Building Green: Energy Efficiency and Aesthetics From The Same Materials (Part 11)
The completed workshop, with its use of natural materials, blends in with the surrounding landscape. It helps to learn construction techniques on a very small green building before starting on a larger home.
Continuing with the construction of the workshop, the walls consist of adobe (mud bricks). The adobe work is very rewarding and the structure slowly rises from the earth in its finished form. We laid up to three courses of adobe per day. The height is determined by how fast the mud mortar hardens in order to support the weight of the adobes above without squeezing out under pressure. The mud mortar was a thick mix—about nine shovels of the premixed clay and sand to one gallon of water. This proportion will vary depending on the moisture content of the dry premix. For the workshop, the mud was mixed in a wheelbarrow. For constructing the larger home, we used an electric cement mixer that ran off the photovoltaic system. Except for the fact that my gloved hands got cold and wet, I preferred to use my hands for spreading the mud mortar to the proper thickness, as opposed to a trowel. Mud is very tactile and is a pleasure to work with. It is non-toxic, and unlike cement mortar, it does not have a limited working time before it sets up. The adobe is placed on the mud mortar and pressed into position. Mud oozes out the side and splats onto the ground. This mud can can be scooped up and used to fill the vertical spaces between the adobe blocks. The wall needed to be only about 5 feet in height as the pitched roof would give more than enough headroom. This is where a pitched roof is quite efficient in reducing the amount of construction time.
The eaves of the workshop are only four feet above the ground. This brings a human scale to the building and helps tie the structure to its surroundings. The landscaping also helps to blend the manmade elements with nature.
The rafters for the pitched roof were constructed of 2x6's that were then sheeted, tar papered, and finished with corrugated galvanized metal sheeting. Framing and sheeting a roof for a small structure like this was quite easy since the eaves were so close to the ground. Again, this is great practice before attempting to sheet a roof on a larger home, which is considerably higher.
Framing is very rigid. Everything is pounded, pried, and cut. The process is not very forgiving of inaccuracy. If a piece of wood is cut too small, it is discarded. If too big for the space, it must be cut again. Nails are pounded to hold everything together and the clatter echoes down the street. Everything is stiff, angular, and straight. This goes against my personal preference for more artistic freedom. I appreciate the softness and quiet assembly process of adobe. Walls are nudged into position, blocks are carved to shape. The process is quite intuitive and and the materials are malleable.
Visually, the frame roof on the adobe walls was not initially agreeable to me. The shapes of the precise metal roof atop the soft earthen walls were somewhat in conflict. A ridge cap detail on the roof could have helped. I would have preferred to have left the ends of the rafters exposed to add visual interest. A fascia board was needed to support the rain gutters for collecting water for the cistern. Framed structures can be quite beautiful. They just take more care and detailing to show the craftsmanship and the art. By the time the roof was finished, I looked forward to getting back to soft and pliable materials.
With time, the workshop settled into the landscape with the planting of vegetation and the assembly of the wooden doors with salvaged wood. I think a lot about landscaping when designing and building. In fact, some of the landscaping was installed during the construction. This permitted the structures to blend with the surrounding environment upon completion of the construction. I am very pleased with the end result.
Check back for more thoughts in the next article.
[This has been a guest post by Ted Owens, a green designer and filmmaker. More details on green building design and construction can be found on his website and in the Building with Awareness DVD and Guidebook. -Ed.]