Mold growth on green lumber and in other building materials : an overview

In traditional construction defect cases, design and installation, product performance, and maintenance issues were the focus of complaints and/or litigation. Design and installation issues could involve leaks at penetrations in the building envelope, such as at a window. Infiltration of moisture at these locations would eventually result in decay in the adjoining wood and wood-based products (e.g., wood-based cladding, building paper, sheathing and framing). In recent years product performance issues have focused on the in-service performance of some wood-based composite materials, such. as hardboard siding and oriented strandboard (OSB) siding and sheathing. In these cases, the wood-based composite materials were alleged to be less durable than other wood products or alternative materials. Until recently, mold issues had generally played a minor roll in these cases. Construction defect cases have now begun to include a "personal injury' component, which has increased the requested settlement amounts in these cases. The health related effects of mold growth that has been routinely observed on green Douglas-fir framing lumber has also called into question. The purpose of this paper is to review the requirements necessary for the establishment and growth of mold fungi, discuss moisture movement in homes, and to summarize indoor air quality and related health issues surrounding mold growth on wood and wood-based products, with particular focus on the emphasis on the mold that routinely occurs green lumber.