From this site

One project, every trade

Each calculator adds its lines to a single estimate — consolidated BOM, schedule and cash-flow included.

Open My Project →

Curtain Wall Spandrel Condensation Risk Checker

Check whether a curtain wall spandrel's interior glass surface temperature stays above the dew point under winter design conditions.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-27 · v1.1.0

Market
Imperial · sales tax

Interior glass surface temperature

57.25 °F

High confidence

PASSES — the calculated interior glass surface temperature (14.02°C) stays above the interior air's dew point (10°C), so condensation is not predicted under these steady-state design conditions. This checks room-side vision/spandrel glass surface condensation risk only, per NFRC 500/AAMA 1503 steady-state methodology. Shadowbox CAVITY condensation — a distinct, common failure mode driven by trapped cavity moisture and solar vapor drive behind the spandrel panel — is NOT covered here and needs separate ventilation/vapor analysis per GANA/NGA guidance.

Interior air dew point
50 °F

At the values currently entered, the interior glass surface temperature works out to 14 °C. The largest intermediate quantity is interior air dew point, at 10 °C — check that step first if the total looks off. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Steady-state condensation risk check per AAMA 1503/NFRC 500 methodology: interior surface temperature Ts = Ti − U×(Ti−To)/hi, where Ti/To are interior/exterior design temperatures, U is the assembly's overall U-factor, and hi is the interior air film coefficient (commonly 8 W/m²K); condensation risk exists if Ts falls below the interior air's dew point

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

What does this calculator actually check?
It estimates the steady-state interior glass surface temperature of a curtain wall spandrel or vision glass assembly under winter design conditions, using the NFRC 500/AAMA 1503 methodology, and compares it against the interior air's dew point. If the surface temperature falls below the dew point, condensation is predicted on the room-side glass surface.
Does passing this check mean the spandrel panel is free of condensation risk everywhere?
No. This checks room-side vision glass surface risk only. Shadowbox cavity condensation — moisture trapped behind the spandrel panel, often driven by solar vapor drive — is a separate and common failure mode that this tool does not evaluate. That risk needs its own ventilation and vapor-drive analysis per GANA/NGA guidance.
Where does the interior film coefficient value come from?
8 W/m²K is a commonly used interior air film coefficient in this type of steady-state check, but actual values can vary with air movement near the glass (e.g. from HVAC diffusers or blinds). Use a project-specific value if one has been established.