sweating attic ac flex ductwork caused ceiling mold in sarasota fl - how to remediate without replacing sheetrock?

Question

we live in sarasota fl. our central air conditioner flex ductwork in the unconditioned attic is sweating heavily due to 90% summer humidity, causing water droplets to soak through the ceiling drywall in our hallway and master bedroom.

black mold is visible around the ceiling registers and along drywall seams.

can this ceiling drywall be saved, or must it be replaced? what insulation rating is required on attic flex ducts in Florida to permanently stop condensation?

Antonio · Accepted Answer

Direct Answer:  Drywall with structural softness or microbial penetration exceeding 10.0 square feet must be cut and replaced under ANSI/IICRC S520 containment. To permanently eliminate duct sweating, Florida Building Code (Energy Conservation) mandates upgrading all attic flexible ductwork to  R-8 insulation  with continuous vapor barrier outer jackets sealed with mastic tape. 
 In Southwest Florida, unconditioned attics reach 135°F in summer with dew points above 75°F. When chilled 55°F air passes through older R-4.2 or damaged flex ductwork, outer vapor jackets reach the dew point, causing steady liquid condensation onto ceiling drywall. 
 The permanent remediation protocol: 
 
    Targeted Drywall Extraction:  Cut water-stained ceiling drywall under negative pressure containment. 
    Upgrade to R-8 Duct Insulation:  Replace compromised flex ducts with R-8 fiberglass insulated ducting sealed with UL 181 mastic. 
    Antimicrobial Register Sanitization:  Clean metallic register boots and treat surrounding framing with EPA botanical fungicide. 
    Independent PRV Clearance:  Pull air quality cassettes to verify clean indoor ecology. 
 
 Call our Sarasota emergency response unit at  (855) 215-6261  for immediate dispatch.

tom_w_sarasota · Answer

Thank you Antonio! Had an HVAC technician check our ducts and they were indeed old R-4.2 with torn outer wrap. Replacing with R-8 and having the drywall remediated tomorrow.

jennifer_realtor_fl · Answer

In Sarasota, R-8 ducts are mandatory. If you ever list the home, home inspectors check the duct insulation wrap stamps immediately.

sweating attic ac flex ductwork caused ceiling mold in sarasota fl - how to remediate without replacing sheetrock?

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