Fiberboard sheet materials containing cellulosic fibers ae disclosed in which cellulose nanofibrils are used as a binder for adhering the cellulosic fibers together. The cellulose nanofibrils are present in an amount of 0.5% to 7.5% by weight on a dry weight basis of the fiberboard sheet. The fiberboard sheet materials have strength properties that meet or exceed the requirements in ASTM C208, and are useful for structural sheathing and roofing board applications. A process for manufacturing the fiberboard sheet is also disclosed.

Composite roofing structures can include mineral fiber roof cover boards with high concentration of mineral wool or mineral wool and perlite. The roofing structure may include: a roof cover board including a dried base mat including: 8-25% mineral wool, 40-65% perlite, 9-15% binder, 9-15% cellulosic fiber, and 0.25-2% sizing agent, all % by weight; an insulation layer; and a roofing membrane. The roof cover board is over the insulation layer, the roofing membrane is over the roof cover board. The roof cover board is attached to the insulation layer. The roofing membrane is attached to the roof cover board. Alternatively dried base mat may include: 30-70% mineral wool, 10-50% perlite, 5-15% binder, 2-20% cellulosic fiber, and 0.25-2% sizing agent. Alternatively the dried base mat may include: 60-90% mineral wool, 0-10% fiber, 0-10% perlite, 4-10% binder, 0-5% gypsum, and 0.25-2% sizing agent.

The present invention is directed to a fiber cement felt comprising repeat units, each of which includes top, middle, and bottom machine direction yarns and cross-machine direction yarns interwoven with the top, middle, and bottom machine direction yarns in a predetermined weave pattern. The top, middle, and bottom machine direction yarns may comprise effect yarns and linear yarns without the need for a batt layer.

A method may include pressing a mat including a blend of paper and plastic fragments by applying a pressure to the mat using a heated press such that the mat is compressed to a first thickness, where the pressure is greater than a critical pressure threshold such that at least a portion of a moisture content of the mat is in a super-heated liquid state. The method may include maintaining the pressure on the mat above the critical pressure threshold until at least a portion of the plastic fragments of the mat are melted. The method may include decreasing the pressure on the mat below the critical pressure threshold such that the mat expands to a second thickness greater than or equal to a target thickness, and such that the portion of the moisture content of the mat in the super-heated liquid state is converted to steam.

The present invention is directed to a fiber cement felt comprising repeat units, each of which includes top, middle, and bottom machine direction yarns and cross-machine direction yarns interwoven with the top, middle, and bottom machine direction yarns in a predetermined weave pattern. The top, middle, and bottom machine direction yarns may comprise effect yarns and linear yarns without the need for a batt layer.

Composite roofing structures can include mineral fiber roof cover boards with high concentration of mineral wool or mineral wool and perlite. The roofing structure may include: a roof cover board including a dried base mat including: 8-25% mineral wool, 40-65% perlite, 9-15% binder, 9-15% cellulosic fiber, and 0.25-2% sizing agent, all % by weight; an insulation layer; and a roofing membrane. The roof cover board is over the insulation layer, the roofing membrane is over the roof cover board. The roof cover board is attached to the insulation layer. The roofing membrane is attached to the roof cover board. Alternatively dried base mat may include: 30-70% mineral wool, 10-50% perlite, 5-15% binder, 2-20% cellulosic fiber, and 0.25-2% sizing agent. Alternatively the dried base mat may include: 60-90% mineral wool, 0-10% fiber, 0-10% perlite, 4-10% binder, 0-5% gypsum, and 0.25-2% sizing agent.

A roof cover board made from a mixture of 30-60% stucco; 20-50% perlite; 10-30% cellulose fiber; 3-20% starch; and siloxane. Also disclosed is a stucco-free roof cover board made from a mixture of 30-60% perlite, 30-60% cellulose fiber, 5-25% starch; and siloxane. Also disclosed are methods for making same.

A method may include pressing a mat including a blend of paper and plastic fragments by applying a pressure to the mat using a heated press such that the mat is compressed to a first thickness, where the pressure is greater than a critical pressure threshold such that at least a portion of a moisture content of the mat is in a super-heated liquid state. The method may include maintaining the pressure on the mat above the critical pressure threshold until at least a portion of the plastic fragments of the mat are melted. The method may include decreasing the pressure on the mat below the critical pressure threshold such that the mat expands to a second thickness greater than or equal to a target thickness, and such that the portion of the moisture content of the mat in the super-heated liquid state is converted to steam.

A roof cover board made from a mixture of 30-60% stucco; 20-50% perlite; 10-30% cellulose fiber; 3-20% starch; and siloxane. Also disclosed is a stucco-free roof cover board made from a mixture of 30-60% perlite, 30-60% cellulose fiber, 5-25% starch; and siloxane. Also disclosed are methods for making same.