Construction Dryouts

Dry Buildings with Heat®

Today, many new structures are built with green or wet lumber that is high in moisture content. Materials delivered to or stored at a construction site during wet weather may not have time to dry prior to construction. Poorly stored timbers may collect moisture. When problems occur during construction as a result of inclement weather, high humidity, or other conditions resulting in vapor intrusion and condensation on structural members, contractors may use wet materials to expedite construction. As a result of any of these conditions, new construction with wet building materials is a serious problem that can end with unhealthy structures and damages from construction defects.

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Damages from Wet Construction Materials

According to the USDA’s Forest Products Laboratory, “Softwood lumber intended for framing in construction is usually targeted for drying to an average moisture content of 15%, not to exceed 19%.” Ultimately, construction lumber will reach equilibrium levels that reflect the local climate which may range from as low as 6% in desert areas to 12% in coastal regions. Shrinkage and warping occurs during the drying process. Timber that has a moisture content of 19% still has 30 to 50% shrinkage before it reaches equilibrium. It is important that framing materials are near equilibrium moisture levels before they are enclosed.

Framing timbers with high moisture levels can lead to improper seating of floor joists on sill plates leading to more apparent deflection, vibration and squeaking. Excessive shrinkage can lead to air leaking in walls, particularly around doors and windows. Windows and doors are frequently affected when construction proceeds using wet framing lumber. Wet lumber used to build roof trusses may lead to truss uplift resulting in ceiling stresses and deformation. Once the framing is enclosed, it is not possible to make corrections to these problems. These problems can be the source of many significant construction defect issues. Construction defects can allow moisture intrusion leading to health effects.

Health Effects from Wet Construction Materials

It is well known that damp structures are unhealthy structures. Newly constructed buildings may have fungal growth that occurred prior to or during construction. If this growth continues to receive adequate levels of moisture it can lead to both serious decay potential and an unhealthy structure. Mold problems may be found in structures that have never leaked because of these types of problems occurring during construction. A more serious problem can occur from building defects that resulted from shrinkage or warping of framing materials after the frame was enclosed. These types of problems can allow moisture to enter the structure from rain or even high humidity levels. There are many significant studies that illustrate the relationship between water damaged structures and health effects.

Damp Indoor Spaces and Health, published in 2004 by The Institute of Medicine, found a relationship between damp indoor environments and adverse health outcomes. This comprehensive review of literature found sufficient evidence of an association between damp indoor spaces and a variety of respiratory symptoms including upper respiratory tract symptoms, cough, wheeze, and asthma symptoms in sensitized persons.

More recent reviews of literature by the US Government Accountability Office (GAO, 2008) report, the World Health Organization report (WHO, 2009), the National Institute of Occupational Safety and Health (NIOSH), and the Lawrence Berkeley National Laboratory/EPA (Fisk, 2007) study provide additional support for these earlier conclusions and extend the concerns. The Executive Summary of the WHO report stated “Exposure to microbial contaminants is clinically associated with respiratory symptoms, allergies, asthma and immunological reactions.” Clearly, a relationship exists between damp structures and health effects.

ThermaPureHeat® is a Solution for Construction Dryouts

If high moisture levels are detected, application of the ThermaPureHeat® process after framing and sheathing can reduce moisture levels to 6-12%. The objective is to reach equilibrium moisture levels. If this process is complete prior to construction of vapor barriers and erection of sheet rock walls, mold will not colonize or amplify within the structure. Additionally, finish shrinkage will not occur to any great extent preventing both building and visual defects. It is important that the building’s frame reaches dimensional stability prior to enclosure to prevent significant additional shrinkage and warping. ThermaPureHeat® is an excellent preventive measure during the construction process. Additionally, structural pasteurization will provide other benefits in preparing the new structure for a healthy occupancy.

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