CONTRACTOR & GENERAL CONTRACTOR ONLY SERVICE | 48-HOUR TURNAROUND — SEE TERMS | 24-HOUR RUSH AVAILABLE | 5-STAR RATED BY CONTRACTORS NATIONWIDE
HVAC Calculation Services for Texas Contractors
Manual J • Manual D • Manual S • Manual Q • Manual N • COMCheck
Outsourced & Permit-Ready | Built for All 5 Texas Climate Zones
Permit-ready load calculations and duct designs for HVAC contractors and general contractors across Texas , residential and commercial. Nationwide service, 48-hour turnaround (see terms…).
ACCA-APPROVED | 2018 IECC COMPLIANT | 48-HOUR TURNAROUND | CONTRACTOR-ORIENTED SERVICE | NATIONWIDE | 120+ YEARS COMBINED HVAC EXPERIENCE.
MANUAL J LOAD CALCULATION REPORT FOR TEXAS HVAC CONTRACTOR
Sample Manual J load calculation prepared for a Texas residential project.
THE QUESTION IS NOT 'WHY', BUT WHY NOT?
AC Duct Design & Manual J Services Built for Every Texas Climate Zone — From the Gulf Coast to the Panhandle
Every report is permit-ready and delivered straight to your inbox, usually within 48 hours (anywhere in Texas or nationwide).
Texas spans five distinct IECC climate zones, each with its own heating and cooling demands, which means a Manual J built for Houston looks nothing like one built for Dallas, and nothing like one built for El Paso. Our team produces ACCA-approved Manual J load calculations, Manual D duct designs, Manual N commercial load calculations, and Manual Q commercial duct designs calibrated to the correct climate zone and local code edition for your specific Texas job site (not a statewide estimate). Every report is delivered permit-ready to your inbox within 48 hours (see terms), as part of our nationwide service covering all 50 states.
WHY TEXAS HVAC CONTRACTORS OUTSOURCE THEIR CALCULATIONS!
SAVE MONEY.
Time is money. Every hour spent running load calculations in-house is an hour not spent meeting clients, closing bids, or installing systems. Outsourcing your Manual J, Manual D, and Manual S to our nationwide team frees up that time, and often costs less than doing it yourself once software and labor are factored in.
WORK SMARTER.
Running an HVAC business in Texas means knowing where your time is best spent. Manual J, Manual D, Manual N, and Manual Q calculations don’t have to be an in-house task,hand them to a dedicated nationwide team that does nothing else, all day, every day.
INCREASE EFFICIENCY.
Load calculations and duct designs are time-intensive and require ongoing software licensing and training. We use Wrightsoft, the ACCA-approved industry standard for both residential and commercial projects (serving contractors in Texas and all 50 states).
GROW YOUR BUSINESS.
If your business isn’t growing, it’s falling behind. Outsourcing your residential and commercial technical calculations to a dedicated nationwide HVAC service lets you focus on the field work that actually grows your Texas bottom line.
TEXAS HAS 5 CLIMATE ZONES. YOUR MANUAL J NEEDS TO REFLECT THE RIGHT ONE.
Texas is the only state in the contiguous U.S. that spans five distinct IECC climate zones — and the difference between them isn’t trivial. A load calculation built around the wrong zone means a system sized for the wrong climate, which leads to comfort failures, efficiency losses, and permit rejections. The 2018 IECC with Texas state amendments sets the statewide baseline, but local jurisdictions frequently layer on their own adopted editions:
Zone 2A (Hot-Humid): Houston, San Antonio, Corpus Christi, Beaumont — dominant cooling loads with significant latent heat contribution from Gulf humidity.
Zone 2B (Hot-Dry): Laredo, Del Rio, Eagle Pass — extreme sensible cooling loads with lower humidity. Radiant heat gain from solar exposure is the primary sizing factor.
Zone 3A (Mixed-Humid): Dallas, Fort Worth, Waco, Tyler — both heating and cooling loads matter here. This zone requires balanced calculations, not a cooling-only focus.
Zone 3B (Mixed-Dry): Midland, Odessa, Big Spring — high sensible loads, minimal latent, significant diurnal temperature swings.
Zone 4B (Cool-Dry): Amarillo, Lubbock, Panhandle — the only Texas zone where heating loads can rival or exceed cooling loads in an accurate Manual J.
Beyond the statewide 2018 IECC baseline, several Texas cities have independently adopted newer code editions: Austin enforces the 2024 IECC, Dallas has adopted the 2021 IECC, and Houston remains on the 2018 IECC. We track these adoptions and build every Texas report around the code edition your specific building department enforces, not the statewide minimum.
Texas also enforces a residential blower door standard of 5 ACH50 under the current energy code, which must be reflected in the design assumptions of a compliant Manual J. For contractors working with production builders or green certification programs, we also produce calculations aligned with HERS Index and ERI compliance pathways as alternative routes to energy code approval.
GULF COAST CONTRACTORS — TWIA WINDSTORM REQUIREMENTS
If your project is located in one of the 14 Texas Gulf Coast counties subject to Texas Windstorm Insurance Association (TWIA) jurisdiction — including Galveston, Nueces, Brazoria, Jefferson, Matagorda, Calhoun, and others — your HVAC permit package must account for windstorm construction requirements that affect envelope performance and, consequently, your Manual J load calculation. Our team flags TWIA county projects at intake and formats the report accordingly.
HVAC CALCULATIONS WE PROVIDE FOR TEXAS CONTRACTORS!
TEXAS MANUAL D
AC DUCT DESIGN SERVICE
FROM $259
Complete trunk and branch duct layout, register sizing, and static pressure report, calibrated to your Texas climate zone.
TEXAS MANUAL J
HEAT LOAD CALCULATION
FROM $109
Room-by-room or block-load heating and cooling load, ACCA 8th Edition compliant. Built around your exact Texas climate zone and local code edition.
TEXAS MANUAL S
EQUIPMENT SIZING
FROM $109
Confirms selected equipment matches your Manual J results — required alongside Manual J in most Texas permit packages.
COMMERCIAL HVAC CALCULATIONS FOR TEXAS CONTRACTORS!
TEXAS MANUAL Q
COMMERCIAL DUCT DESIGN
FROM $299
Trunk and branch duct layout, register sizing, and static pressure report for Texas commercial buildings.
TEXAS MANUAL N
COMMERCIAL HEAT LOAD CALC
FROM $299
Whole-building commercial heat load calculation for Texas light commercial projects up to 15 tons.
TEXAS
COMCHECK
FROM $299
Residential and commercial energy code compliance documentation accepted by Texas building departments statewide.
MANUAL D DUCT DESIGN FOR TEXAS HVAC CONTRACTORS
Manual D duct layout engineered for Texas climate zones, from Gulf Coast humidity to West Texas dry heat.
HERE IS HOW OUR TEXAS HVAC CALCULATIONS SERVICE WORKS
Delivered Quickly by Email — Texas and Nationwide
No matter where your job site is in Texas (or anywhere across our nationwide coverage area ) we deliver your calculations straight to your email inbox.
No wait, no hassle.
HVAC Calculation Services in Every Major Texas City
Nationwide service — delivered to your inbox from Houston to El Paso.
Our nationwide remote service means there are no geographic limitations, we support licensed HVAC contractors and general contractors anywhere in Texas, including these markets:
- Houston
- El Paso
- San Antonio
- Arlington
- Dallas
- Corpus Christi
- Fort Worth
- Austin
- Plano
- Laredo
No matter which Texas building department is reviewing your permit, we’ll make sure your Manual J, Manual D, and Manual S calculations, and your Manual N, Manual Q, and COMCheck for commercial projects; are formatted to meet their exact requirements. If your work takes you out of state, our nationwide team covers all 50 states with the same 48-hour turnaround (see terms…).
We Know Texas Building Departments
Permit-ready reports formatted for every jurisdiction — no rejected submissions.
Our team has produced permit packages for building departments across Texas. Here are direct links to the permitting portals for the state’s most active HVAC markets. Don’t see your county? Call us at 800-810-3280, we know them too.
IN A RUSH?
We Offer One-Day Expedited Service!
Our nationwide team understands that sometimes time is of the essence.
For an additional fee, we’ll deliver your done-for-you Manual D or Manual J calculation within one business day. Straight to your email!
What Contractors Are Saying
Professional, diligent, and efficient every time.
Dean J., HVAC Contractor
Fast, accurate, and they always hit the deadline.
Jake P., Engineer
Courteous, professional, and rapid service.
Mark K., General Contractor
PERMIT READY HVAC CALCULATIONS FOR TEXAS CONTRACTORS — NATIONWIDE SERVICE
Permit-ready documentation delivered to Texas HVAC contractors statewide and nationwide.
TEXAS CONTRACTOR FAQ
What energy code edition do your Texas calculations comply with?
Texas enforces the 2018 IECC with state-specific amendments as the statewide baseline. However, several jurisdictions have adopted newer editions independently: Austin enforces the 2024 IECC, Dallas the 2021 IECC, and Houston remains on the 2018 IECC. We confirm the correct edition for your specific building department before calculations begin.
What climate zone is my Texas project in?
Texas spans five IECC climate zones. Houston, San Antonio, Corpus Christi, and Beaumont fall in Zone 2A (hot-humid). Laredo and Del Rio fall in Zone 2B (hot-dry). Dallas, Fort Worth, and Waco fall in Zone 3A (mixed-humid). Midland and Odessa fall in Zone 3B (mixed-dry). Amarillo and Lubbock fall in Zone 4B (cool-dry). We build every report around the correct zone for your exact job site address.
What is the blower door requirement in Texas and does it affect my Manual J?
The current Texas energy code requires residential construction to meet a maximum air leakage rate of 5 ACH50 (air changes per hour at 50 Pascals). This infiltration rate is a required input in a compliant Manual J calculation. Our reports incorporate the correct blower door assumption for your jurisdiction.
Do you handle projects in TWIA windstorm counties along the Texas Gulf Coast?
Yes. We are familiar with Texas Windstorm Insurance Association (TWIA) requirements that apply to the 14 Gulf Coast counties under TWIA jurisdiction, including Galveston, Nueces, Brazoria, Jefferson, and others. We flag TWIA county projects at intake and format every report to account for the windstorm construction requirements that affect your building envelope performance and load calculation.
Do you support HERS Index or ERI compliance paths for Texas projects?
Yes. For contractors working with production builders, green certification programs, or clients pursuing alternative energy code compliance paths, we produce calculations aligned with HERS Index and Energy Rating Index (ERI) compliance pathways in addition to the standard prescriptive IECC path.
Do Texas building departments accept your Manual J and Manual D reports?
Yes. Our calculations are produced using ACCA-approved Wrightsoft software and follow Manual J 8th Edition standards, accepted by building departments throughout Texas, including Houston, Dallas, Austin, and San Antonio.
How fast can I get a Manual D for a Texas project?
Standard turnaround is 48 hours (see terms…) from receipt of all required project information. A 24-hour rush option is available for an additional fee — call 800-810-3280 to confirm availability.
Do you handle commercial HVAC calculations in Texas?
Yes. We provide Manual N commercial load calculations, Manual Q commercial duct design, and COMCheck energy compliance for light commercial projects throughout Texas.
Can I order Manual J, Manual D, and Manual S together for my Texas project?
Absolutely, and we recommend it! Ordering the full package ensures all three reports are consistent with each other and typically reduces the overall cost compared to ordering separately.
Is this service available to homeowners or only contractors?
This page is built specifically for HVAC contractors and general contractors. Texas homeowners working without a contractor should visit ManualJCalculator.com.
