Roseburg produces one of the most durable particleboard underlayment panels on the market today. Our UltraBlend underlayment is a premium-quality, mat-formed, multilayer wood particle panel. It is made of predominantly precision refined wood particles that are bonded with thermosetting resins. Ultrablend features a tight uniform core with machinable edges and excellent dimensional stability. UltraBlend underlayment particleboard is designed for strength and durability.