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Deck Mold Issues

Project Report > Inspection due to Water Intrusion from Deck

Moldy Deck Problems

Patio & covered porch below

Water damage and mold can cause all kinds of unwanted problems. Here is a case story of how exterior mold can ruin your deck and what you can do about it.

LOCATION: Lower Basement


  • Active leak noted from a plumbing supply line near the bottom of the stairway.
  • Good HVAC system and air filtration.
  • Sump pump present in the basement and appears to be functioning well.
  • RH:43 % Temp: 70°F CO2: 502 ppm CO: 0 ppm


Mold on my deck

Evidence of Failing Tile on Deck Above

  • Recommend having a plumber inspect and make repairs on leaking supply line.

 LOCATION: Crawlspaces

  • Recently deceased rat found in a trap in the back crawlspace. Very strong odor present upon opening crawlspace hatch.
  • Crawlspace under stairs reveals eroding soil from under the foundation. This is not likely a problem at this time but should be monitored to ensure further erosion does not occur.
  • Small Crawlspace at end of stairway shows some minor water intrusion from the foundation / footing cold joint. This does not appear to be a current problem.


  • Recommend having a pest inspector remove any dead rodents and re-set traps.
  • Recommend monitoring crawlspace for further moisture intrusion and/or soil erosion.



  • Significant amount of rodent feces, traps and carcasses present in the attic.
  • Ventilation fan from hall bathroom was not connected to roof vent.
  • HVAC ducts were not sealed or insulated.
  • Large open chases were present where relative humidity to enter into the attic space.
  • Insulation was not sufficient to meet current code.
  • Unsecured electrical connections were present in attic space.


  • Recommend installing new vent ducting from bathroom fan to roof and ensure it is connected securely.
  • Recommend removal and replacement of all insulation in attic space due to rodent contamination.
  • Recommend installing duct sealant on HVAC ducting to minimize air leakage into attic space.

LOCATION: Exterior


  • Tiled exterior porch off upstairs living room has failed and is letting significant moisture into the structure.
  • Severe staining and beginnings of rot were noted on underside of porch. It is not known how structurally sound the porch is at this time.
  • Gutters along back of home appear to require some maintenance.


  • Recommend having a contractor evaluate and make repairs to tiled porch on backside of home.

LOCATION: Master Bathroom / Bedroom


  • Deteriorated grout noted in master shower.
  • Failed sealant noted in corners of shower surround and pan.
  • Lower faucet has missing grout around the edges which may allow moisture to enter the wall cavity.
  • Good ventilation fan present in bathroom.
  • RH:45 % Temp: 69°F CO2: 541 ppm CO: 0 ppm


  • Recommend having grout in shower replaced.
  • Recommend running ventilation fan a minimum of one hour after bathing.

LOCATION: Upstairs TV Room


  • Peeling paint noted on upper corner of ceiling.
  • Increased moisture content noted in surrounding building materials.
  • Water damaged area appears to be a result of moisture intrusion due to a leaking gutter and no overhang. Wind may drive water leaking from gutter up into attic space and be affecting the ceiling.
  • RH:45 % Temp: 69°F CO2: 880 ppm CO: 0 ppm


  • Recommend having gutters repaired.
  • Remove all peeling paint from ceiling, sand and repaint to match.

LOCATION: Basement TV Room


  • Carpets in room are old and should be replaced.
  • RH:42 % Temp: 70°F CO2: 494 ppm CO: 0 ppm


  • Recommend removal of carpets from TV room and replace with a solid surface flooring such as hardwood, laminate or tile.
  • Client may wish to install an electric, in-floor heating system to allow for greater comfort.
  • Client may also wish to run a dedicated HEPA based filter in the room to help remove any additional particulate from the air.

LOCATION: Kitchenette


  • Leak noted under kitchen sink drain. No elevated moisture levels were noted at this time but repairs should be made prior to regular use of the sink again.
  • RH:42 % Temp: 70°F CO2: 499 ppm CO: 0 ppm


  • Have a qualified plumber make repairs to sink drain.

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