Wall Condensation Construction Claims Expert Overview

When water damage is found in a wall, an exterior leak is often assumed; however, condensation should also be considered. This article explores the design standards for mitigating wall condensation and the process by which a forensic investigator can determine if damages were caused by condensation due to deficiencies in design, construction, maintenance, or some combination thereof.

How Condensation Forms Within a Wall

Warmer air has the capacity to contain more water content as humidity than colder air. As the temperature of air drops, humidity condenses out of the air and becomes liquid water. The term “dew point” describes the temperature (based on specific atmospheric conditions) at which moisture from the air will condense on surfaces. This effect is regularly observed on the glass of a cold drink on a hot day but can also occur within the walls of buildings and other structures.

In a climate-controlled building, the temperature of the exterior wall materials will change within the thickness of the wall. If, for example it is 30 degrees outside, and the building is heated to 70 degrees, the inside face of a well-insulated wall will be about 70 degrees, and the outside face will be about 30 degrees. The various components of the construction within the wall will vary in temperature between those two extremes.

If a wall component’s temperature falls to the dewpoint or lower, liquid water can condense out of warm, moist air within the wall. Often that temperature point falls somewhere within the thickness of the wall insulation, where the majority of the temperature transition occurs. When this happens in porous insulation like fiberglass or cellulose materials, the insulation can become wet. If there is no insulation, the water can condense on the inside surface of exterior sheathing or siding materials.

Design Standards to Control Condensation

Standard practice requires that wall systems be designed to either limit condensation or to control where condensation occurs so it does not contact wall components that may be damaged by water.
One means of limiting condensation is the inclusion of a vapor resistive barrier on the side of the wall where the more humid conditions are expected. In most of the US, that is on the interior face of the wall, directly below the drywall. In the Southeastern US, the exterior is considered the humid side, and the vapor barrier should be placed on the inside face of the exterior finish. The vapor resistive barrier is a membrane or coating which greatly reduces the passage of water vapor into the wall construction. The reduction in passage of vapor through the barrier reduces the amount of water vapor that can condense into liquid water.

Plastic sheeting is commonly used as a vapor barrier. Other materials are used as vapor barriers or vapor retarders for the same purpose. To effectively limit condensation, the vapor restrictive barrier must be continuous, and be properly terminated at the edges of the wall, including at the floor, roof, windows, and at other openings, such as electrical boxes.

Walls can also be designed to manage condensation by directing accumulated water to the exterior of the building, away from moisture vulnerable materials. Many types of exterior walls are designed to manage water that is likely to penetrate or leak through the exterior finish by incorporating a weather resistant barrier. (“Tyvek” is a commonly known product that performs this function.) Water that penetrates to the weather resistive barrier is prevented from entering the building and is directed through a vertical cavity in the wall construction to the outside of the building by flashing and other means.

Weather resistant barriers are common on walls with brick exteriors. Walls with brick exteriors typically include an open airspace behind the brick to allow any water which penetrates through the brick to drain out of the building. A weather resistive barrier is installed on the inside face of the cavity. To manage condensation in that type of wall system, the insulation is placed on the exterior side of the weather resistive barrier. Any condensation that occurs in the insulation will drain into the cavity and be directed to the exterior through the same system that manages exterior water infiltration. In this type of system, the insulation must be unaffected by moisture.

The use of solid closed-cell foam often installed using spray techniques is another strategy for controlling vapor and condensation. The closed cell foam restricts air or water transmission. So long as the dew point is within the thickness of the foam, condensation problems will be minimized.

Determining Liability in Water Damage Claims

Specific building materials and construction methods will vary based on the age, use, and location of the property. To understand the cause of water damage, the exterior wall must be analyzed as a complete system, rather than the individual components. Robson Forensic offers experienced construction professionals throughout the country who can assist in the resolution of these disputes.

For more information, submit an inquiry or call us at 800.813.6736.

Featured Expert

Anthony Fenton, AIA, RRC, REWC, ASCA-C, CXLT

Architecture, Construction & Premises Safety Expert

Anthony Fenton is an architect with 25 years of diverse professional experience in building design, renovations, and construction administration. His career prior to joining Robson Forensic covered a… read more.