Many of the potential clients that I work with are very interested in the idea of straw bale. It is incredibly energy efficient, warm and beautiful to experience, and reletively easy and fun to build. And with a good design in mild climates, it is reletively maintanence free. Although, many people who don't live in mild climates are very interested in the value and uniquness of straw bale as well. I have had many folks from Ohio, Oklahoma, and North Carolina to Central America and Mexico wanting me to design a straw bale home for them. All of these climates have various degrees of humidity. It is true humidity and straw bales do not exactly go hand in hand. In fact, in a continual humid environment the bales have a very good chance of rotting and possibly producing mold. The actual figure for a bale to rot is about 17-20% moisture for an extended period of time. Typically, bales when stored properly by a supplyer or farmer come in at around 8% moisture. So with that, bales can handle quite a bit of moisture. I would guess more than most people would expect.
Moisure inside the house results from taking hot showers and baths, boiling water in the kitchen, washing dishes, exercising, ect. I think it is safe to say that all people do these things in homes all over the world. Sometimes these activities will cause the windows to fog up, or after extended periods produce molds. So why is it that some people have this problem and others don't? The answer is ventilation. Ventilation is the key to handling moisture inside the house. The best kind of ventilation is natural ventilation. With good design, it is possible to situate windows and doors in places that take advantage of prevailing winds and currents to literally flush air in and out of your house. Now this is all and good in climates and months when leaving windows open is an option. In very cold environments it would not be very practical to leave windows open to ventilate the house. There are several ways to remedy this problem. First is a dehumidifier. A dehumidifier is simply an air conditioner that has both hot and cold coils in the same box. A fan draws the room's air over the cold coil of the air conditioner to condense the moisture (which normally drips into a bucket). The dry air then passes through the hot coil to heat it back up to its original temperature. This is a good way to keep the inside of your home free of moisture. You can find dehumidifiers at any home store. Another option is a air exchange system. Air Exchange Systems are kind of like a dehumidifier but they do much more. Essentially they bring air from the outside (cold or hot) and replace it with air from the inside (cold or hot). In cases where the air is humid inside, it pulls the air out of the house and replaces it with air that has been dehumidified from the outside. So not only does it dehumidify the interior air but it replaces stale air with fresh air. There are many systems out there, although I specify The LifeBreath System by Nutech Brands Inc.
That's it for Part 1. I hope this helped in some way. In Part 2 I will talk about moisture from the outside and things that can be done, or not done, to work with straw bale design and construction. Thank You!