/ Field knowledge · IMC 604.13
Do not line the wet coil discharge.
IMC 604.13: exposed internal insulation that is not impermeable to water cannot run from the cooling-coil exit to the downstream end of the drain pan. Generic lined duct through that section is the comment — and the mold later.
Educational 2024 IMC 604.13. Confirm adopted edition. This is not an insulation specification. Internal insulation exposed to the airstream needs a UL 181 durability basis.
- Locate the cooling-coil discharge and the downstream end of the drain pan.
- Trace every exposed internal liner in that segment.
- Verify product impermeability and the UL 181 durability basis.
- Show the lined-to-unlined transition on the plan or detail. Confirm equal thermal performance where the liner is interrupted.
Liner through the drain pan
If a superintendent can stand at the coil discharge and still ask where the pan ends, or whether the exposed liner is water-impermeable, the drawings are not clear enough. Wet liner is an IAQ problem that comes back after remediation if the root cause stays.
Source: DCT 604.13 · insulation: 604 · condensate: 307.
What to send
The AHU / coil section and whether the downstream duct is shown lined.
If the liner runs through the coil discharge
Send the AHU section. Masterbuild will say whether 604.13 even allows that product — or the drain-pan limit was never drawn.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
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