Roof Heat Loss Calculator
See how much heat your attic is losing through the roof — and what it costs you every winter. Based on the honest physics of Q = U × A × dT, the same steady-state conduction math engineers use for building heat-loss design.
How the math works (no tricks)
Heat flows from your warm home into the cold attic at a rate of Q (BTU per hour). The resistance to that flow is your insulation's R-value — higher R means slower heat loss. Thermal transmittance U is simply 1 divided by R. The bigger the attic area (A) and the bigger the indoor-to-attic temperature difference (dT), the more heat escapes.
Q = U × A × dT = (1 ÷ R) × area × temperature difference
Annual cost is estimated from your 3,000 heating degree days (Tulsa's typical winter severity): seasonal heat loss = Q × 24 hrs × 3,000 HDD ÷ dT. That seasonal total is converted to dollars at $0.12/kWh (electric resistance) or $1.20/therm at 80% AFUE (natural gas furnace).
Your Attic
Adjust the sliders and fields — results update instantly.
Use the heated floor area directly below the attic. A typical 1,500 sq ft single-story Tulsa home has roughly a 1,500 sq ft attic floor. Default 40°F — a typical Tulsa winter delta between a 65°F home and an ~25°F average outdoor temperature. Air leaks and ceiling penetrations add real heat loss on top of conduction. The multiplier is an honest estimate — drafty attics lose more.Your Heat Loss
Steady-state conduction through the attic assembly.
Heat escaping through your attic right now, on an average winter day.
R-Value Upgrade Recommendation
What each insulation upgrade would save on your current attic. Rows only show targets above your current R-value.
| Target R | Added insulation | New heat loss | Est. annual gas cost | Est. annual electric cost | Est. savings vs. current | Est. install cost | Gas payback |
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Want a Professional Look at Your Attic?
Proof Construction — serving Tulsa since 2015, Owens Corning Preferred, CIB #80004070, 4.9★ from 127+ reviews. Get a free roof inspection that includes an attic insulation assessment.
(918) 734-4444 Get Your Free EstimateAttic Heat Loss FAQs
How much heat does an under-insulated attic really lose?
Attic heat loss follows a simple physics rule: Q = U × A × dT. Q is heat lost in BTU per hour, U is thermal transmittance — 1 divided by your insulation R-value — A is the attic floor area in square feet, and dT is the temperature difference between your heated home and the attic in degrees Fahrenheit. A 1,500 sq ft Tulsa attic at R-19 with a 40°F winter temperature difference loses about 3,158 BTU per hour — roughly 5.7 million BTU over a 3,000 heating-degree-day season. Raising that attic to R-49 cuts the conduction loss by more than half.
What attic R-value does Tulsa building code require?
Tulsa is in IECC Climate Zone 3A. The Oklahoma energy code (IECC 2015 as amended) requires R-38 for new attic construction — that is the legal minimum for new homes and additions. For existing homes, the U.S. Department of Energy recommends R-49 for attics in Zone 3, and many Tulsa homeowners choose R-49 or R-60 because the extra cost is small relative to the energy saved over the 20-30 year life of the insulation. Proof Construction assesses attic insulation as part of every roof inspection and can add blown-in fiberglass or cellulose to bring your attic up to standard.
Is it worth adding attic insulation in Tulsa?
On conduction math alone, upgrading a 1,500 sq ft attic from R-19 to R-49 saves roughly $50-$70 per year in natural gas heating (about $120-$140 per year for electric resistance heat). With blown-in insulation typically installed at $0.05-$0.10 per square foot per R-value, that upgrade runs about $2,200-$4,500 and pays back over several heating seasons — and the insulation keeps saving for 20-30 years. Older homes with R-13 or less, drafty attics with air leaks, or homes heated with electric resistance see the biggest savings. Because air leaks can carry more heat than conduction, pairing insulation with air sealing multiplies the benefit. This calculator is an educational estimate, not a professional energy audit.
Should I add insulation or replace my roof first?
They solve different problems. Attic insulation directly lowers your heating bills — it is almost always the better first step if your roof is still sound and your energy costs bother you. A roof replacement is driven by storm damage, leaks, or end-of-life shingles, not energy bills; asphalt shingles add little insulation value. The exception is a vaulted or cathedral ceiling, where insulation is installed in the rafter bays and a roof replacement is the right time to improve it. Proof Construction offers free roof inspections and attic assessments across the Tulsa metro — call (918) 734-4444.