A local lumber yard was experiencing an unusual problem of mold growing on their wood trim and molding products which were stored under cover in an unheated storage area.
Investigation: The lumberyard storage area is a three sided structure such that exterior air freely infiltrates the area. The location is in an area where fog is a frequent occurrence and the lumber is subject to 100% relative humidity conditions. On these occasions moisture will condense on the lumber and provide the right conditions for mold growth.
Recommendations: Enclose the wood trim storage portion with a fourth wall, building it as tight as possible. Pipe in a continuous supply of conditioned air from the adjacent office space. This will produce a small a positive pressure condition in the storage shed, keeping moist exterior air out and prevent mold growing conditions from occurring.
Results: A fourth side to the enclosure was built preventing a free flow of outside air to the lumber. An in-line fan was installed to bring interior air to the enclosure and maintain a positive pressure to prevent moist foggy air from entering. Moisture no longer condenses on the lumber.