Fiberboard Curbside Trash Is It Treated Wood? If your fiberboard has been treated to prevent damage from rot and insects, it is hazardous waste. Dispose of it as treated wood. Untreated Fiberboard Is Garbage Small amounts of untreated fiberboard can go into your garbage. Large amounts must be taken to a landfill. Fiberboard Isn’t Recyclable or Compostable Due to the chemical adhesives used to make treated wood, it isn’t recyclable. The chemicals contaminate the wood recycling process and can add toxic chemicals to compost. Fiberboard May Be Carcinogenic A lot of fiberboard is made with urea-formaldehyde, a toxic substance and suspected carcinogen. Fiberboard will off-gas formaldehyde unless it is fully sealed. When handling, wear protective goggles and a respiratory mask and work outside or in a well-ventilated area. Never Burn Fiberboard Composite wood material is unsafe to burn because of the different chemicals in the adhesives used to seal it together. Ways to Reduce Don’t Expose to Water Unless your fiberboard has been treated to become moisture-resistant, don’t use it anywhere it’s likely to get wet (such as outside) and keep it away from water inside as well. Even a small amount of water can damage untreated fiberboard. Did You Know?