“Hello, We want to add two rooms to an existing small older home, my question is: We want to build a straw bale home with pallets on both sides, the thought is to put up the straw bales, then put on earth/clay/mud on the bales. As we put the mud on we will put a pallet up against the mud on each side and finish the wall, then once the mud is dry put adobe mud with straw [straw/clay] inside the pallets. This would create a very thick insulated wall. We live in North Dakota where it gets very cold and windy. Maybe we could put a somewhat flat roof so that it can be an earth roof with herbs. We will recycle rain water. Has anyone built walls in this manner? The room would be about 20ftx12ft Would this be sturdy enough to hold two story? There would be a partition wall in the center. We want to build being considerate of the environment and have little money. The pallets we are collecting free of charge just gas to pick them up. We would make our own mud/adobe and can get straw inexpensive, otherwise we will not be able to add on. We appreciate all the help you can give us as our funds are limited and work up here in the North is very little in the winter months and pay is not so good either.”
Owen: I like your idea very much. A straw bale/pallet wall will work for your purpose. One suggestion is to lay lengths of baling twine between the bales as you stack them and then later tie to the pallets. This will add a lot of strength. Be sure to raise the bales well off the ground away from snow and rain on gravel filled earthbags. And you’ll want to build a bond beam along the top of the wall to tie the whole structure together. If you do everything correctly, then I believe a 2nd story is possible, but only with careful workmanship and working out the details.
– It’s way faster and easier to use earthbags filled with gravel instead of tires.
– Brick on the outside is possible, but will greatly add to the cost unless it’s recycled.
– Typical living roofs are very heavy. Research thin, lightweight living roofs.
– Do not use a moisture barrier on the walls. Vapor must be able to pass through the wall.
– Build a strong bond beam as shown in the drawing and then you can add a second story. Insulate the cavity in the bond beam.
– Papercrete is prone to molding, especially in damp, cool climates. Do not use in your area.
– Add plaster mesh or chicken wire to the pallets, and plaster the walls. Wood siding is another option.
– Rainy areas create risk of the walls getting wet during construction. I suggest building a post and beam structure (pole building) first, then the roof and then the walls.