The timber-frame chicken coop saga is coming to an end. The last update showed much of the work through plastering. This can also be seen in video form here. Since then, the plaster has been finished, clapboards wainscoting went on the bottom, and the whole structure has been coated in whitewash or linseed oil.
When rain falls, it hits the ground around the coop, splashing mud up on the lower foot or two of the structure. Over time this would be hard on the timber frame as well as the plaster, so I decided to add clapboard wainscoting around the bottom. Because this would be wood dealing with moisture, it needed to be protected somehow. I had recently heard about a Japanese treatment that charred the outside layer of wood. Yakisugi (often called shou sugi ban, which is a misreading of the kanji) means “fire-heated cypress” and refers to planks that are charred on one surface. Carbonization removes the organic elements that microorganisms eat, so when the burned surface gets wet, it is less likely to rot.
The traditional way burn these planks is to tie three boards into a triangular tube, stuff it with kindling, stand it up, and light the bottom. As the fire burns up, it chars the wood. Unfortunately, I found this way difficult to control and the cedar I did this way had uneven burning patterns. I ended up starting a campfire, spreading it out, and then moving boards over the burning coals to char the surface. This way I could monitor the burn and give it a more even treatment.
After burning, these boards were gone over once with a stiff wire brush to remove the most charred bits (although some applications leave these on). Next I installed them like typical clap board on the lower portion of the structure. The most heavily charred planks went on the bottom, where they’ll be wetter than the lighter ones higher up.
The boards went on after the second layer of plaster. The third layer was then applied above the boards and smoothed flush to the top of the yakisugi boards so that water runs down and off, rather than slipping behind.
Finishing the Plaster and Whitewash
The final coat of plaster was 1 part lime putty and 1.5 parts fine sand. I tried to keep this as dry as possible to avoid cracking. Unfortunately I am not an expert mason, and I had some minor crevasses in the exterior coat of plaster. I used a trowel to fill them in with more of the same plaster, which gave the surface a blotchy appearance.
This was soon alleviated by whitewash. Many people think of whitewash as cheap white paint, but it is actually watered down lime putty and forms not a latex layer (like most modern paints) but a geological one, where calcium hydroxide (Ca(OH)2) reacts with carbon dioxide to form a layer of calcium carbonate (CaCO3). The crystals catch and refract light, making the surface a dazzling white when the sun shines on it.
My whitewash was made by adding 1 part lime putty to 8 parts water and mixing until dissolved. It was the consistency of milk. When first applied, it looks clear, but after it dries and cures, it becomes more opaque. I applied about five coats to the exterior and interior.
The chicken door is a weight-sensitive one and designed for a heavier predator to tip the door closed as it tries to enter. To close the door, it is tipped down and held in place with a dowel between two eye hooks.
The coop is ventilated through big openings on the front and back as well as smaller gaps between the rafters on each side. Each one is covered with a mosquito netting and 1/4-in hardware cloth secured to keep predators out. During the winter, the big vents are closed by doors that drop down from the ceiling to block gusts of wind. Straw is added to reduce drafts and add some insulation.
The interior of the coop is not very exciting, but contains water and food suspended from the ceiling as well as a roost and lay boxes.
The wood was covered with a layer of boiled linseed oil. The yakisugi boards really soaked up the oil and require a few passes. The timber exteriors turned a deeper shade of their original color. Once done, I realized that the coop matches the white, black, and tan of our Swedish flower chickens. One is mostly black and white, but the more colorful one has turned out to be a surprise rooster.
A video will be coming soon.