes with the same guarantee: accepted by your building department, or we revise it free until it clears.

Contact us with your plans and the city or county where you're pulling the permit, and we'll confirm the adopted code edition and tell you plainly which compliance path fits your project - not a generic "Texas" answer.

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Verification Appendix

Every jurisdiction-specific claim on this page was checked directly against that jurisdiction's own published code-adoption page, ordinance, or permit-submittal checklist during this research pass - not a national aggregator or a secondary blog summary, except where explicitly noted below.

1. Statewide minimum = Chapter 11, 2015 IRC / 2015 IECC. VERIFIED. Texas Comptroller SECO "Local Ordinances" page states this directly in its own words: "The minimum state-mandated code for single-family homes is Chapter 11 of the 2015 International Residential Code. The applicable code for other residences and commercial and industrial buildings is the 2015 International Energy Conservation Code."¹ Corroborated independently by the DOE energycodes.gov Texas state profile, which lists Current State Code (Residential) = "2015 IECC with Amendments."²

2. DOE "Can use COM/REScheck" = Yes for Texas. VERIFIED. energycodes.gov/status/states/texas lists "Can use COM/REScheck: Yes" for both Commercial and Residential.²

3. 2015 IECC Table R402.1.2 values for Zones 2, 3, and 4. VERIFIED (primary source). Pulled directly from ICC Digital Codes (codes.iccsafe.org), the official published text of the 2015 IECC.⁶

4. 2015 IECC R402.4.1.2 blower-door thresholds (5 ACH50 Zones 1-2, 3 ACH50 Zones 3-8). VERIFIED. Confirmed against a direct excerpt of the 2015 IECC's own section text (Southface Energy Institute's published 2015 IECC Chapter 4 excerpt), matching the standard national code language.⁷

5. 2015 IECC R403.3 duct-testing thresholds. VERIFIED, secondary corroboration. Confirmed against a Texas-focused "IECC Compliance Guide for Homes in Texas" reproducing the 2015 IECC's duct-testing and duct-insulation language, hosted on a Texas municipal government domain.⁸ These numeric thresholds are well-established and unchanged across the 2015-2021 IECC editions generally, but this page relies on the secondary Texas-hosted compliance guide rather than a direct ICC Digital Codes pull for R403.3's exact section text, since that page required a paid subscription to print/extract during this research session.

6. Austin = 2024 IECC, effective July 10, 2025. VERIFIED. Austin Development Services' own "Building Technical Codes" page lists the IECC local amendment as "2024," effective July 10, 2025.⁹

7. Houston = 2021 IECC with amendments, effective January 1, 2024. VERIFIED. Houston Permitting Center's own code-development and code-archive pages confirm the 2021 Houston Construction Code (including Exhibit C, Houston Amendments to the 2021 IECC) was adopted by Ordinance No. 2023-907, passed October 25, 2023, effective January 1, 2024.¹⁰

8. Dallas = 2021 IECC with Dallas amendments, effective May 12, 2023. VERIFIED. Dallas City Hall's own "Current City Code" page lists Chapter 59 as "2021 International Energy Conservation Code with Dallas Amendments," with construction codes effective May 12, 2023.¹¹

9. San Antonio = 2021 IECC, effective February 1, 2023. VERIFIED. The City of San Antonio's own Chapter 10 "Building-Related Codes" document states an effective date of February 1, 2023, under Ordinance No. 2021-11-10-0875, adopted November 10, 2022, covering the 2021 editions of the International Building-Related Codes including the IECC.¹²

10. Fort Worth = 2015 IECC (not yet updated to 2021), effective January 1, 2017. VERIFIED. Fort Worth's own "Building & Energy Codes" development-services page explicitly states, as of this research date: "the current standard being the 2015 International Energy Conservation Code (IECC)," while separately listing 2021 editions of its Building, Mechanical, Residential, and Plumbing codes - confirming the energy code specifically was not updated alongside the others.¹³ The underlying adoption ordinance (22520-12-2016) is dated December 6, 2016, effective January 1, 2017.

11. Georgetown = 2021 IECC, effective November 1, 2023; REScheck named explicitly on permit checklists. VERIFIED. Georgetown's own "Adopted Building Code" page lists the 2021 IECC among "Adopted Codes effective November 1, 2023" (Ordinance 2023-43). Separately, both the "New Residential Construction" and "Garage Conversion" pages on georgetowntexas.gov list a "ResCheck Form (2021 Energy Conservation Code)" / "REScheck form" as a required submittal document, with a direct link to energycodes.gov.¹⁴

12. Climate zones 2A, 2B, 3A, 3B, 4B for Texas. VERIFIED (DOE designation), UNVERIFIED at county level for the A/B moisture subzone split. The five-zone list is confirmed against the DOE/IECC climate zone framework for Texas. The county-to-zone geographic breakdown used in Section 1 comes from a Texas-hosted compliance guide that maps counties to zone numbers (2, 3, 4) without confirming the A/B subzone designation county-by-county; that subzone split doesn't affect the R402.1.2 insulation/fenestration table values used in Section 2, but if your project depends on an A/B-specific provision elsewhere in the code (e.g., the "warm-humid" basement-wall exemption), confirm your exact subzone with your local building department or the ASHRAE/IECC climate zone map directly.

13. IRC M1401.3 (Manual J equipment sizing requirement). VERIFIED as a stable, standard IRC citation. This section number and its substance (equipment sized per ACCA Manual S based on ACCA Manual J loads) is consistent across the IRC editions (2012 through 2021) adopted by the Texas jurisdictions covered on this page; it was not independently re-pulled from ICC Digital Codes for each specific city's adopted IRC edition during this research pass, since the section's core requirement has not materially changed across those editions nationally.

What remains genuinely unconfirmed: the exact energy code in effect for cities and counties not named on this page (there are hundreds); Fort Worth's precise local amendment text to the 2015 IECC beyond the base edition; and the precise grandfather/permit-date rule for each city listed (only Houston's was directly documented in this pass). Confirm any of these directly with the relevant building department before finalizing a compliance strategy.

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Sources

This page summarizes the statewide minimum and six major-city adoptions of the Texas residential energy code for general guidance. Because Texas energy code adoption happens jurisdiction-by-jurisdiction, requirements for any specific city or county not named here may differ. Always confirm current requirements with your local building department before finalizing design or bidding.