Dealing With Moisture Control in High-performance Buildings
By Paul Brown, Construction Executive
Moisture control issues are surprisingly prevalent and occur in buildings regardless of the region. One U.S. Environmental Protection Agency building assessment survey and evaluation study found that 85 percent of commercial buildings had been damaged by water, and 45 percent of those had water leaks at the time the study was done.
Typically, a building suffering from moisture damage has a poor design that allows for weakness, faulty construction or failing materials, or improper building maintenance. Sometimes a combination of factors is in play.
HEALTHY MOISTURE CONTROL
While absolute dryness is ideal for the sake of building structural soundness and human health, it’s hardly attainable, nor should it be the end goal. Proper moisture control simply means that the building is dry enough that materials are kept adequately dry. Materials vulnerable to moisture damage should be kept completely dry and the building, in its entirety, should be designed to dry out quickly when too much moisture is present.
- With these guidelines in mind, healthy moisture control for every building is broken down into two major factors:
- The building should be designed in a way that water is not easily able to enter and condensation can’t easily form.
Rooms that have naturally high moisture levels (e.g.. bathrooms) should be ventilated and built to dry out as quickly as possible.
IMPACT OF MOISTURE CONTROL ON HEALTH
Aside from potential building damage, uncontrolled moisture issues that occur over long periods of time can cause side effects in those working within the building. These negative health effects include:
- difficulty breathing;
- exacerbated symptoms for occupants with asthma; and
- general upper respiratory ailments.
Though not as common in most cases, the Centers for Disease Control also reports some evidence to suggest that working in damp environments can cause:
- asthma development;
- shortness of breath; and
- lower respiratory disease (typically in children within school settings).
Not only is moisture control vital for maintaining a building, but it’s also vital for ensuring employee, staff and building occupant health. With regard to human health, it is the responsibility of the building owner to ensure that proper standards and protocol are in place to keep anyone within the building safe from unhealthy moisture levels.
When it comes to the building itself, a number of different types of damage can occur when moisture isn’t kept in check, such as:
- development of mold, fungus, and bacteria in building materials or within HVAC systems;
- insect and other pest damage;
- swelling, warping, rotting and overall damage to wood materials;
- degradation or complete failure of water-soluble materials (i.e., gypsum board);
- damage and peeling of paints, varnish and other surface treatments;
- potential chemical reactions with metal materials, including roofing, fasteners, wiring and coils;
- dissolved adhesives in roofing, flooring and wall coverings;
- cracking and general damage in concrete or brick during normal freeze-thaw cycles; and
- breakdown or weakening of insulation leading to a loss of energy efficiency.
Even materials considered to be extremely resistant to weather and moisture can still break down when not maintained. For example, metal is a common commercial roofing material due to its high durability, yet it can still corrode when water is allowed to pool or moisture is left unchecked.
MOISTURE CONTROL AND INNOVATIVE BUILDING DESIGN
If a building is being newly constructed, it must be designed in a way that allows for maximum moisture control, working from the exterior inward.
The building envelope serves as the first layer of defense from outside moisture; therefore, careful attention must be paid to the material choice. Insulated concrete block walls are an example of an excellent high-performance material that can be used for greater moisture control.
The overall building design must allow for effective control and removal of liquid water, as well as the purposeful use of more moisture-resistant materials in areas of the building where humidity levels or general water exposure may occur. Proper airflow and removal of water vapor, often with HVAC systems, must be in place to maintain healthy humidity levels within the building.
Moisture control in high-performance buildings comes down to smart design, quality materials selection and, perhaps most importantly, proper maintenance to remove water as soon as possible.