high-altitude attic frost melt saturated roof decking in boulder co - buyer requested $15k repair credit, how to remediate in 48 hours?

Question

selling our 2-story home in boulder co (chautauqua area). during the buyer's home inspection, the inspector found extensive black mold across the entire underside of the north roof decking.

the inspector noted that winter Stack Effect air leaks around recessed lights caused thick frost to form on the roof plywood, which melted during last week's spring thaw and saturated the insulation.

buyer is demanding a $15,000 credit or complete certified remediation with a passing lab test before closing in 5 days. how do we remediate and air-seal in 48 hours?

Antonio · Accepted Answer

Direct Answer:  You can completely clear attic roof decking mold and satisfy buyer reinspection within 48 hours using: (1) cryogenic CO2 dry ice blasting at -109.3°F under negative air, (2) EPA botanical antimicrobial sealing, (3) closed-cell spray foam air-sealing of all ceiling bypasses, and (4) third-party PRV air testing. 
 In Boulder's high-altitude climate (5,430 ft elevation), buoyant indoor air escapes into sub-zero attics, sublimating into thick rime frost. During spring warming, rapid frost melt drives timber moisture above 30.0% WME. Dry ice blasting sublimates instantly into gas, stripping fungal hyphae without adding moisture to cold wood framing. 
 The 48-hour Boulder attic clearance protocol: 
 
    Negative Air Containment:  Isolate attic hatch with 6-mil poly airlock and run HEPA scrubbers exhausting outside. 
    Cryogenic Dry Ice Blasting:  Blast CO2 micro-pellets at 300 PSI to strip mold roots off roof plywood. 
    Closed-Cell Bypass Air Sealing:  Seal all recessed lights and ceiling top plates with closed-cell spray foam. 
    PRV Laboratory Air Clearance:  Independent consultant collects air cassettes certifying Condition 1 clean ecology. 
 
 Call our Boulder emergency unit at  (855) 215-6261  for immediate dispatch.

jason_k_sea · Answer

Question for Antonio: Does the dry ice blasting process damage the roof shingles on the exterior side?

Antonio · Answer

No. The kinetic energy of dry ice micro-pellets at 300 PSI is calibrated to abrade only surface fungal hyphae and wood cellulose without penetrating through plywood decking or loosening exterior shingle nails.

danielle_w_appraiser · Answer

As an appraiser in Boulder County: The closed-cell spray foam bypass sealing is critical. It satisfies energy code requirements and proves to the buyer that frost will not reoccur next winter.

brian_t_gc · Answer

Make sure they also check that the bathroom exhaust fan is venting completely through the roof cap, not just blowing warm shower air into the attic.

jason_k_sea · Answer

Update:  Blasted yesterday, foamed the top plates, and routed the bathroom exhaust duct through the roof. PRV lab report was 100% clean!

jason_k_sea · Answer

Final Update:  Buyer withdrew the $15,000 credit demand once they saw the certified PRV lab report and warranty! Closing tomorrow morning on schedule!

high-altitude attic frost melt saturated roof decking in boulder co - buyer requested $15k repair credit, how to remediate in 48 hours?

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