Restorers should understand building systems and the related physical laws in order to restore a damaged building to its intended function and use-life. Building science addresses the materials and interrelated systems that create the structures in our built environment. Building science also addresses how buildings respond to different climatic environments. Climatic and regional variables include rainfall, temperature and relative humidity. Such variations may necessitate the restorer using different equipment and techniques when drying similar wet structures, in different regions or during different times of the year. [Note: Ad or content links featured on this page are not necessarily affiliated with The Clean Trust and should not be considered a recommendation or endorsement by The Clean Trust.]
A properly constructed building envelope acts as a physical separator between the interior of the built environment and the effects of outside climatic conditions. However, the actions of a restorer can force outside conditions to come into the built environment. The result can be either positive or negative with respect to the drying goals of a water damage restoration project.
It is complex and expensive for buildings to be constructed to function optimally in a single climatic zone during all seasonal conditions within a calendar year. Due to the variations within a single year or season, the building construction may be more or less appropriate with respect to prevailing ambient conditions. It follows that drying techniques will not be the same at all times of the year in all of these regions. Due to these varying climatic conditions, it is necessary for the restorer to combine science and art with professional judgment to successfully dry wet structures.
All building components are interrelated so that even a small change in one component can have a dramatic and potentially unexpected effect on the entire building. The interaction of these components affects the health and safety of the occupants, and the function and durability of a building.
Wall, Floor and Ceiling Assemblies
It is important for restorers to understand the construction of wall, floor and ceiling assemblies so as to facilitate educated decision making about drying and restoration. Knowledge of construction materials and their applications for strength, function, sound transmission and fire ratings all affect decisions as to how a building or structure can be properly dried and restored. Since all components of a building are interrelated, it is recommended that the restorer attempt to discern the intent of the design and construction of a building during a restoration project, and address those aspects individually and collectively during the drying project.
Elements of Airflow
It is important for a restorer to understand the elements of airflow in as much as it is a key transport mechanism for moisture. Because airflow is used as a tool in drying a building, it is recommended that restorers consider the complex variables of airflow that are created by their drying systems (open, closed and combination). For any given volume of air entering a building, an equal volume of air must leave. The type of building design and construction will influence where air will enter or exit, and how moisture can be controlled or removed.
All structures have planned openings (e.g., doors, windows, vents) and unplanned openings (cracks, crevices, gaps, material shrinkage, utility penetrations). Planned openings may be designed to either add or remove air from a building. If designed properly these openings do not compete for air. In order for air to move into or out of an enclosed space, such as a building or portion of a building, there must be an opening and a driving or pulling force. At times, these forces may be unexpected and potentially dangerous. Example: A dryer vent may pull air so strongly on the built environment that it causes the airflow from a water heater gas vent to reverse.
Caution should be used when blocking, sealing, or restricting airflow, or reversing the direction of airflow through a planned opening. Serious health and safety problems may result. If large amounts of air are drawn out of a building, the probability of combustion appliances back drafting or experiencing flame rollout is increased.
There are always unplanned openings in a building. If accompanied by a driving force, an unplanned opening can allow airflow into a building from garages, crawlspaces, attics or other air spaces. Driving forces, such as wind, heat/stack pressure, fans and duct systems, can affect the indoor environment and a building system.
Mechanisms of Moisture Flow
Understanding the four mechanisms of moisture flow is helpful in determining where and how moisture gets into a building, and is necessary when devising an effective drying plan. The four mechanisms of moisture flow are liquid flow (bulk water), air transport, vapor diffusion, and capillary suction.
The Effects of Moisture on Materials
In restoration projects restorers should be aware of the effects of moisture on building materials. Understanding how materials react to moisture allows the restorer to more adequately devise a drying system. How materials react to moisture depends on their moisture capacity, permeability, absorption and evaporation rates and their susceptibility to damage and microbiological growth.
Restorers should have a basic understanding of how a building envelope works and the interaction of the building assemblies in order to restore the damaged components to a pre-loss condition.
This information is quoted from the ANSI/The Clean Trust S500-2006 Standard and Reference Guide for Professional Water Damage Restoration, 3rd Ed. ©, pages 18 & 19, and is used by express permission of the copyright holder, The Clean Trust. No portion of the above excerpt can be duplicated without the written consent of The Clean Trust.
