DIY Cardboard Boxes for Insulation

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Things You'll Need

  • Mask

  • Safety goggles

  • Long-sleeved shirt

  • Utility knife

  • Hammermill

  • Large containers

  • Aluminum sulfate

  • Lime

  • Borax

  • Insulation blower

Cellulose insulation made from corrugated cardboard makes a good green solution.

You can save money by adding insulation to the attic and walls of your house. You can save even more money by making your own cellulose insulation out of shredded cardboard boxes. Finding and renting an industrial hammermill to grind the cardboard is more than worth the effort and expense when you consider the cost savings over buying commercial insulation. In addition, energy savings over the long term will more than make up for any initial investment. On top of everything, you will be helping to green the planet by recycling cardboard boxes that might otherwise go to a landfill.


Step 1

Put on a mask and safety goggles. Grinding cardboard boxes will create a lot of dust and you must keep it out of your eyes and lungs. It is also a good idea to wear gloves and long-sleeved clothing.

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Step 2

Remove tape, staples and any other foreign material from the cardboard boxes. Make sure the cardboard boxes are completely dry.

Step 3

Cut the cardboard boxes into strips and pieces small enough to feed into the intake hopper of a hammermill. Feed the cardboard box pieces into the hammermill. Collect the resulting shredded cellulose in large containers to keep it clean and dry.

Step 4

Mix aluminum sulfate with the shredded cardboard in the proportion of one part by weight to four parts shredded cardboard by weight. Aluminum sulfate will serve as an insect repellent. Since it rusts metal, if you use the insulation in a metal house or mobile home, use half the amount of aluminum sulfate and mix with the same amount of lime to neutralize this effect.


Step 5

Mix in one part borax powder by weight to 12 parts shredded cardboard boxes by weight. The borax will make the cellulose insulation fire proof.

Step 6

Install the insulation in the attic or walls of your house. Spread it manually in an attic or use a commercial insulation blower to install it inside walls. Make sure to keep the insulation well stirred so that the aluminum sulfate, lime, and borax stay evenly distributed.


You can shred newspaper along with the cardboard boxes in the hammermill. The resulting cellulose insulation will be the same. Cellulose insulation made from cardboard boxes and newspapers readily absorb moisture. Install it in locations where there will be no exposure to water or dampness. Owners of horses and other animals use shredded cardboard as a bedding material for their animals because of its low cost, insulating factor, absorbency and relative lack of dust.


Always wear safety equipment to protect your eyes and lungs from the dust generated by a hammermill. Wear them also when installing insulation.


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