Once we had the straw bales placed it was time to start the plastering. Over a period of two weeks we had 6 men spreading two coats of this mortar mix over the straw. It was quite a process particularly when we had to deal with temperatures dipping well below freezing half of the time. The last thing you want to have happen is for the water in the mortar to freeze. This leads to cracking and poor adhesion to the straw. It was also a problem having to deal with waterhoses that kept freezing on us.
The mortar was a careful mix of cement sand and fibreglass. Unlike ordinary sand which is rounder in shape, cement sand is angular and has more surface area which improves the bonding. The fibreglass strands were added to reduce cracking which can occur as the mortar dries and shrinks. In all, the mortar added another inch to each the inside and outside walls. Once cured, the walls in combination with the straw, become a strong, stable unit.
Unlike traditional walls today, there is no vapour barrier in a straw wall. This allows them to "breathe" and the cement tends to wick any moisture out and away from the straw. The air inside a straw home is very clean and without the vapour barrier there isn't the same worry about harmful gases being trapped inside. Even so, the materials used inside Chinook are all natural including all of the floor and wall finishes.
The next step with Chinook is to bring power and water into the building and then begin the interior finshing. We still have the soffits and some siding to do on the outside but all of the main work is now done.
