Architect Air and Moisture Control Concerns
Air and moisture control is important for occupant comfort and structural durability. Architects have to consider moisture control during the planning and construction phase of any building. There are several ways for moisture to travel into a building. In addition to precipitation and natural humidity, moisture can get into buildings from construction moisture, ground moisture, or it can be introduced from mechanical equipment or internal sources.
Construction Moisture
Construction moisture may be unavoidable. Concrete mixes require large volumes of water. It may take years for a concrete structure to fully dry out, so builders must plan to accommodate that source of moisture.
Barriers and proper drainage have to be employed to isolate the building from ground moisture. Vapor barriers under concrete slabs can help keep ground moisture from migrating upward into structures. Proper footing drainage at the perimeter of the building allows moisture and rainwater to be directed out and away from the foundation.
All of the internal sources of moisture have to be considered. Commercial kitchens, lavatories, fountains, plant life, washing maintenance and other internal sources combined can represent a significant moisture danger.
Moisture Control Depends on Climate
Climate variables have to be carefully considered in the design of building envelopes. Climate-zone maps provide vital information that should be considered in the design of buildings. Climate zones require different concentrations of heating or air conditioning systems, each of which have their own moisture control problems. Moisture control strategies must fit the climate and the microclimates in the building area.
Walls, structures and building envelopes must be assembled with moisture in mind. Installing building envelopes that do not protect the structure against moisture appropriate to the region can be an expensive mistake.
Possible Building Envelope Defects
Before construction, architects must consider the possible building envelope defects so that they can combat them.
- Product failures or temperature/moisture conditions that exceed product limits can cause building envelope faults or defects.
- Barriers may be installed without accounting for a building shift over time. These shifts may leave holes, tears, or parting of the envelope material.
- Sometimes chemically inappropriate materials are matched together in the construction of a building envelope. This can cause the material to harden, become brittle and crack or otherwise degrade.
- Sometimes designs rely too much on sealants in construction. When the sealants fail, the building envelope is compromised.
- Non-destructive testing methods can be used to detect poorly operating building envelope elements that allow moisture penetration. Infrared thermography and portable nuclear gauges can be used to detect moisture trapped in roof or wall assemblies.
Understanding moisture control is key to a structure’s longevity. From start to finish moisture control should be a priority. Installing the proper building envelope varies from project to project, but if done properly, the structure will be sound for years to come.
For more information on moisture sources in the home, check out this Group EnvironeX article.
