Texas REScheck Requirements (2026)

​​​​​​​​​⚠ The Statewide Minimum Applies in Unincorporated Areas of Counties: Texas Health and Safety Code §388.004 is explicit — the adopted energy code applies not just within city limits but also in unincorporated county areas. A new home built outside city limits is still subject to the state minimum. County judges and commissioners courts enforce code there; verify enforcement capacity with the county.

 

Blower Door and Duct Requirements

Blower Door (Air Leakage Testing)

• Zones 2 & 3 (statewide minimum): max 5 ACH50 — mandatory, no visual inspection alternative

• Zone 4: max 3 ACH50 — mandatory

• Cities on 2021 IECC (Austin, Houston, Dallas, San Antonio): max 3 ACH50 statewide, significantly stricter than state minimum

• Testing per RESNET/ICC 380, ASTM E779, or ASTM E1827; written signed report required

• Mechanical ventilation required when result falls below 5 ACH50 (2015 IRC) or below 3 ACH50 (2021 IECC)

• Zone 2 prohibition: electric resistance heating can't be the primary system for new construction or full replacements

 

Duct Leakage Testing

• Post-construction: max 4 CFM25 per 100 sq ft — mandatory regardless of duct location (unlike most states, tested even when ducts are inside conditioned space)

• Rough-in: max 4 CFM25/100 sq ft with air handler; 3 CFM25 without

• Supply ducts in unconditioned attics: min R-8; other supply/return ducts outside conditioned space: min R-6

• Framing cavities may NOT be used as supply or return ducts; duct sealing requires mastic or equivalent (duct tape alone unacceptable)

 

Common REScheck Failure Reasons in Texas

Envelope Errors by Zone

• Wrong climate zone — placing a DFW project in Zone 2 instead of Zone 3; Dallas County is Zone 3, Houston is Zone 2

• Zone 2 wall insulation — state minimum allows R-13 cavity-only, but Austin/Houston/San Antonio's 2021 IECC requires R-20 or R-13+5ci

• Zone 4 ceiling requirement — Amarillo/Lubbock need R-49, not Zone 3's R-38

• SHGC non-compliance — 0.25 applies to Zones 2/3 and can't be traded off; large window packages on custom homes frequently exceed it, especially in Houston and Austin

• Wrong code year selected in REScheck — using statewide 2015 IRC Ch. 11 for an Austin (2024 IECC) or Houston (2021 IECC) project

 

Mechanical and Field Issues

• Blower door failures from top plate/recessed lighting/boot/plumbing chase leaks, even at the lenient 5 ACH50 threshold

• Duct leakage failures in attic systems — 150°F+ attic temps degrade duct tape rapidly; mastic sealing is critical

• Duct testing documentation missing — Texas requires it even for conditioned-space ducts

• Electric resistance heat used as primary system in Zone 2 — violates code; heat pumps or gas required

• Energy certificate omitted at furnace/utility room — frequently overlooked final inspection item

• Manual J documentation missing — oversized systems without load calc are a frequent correction

 

Frequently Asked Questions

What energy code does Texas currently use for residential construction?

The statewide minimum is the 2015 IRC Chapter 11, effective September 1, 2016, adopted by SECO. This remains current as of June 2026. Austin enforces the 2024 IECC; Houston, Dallas, and San Antonio enforce the 2021 IECC. SB 783 (Sept 1, 2025) authorized SECO to begin rulemaking toward a newer edition, expected by mid-2026. Always verify with the local permit office.

 

What climate zones does Texas have?

Three: Zone 2 (Hot-Humid — Houston, San Antonio, Austin, Corpus Christi, McAllen, Laredo, Brownsville), Zone 3 (Mixed — Dallas, Fort Worth, Waco, Tyler, Midland, Abilene), Zone 4 (Cold — Amarillo, Lubbock, Wichita Falls). Zone is determined by county and is the single most important input for a Texas REScheck.

 

Is blower door testing required in Texas?

Yes, mandatory statewide. Under the state minimum: 5 ACH50 for Zones 2/3, 3 ACH50 for Zone 4. Cities on the 2021 IECC (Austin, Houston, Dallas, San Antonio) require 3 ACH50 for all zones. There is no visual inspection alternative in Texas.

 

Do I need a REScheck for a barndominium in Texas?

Yes, if conditioned and the local jurisdiction has adopted an energy code — regardless of steel-frame, post-frame, or stick-built construction. SHGC 0.25 in Zones 2/3 is especially important on barndominiums with large roll-up door windows.

 

Do I need a REScheck for an ADU in Texas?

Yes, in most jurisdictions — ADUs are generally treated as new residential construction. Austin applies the 2024 IECC to ADUs; Houston, San Antonio, and Dallas apply the 2021 IECC. Smaller cities and unincorporated areas use the statewide 2015 IRC minimum.

 

What SHGC is required in Texas?

0.25 maximum in Zones 2 and 3 (the vast majority of the state, including all major cities) — mandatory, cannot be traded off. 0.40 maximum in Zone 4 (Amarillo, Lubbock, Panhandle).

 

What does the Texas HERS/ERI path require?

Available statewide under Health & Safety Code §388.003. Max ERI (as of Sept 1, 2022) is 59 for Zones 2/3, 63 for Zone 4 — stepped down from 65 (2016) to 63 (2019). Certified HERS Rater required. Texas does not require an R408 additional efficiency package on the ERI path. Zone 2 still can't use electric resistance heat as the primary system.

 

When will Texas update its statewide energy code?

In active rulemaking. SB 783 (Sept 1, 2025) resolved conflicting statutes that had blocked SECO from updating. A public input request on the 2024 IECC went out in November 2025; a draft rule is expected by mid-2026. Until formally adopted and published in the Texas Register, the 2015 IRC Chapter 11 remains the statewide minimum.

 

Does the Texas energy code apply outside city limits?

Yes. Health & Safety Code §388.004 applies the adopted energy code in unincorporated county areas as well as cities. County judges and commissioners courts enforce it, though enforcement capacity varies — verify with the county.