Study 2 Deck as a Mold Incubator

The owner (Milwaukee, WI) built an elevated—about 5 ft high—composite deck completely enclosed with the same composite boards, thereby creating a box perfectly insulated from any air movement. There were no windows in the box. The top of the box, that is, the deck itself, was pretty warm on a warm day, and rainwaters dripping into the box created a warm and very humid environment. The ceiling of the box, that is, the bottom side of the deck, was warm to touch from the inside of the box. After several months, the owner noticed small dark spots on the ceiling of the box, when she looked from the inside of her house through a small door, normally closed. There were no spots on the sidewalls of the box. 

A microbiologist that visited the place called it a perfect incubator for mildew. A microbiological analysis has identified two different types of fungi in the samples Alternaria alternata and Papulospora sp. (description is given below). 

The owner was advised to make a side window in the box. After two windows were cut, on opposite sides of the deck, mold disappeared rather soon. 

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