You installed (or are about to install) a new HVAC system, filed for the permit, and the city sent it back. Somewhere in the rejection it asks for a "Manual J," a "load calculation," or a "heat-loss/heat-gain calc." If you've never heard those terms, you're not doing anything wrong — this trips up homeowners and even contractors every week.
What is a Manual J load calculation?
A Manual J is the industry-standard calculation (published by ACCA) that determines exactly how much heating and cooling a home needs — room by room — based on its size, insulation, windows, orientation, and local climate. It's the math that proves a furnace or AC is sized correctly for the house rather than guessed at.
It's usually paired with Manual S (confirms the equipment you picked matches the Manual J result) and Manual D (duct sizing). Many cities ask for the set.
Why does the city require it?
Texas adopts the International Residential Code (IRC) and energy code (IECC), and both require HVAC equipment to be sized by an approved method — Manual J is that method. The reviewer isn't being difficult: an oversized system short-cycles and wastes energy; an undersized one can't keep up. The load calc is how the city verifies the system is right before it goes in behind the drywall.
The most common reasons a permit gets rejected
- No load calculation submitted — the application went in without one.
- Equipment doesn't match the calc — installed tonnage doesn't line up with the Manual J / S.
- Missing Manual S or D — the city wanted the full set, not just the J.
- "Rule-of-thumb" sizing — a calc based on square footage alone, which most cities reject.
- Unstamped or unsigned — the city wants it from a licensed source.
How to fix it — fast
Get a proper TACLA-stamped Manual J (plus D and S if your city asked for them) and resubmit it. You don't redo your whole permit — you're adding the document the reviewer requested.
Cinch MEP does exactly this. We're a TACLA-licensed Texas HVAC contractor (license # 116156C), and TACLA-stamped residential load calculations are the entire focus. Standard turnaround is 3–5 business days, with same-day rush before 10 AM CT. You get a clean stamped PDF ready to upload to the city portal.
Stuck on a permit right now?
Send us the rejection notice and your project details — we'll tell you exactly which calcs you need and get them stamped.
DFW homeowners & contractors
We work the DFW cities every week, so we know each one's ePlan portal and what their reviewers ask for. See your city: McKinney, Plano, Frisco, Allen, Dallas, Fort Worth. Out-of-DFW Texas projects welcome at the same pricing.
Frequently asked questions
Do I really need a Manual J for a permit in Texas?
In nearly all Texas jurisdictions, yes — permitting a new or replacement HVAC system requires a load calculation by an approved method, and Manual J is that method. Square-footage rules of thumb are typically rejected.
How long does it take to get one?
Standard turnaround is 3–5 business days. Same-day rush is available for requests before 10 AM CT.
How much does a Manual J cost?
Residential Manual J starts at a flat rate, with the full J + D + S package available. See current pricing.
Can a homeowner order this, or does it have to be the contractor?
Either. Homeowners stuck on a kicked-back permit order directly all the time, as do contractors and builders.
What's the difference between Manual J, D, and S?
Manual J sizes the heating and cooling load. Manual S confirms the equipment matches that load. Manual D sizes the ductwork. Your city may ask for one, two, or all three.