Archive for the ‘Germany’ Category
Wood and Clay; 2 great materials that go together.
Posted by Joshua | Filed under Breathable wall systems, Germany
Ahh, beautiful German architecture. The exposed timber frame, the lime plastered exterior, the clay tile roofs. Most of these homes were built between 200 -350 yrs ago. Some have been maintained well, others are falling apart and others have been maintained using more modern methods.
What is regular maintenance on the homes? New earthen plaster every 20 yrs or so, where necessary, a new coat of lime plaster every 100 yrs, a coat of lime wash on the exterior every 5 yrs. Straw replacement under the tiles every 100 yrs (more about this later in a post on roofs).
Not very much.
So, this is a great picture I pulled from Wikipedia that shows typical wall construction. Exposed timber frame. Oak splits, inserted into the frame and willow wound through the oak staves creating what is called the wattle of wattle and daub. The daub is what is called cob in the U.S.; a mix of clay, sand and straw. Pushed into the wattle. And then earthen plaster on the interior, lime plaster on the exterior.
The other method of infill can be seen at the top of the picture. Take clay bricks, otherwise known as adobe, and use an earthen mortar and in throw it all in. And if you have access to stone, use that instead.
All of this results in a breathable wall system. One that allows moisture to get out of the wall. This is incredibly important for the health of our homes and ourselves.
Hopefully, we will start to see more of this style of construction in the U.S.
Lehmbau Regeln, Germany’s earth building regulations
Posted by Joshua | Filed under Germany
Lehmbau Regeln is Germany’s codes for earthen construction. These codes have been existant since 1998. Although not accepted by all states within Germany, it is widely recognized and used. Although the context is different, there is much with these regulations that is applicable to our country. Lehmbau Regeln can also be used as an educational instrument for our dear friends at the building division.
So, about 4 years ago, a grant from Portland’s Office of Sustainable Development’s G-Rated program was awarded in order to translate this book. A rough translation was made. Unfortunately, it never went beyond that. I was able to secure a copy of the translation and not being able to sleep on the plane, I read the translation. I also started to provide some changes to it in order for it to be more readable and consistant with our U.S. terminology. At theconference, I talked with Kurt Gardella from Northern New Mexico College’s Adobe Construction Program. Being fluent in both German and English, as wel mas being familiar with earthen construction, he is ideal for helping further streamline the translation. Then it can be made more accessible to those who would like to learn more about the German techniques, or would want to use it with their building departments.
At Lehm ‘08, they released the 10 yr updated version and discussed the changes that were made. I now have a copy of the updated version and at some point will be taking a look at what it is that have changed.
What’s in the Lehmbau Regeln? Well, it gets broken down into three parts: soil testing, which soils are appropriate for which techniques, and the earthen buildiding techniques.
In Germany, they require three tests, tensile strength, plasticity and particle size distribution, or the gradient as it is sometimes called. I don’t have the picture of the apparatus for tensile strength, so I’ll include that in another post. The other two tests are done in the lab. The tensile strength test is the most important. It determines what you can and can’t use the soil for.
It reviews the following types of earthen construction: rammed earth, cob, poured earth, light straw clay, light woodchip clay, light pumice clay, a material that is halfway in between light straw clay and cob, adobe, unfired brick, light straw clay bricks, wattle and daub, exterior lime plasters interior earthen plasters, and clay panels (think the clay version of sheetrock). I am not going to go through these right now, but may tackle them one at a time. But those are other posts.
If you want to know anything more specific, or want a copy for help with a current project, e-mail me.