Moisture Control Green Building
Moisture Control, Water Control, Green Building, Green Buiders, Energy-Efficient Homes, Green Houses
Moisture Control in Green Building
Understanding Water in a Green Home
|A green home is:
Water is not only the most important factor affecting a home’s durability, itis also the most important factor affecting the home’s maintenance costs andsustainability.
Jim Sargent, chosen by the U.S. Department of Energy as the Builder of theYear for his energy-efficient homes, tells his green building classes,"Homes last longer in dry areas. Moisture is the enemy. In fact, thebiggest enemy your house has is moisture. If a builder has a problem with thehouse, 99% of the time it is going to be water or water vapor related. If abuilder needs to be an expert on anything, it is water control."
Homes get wet during construction, during renovation or with age. The problem,though, is not that homes get wet but the solutions for moisture control. Homesneed a good drying system in place and it is important that they are dried asquickly as possible.
The concept of drying and the design of homes to dry is part of moisturecontrol. Moisture and its movement must be controlled from the beginning of thebuild job to the end of the home’s life.
There are several sources of moisture in the home. Themost important to control are below.
Sargent says, "Controlling rain is the single most important factor inthe design and construction of durable buildings and in the control ofmold."
Building physicist Joe Lstiburek takes it one step further and declares,"If you can’t control rain and ground water, it is senseless to go furtherin building a structure."
Sargent continues, "Homes must be designed with rain control for thelocation’s climate in mind. For example, we get an average of 39 inches of raina year in the Dallas-Fort Worth area. However, it does not come one inch hereand one inch there. We get most of the rain in short periods of time in thespring and the fall. Homes should be designed like we get 120 inches of rain ayear instead of 39 inches."
Other sources of water that need to be kept under control are:
These sources might have different significance in different climates (suchas snow in Dallas or snow in Minneapolis). The moisture sources and theirclimate significance must be considered when choosing materials for theconstruction of a home.
Climate significance must also be addressed when allocating resources formoisture control. For example, Minneapolis needs resources allocated for snowand ice damming control; North Central Texas does not.
Moisture moves by a number of means: capillary flow, vapor flow, airconvection, and gravity flow. Each of these mechanisms is driven by differentforces and moves at vastly different rates through different materials. Thisalso determines the choice of building materials for home construction.
Often walls get wet during the home’s construction from rain or otherprecipitation. Even if they don’t get wet then, they will get wet later fromother means–often from both the outside and the inside of the wall.Consequently, all walls should be designed to dry, preferably from both sidesbut definitely from at least one side.
Dealing with moisture is a very complicated subject for a builder tounderstand, much less for the general public to understand. And it is often evenmore complicated in a renovation of an older home. Choosinga builder who understands water and pays attention to water details is asimportant as choosing a builder who understands energy-efficiency.
There are two other aspects of water that must be considered in a green home.
1. Water conservation.
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