How to Insulate Metal Buildings with Straw Bales

Figure up how many straw bales you need.

• 1

  Measure the length, width and height inside of the building. Lining the inside of a metal building requires exact measurements. It's better if you have extra straw instead of too little.

• 2

  Figure up the number of rows of straw bales you need. When you lay a straw bale on its side with the wrapped side of the string facing up, it is usually 18 inches by 2 feet wide by 3 feet long. Divide the height of the room by 1.5 feet for the number of rows of bales. If the ceiling is 8 feet tall, you need 5.3 layers stacked to reach the ceiling, so figure six rows.

• 3

  Divide the length of the two longest walls by three. Each straw bale is three feet long. If the room is 21 feet long by 20 feet wide, you need seven bales for the length of each long wall.

• 4

  Get the needed number of straw bales from the short wall by subtracting four feet from the length, and dividing the remaining number by three. The bales on the long walls are two feet wide, so it extends two feet on each wall into the space for the short wall. You need 5.3 bales on each short wall.

• 5

  Multiply the number of bales for the length of each wall by the number of layers for the height of each wall. For the long walls multiply, 7 times 6, and for the short walls multiply 5.3 times 6. Then add the totals for all four walls together. This room needs 147.6 bales, so round it up to 148 bales.

Insulating the Walls

• 6

  Spray a thin layer of foam insulation on the metal walls before insulating with straw. Rent an insulation foam sprayer, and spray a coating about 1/4-inch thick over anywhere the metal might touch the straw. Metal produces condensation, and the moisture causes mold in the straw unless there is a barrier. If you don't want a layer of foam insulation, leave a four-inch gap between the straw and the metal wall.

• 7

  Cut four pieces of 18-gauge wire five feet long for each corner of the room, and beside all doors and windows. These pieces hold the fence wire or chicken wire in place.

• 8

  Thread a piece of wire around the pole in each corner, so it is about 2 1/2 feet long on each side of the pole, if the building is a pole building. If it is a steel building, fold the wire in half, and make a loop in the folded end. Screw the loop into the corner wall. Pull the wire inward, so you reach it easily after putting the wall down. Place a piece of wire after every two rows of hay bales, and one piece of wire coming out the top. Attach pieces of wire with screws beside door openings and window openings at the same intervals.

• 9

  Start at end of one of the long walls. Place a bale of straw on the floor at the corner, so one of the 3 feet by 2 feet sides faces up. Push the next straw bale up against it tightly, and continue adding bales until the line goes to the end of the wall. If there is a door, add straw up to the outer edge of the doorframe.

• 10

  Place the next straw bale, so it makes an "L" shape on the short wall. Continue all the way around the room.

• 11

  Build the next rows by overlapping the straw bales like a brick mason hooks together bricks. Start the first straw bale of the second row on the first corner where you did the "L" shape on the short wall. Overlap the bale over the last bale on the first long wall, and the first full bale on the short wall. Continue around the wall. If an area is smaller than a whole bale, cut the excess off the bale with heavy scissors, and tie it tightly with twine. Alternate each row, so the straw forms a pattern like a brick wall.

• 12

  Place a piece of 1-by-12-inch wood across the bottom and top of window openings, and on top of doorways. The wood frames the openings, and makes them stronger.

• 13

  Cut the fencing material or chicken wire the length of the first wall. Thread the wires in the corners, by the doors and by the windows through the wire. Pull the wire tight, and twist the wires together forming a tight twisted knot. Continue cutting pieces, and wiring them on until all the straw is covered. This keeps the wall from falling inward.

• 14

  Cut off any straw that is sticking out past the wire. Use wire cutters, and cut wire covering window or door openings.

• 15

  Mix the stucco or plaster to manufacturer's instructions. Coat the inside walls with a thick coating of stucco or plaster using the trowel, and let it dry thoroughly. Once it's dry, paint it or leave it natural.