The Condensation Challenge in Winter Construction

As construction projects become enclosed for winter, reduced ventilation and moisture from activities such as concrete drying, drywall finishing, and painting can create conditions for condensation. Even in heated buildings, warm, humid air can come into contact with colder surfaces, causing condensation that may affect building materials and construction progress.

Why Does Enclosing a Building Increase Condensation Risks?

Condensation occurs when warm, humid air comes into contact with a surface cold enough for water vapour to turn into liquid water. This happens when the surface temperature reaches or falls below the air's dew point, the temperature at which moisture begins to condense. During winter construction, temporary heating may maintain comfortable indoor temperatures while windows, structural steel, exterior walls, and other building components remain considerably colder. When warm, humid air reaches these surfaces, water droplets can form. The higher the indoor humidity, the higher the dew point, increasing the likelihood of condensation. This is why maintaining indoor temperature alone does not necessarily prevent condensation.

Where Can Condensation Occur, and Why Does It Matter?

Some signs of condensation are easy to identify, while others may go unnoticed until materials have already been affected. Common areas of concern include:

• Windows and glazing: Cold glass surfaces can collect condensation, particularly when indoor humidity is elevated.
• Structural steel and metal components: Repeated moisture accumulation can contribute to corrosion over time.
• Exterior walls and building assemblies: Warm, humid air entering colder assemblies can lead to concealed condensation, potentially affecting insulation, wood, and other moisture-sensitive materials.

If left unmanaged, condensation can damage finishes, structural components, and other building materials, potentially leading to additional drying requirements, rework, or construction delays.

How Can Construction Teams Reduce Condensation Risks?

Reducing condensation risks requires managing indoor humidity, surface temperatures, and the movement of moisture-laden air.

Control indoor humidity. Dehumidification removes water vapour from the air, lowering the dew point and reducing the likelihood of condensation on colder surfaces.

Consider the heating strategy. Temporary heating helps maintain indoor temperatures, but heating alone does not remove moisture. Certain heating methods, particularly direct-fired combustion heaters, can also introduce additional water vapour into the building.

Pay attention to air movement and building assemblies. Warm, humid air entering colder building assemblies can contribute to concealed condensation. Proper air barrier design, insulation, and moisture management help limit these risks.

Monitor changing conditions. Indoor humidity, outdoor temperatures, and construction activities can fluctuate throughout the day. Monitoring temperature, relative humidity, dew point, and surface conditions can help identify when condensation risks are increasing.

Remote monitoring and automated climate control systems can help project teams respond to these changes and maintain more consistent indoor conditions as construction progresses.

Keeping Condensation Under Control This Winter

As buildings become enclosed for winter, condensation risks should be considered alongside heating and interior finishing requirements. Understanding where condensation can develop and managing the conditions that cause it can help protect building materials and avoid unnecessary delays.

Contact our team to discuss a temporary climate control strategy that helps manage condensation risks throughout your winter construction project.

Source:

FPInnovations - Technical Guide for the Design and Construction of Tall Wood Buildings in Canada, Section 7.5.3 - Condensation Control.