How Is Masonite Made?

What is Masonite?

Masonite is brand name for hardwood siding manufactured by the Masonite Company. This US-based manufacturer was one of the first companies to produce hardboard siding. After a series of class action suits in the 1980s and 90s Masonite discontinued siding manufacturing operations to focus on other products. Many other companies still produce hardboard siding however, and the material is still widely referred to as Masonite.

How Masonite is Made

Masonite, or hardboard siding, is made from wood scraps and sawdust. These materials are ground at high temperatures to produce long wooden fibers. The fibers are mixed with resin or adhesives and formed into soft mats. Heated plates are applied to the mats at high pressure, which transforms the material into a dense board with smooth outer surfaces. The boards may be embossed or finished to create wood grain or other patterns. These boards are then cut into 6' lengths that can be used as a siding material.

Installing Masonite Siding

Masonite siding is installed on the exterior of a home to protect against wind, rain, and other elements. It can be installed horizontally or vertically though overlapping horizontal rows are the most common application. After the building's framing system is complete, it is covered by plywood sheathing and some form of building paper or vapor barrier. The hardboard is installed starting at the bottom of the structure, and nails are used to fasten it to the framing system. Hardboard siding has a smooth surface that allows paint to adhere well and last for many years. Some varieties of hardboard siding may be pre-finished at the factory to save homeowners the trouble of painting the siding after installation.

References

• Oak Ridge Laboratory
• This Old House
• Composite Panel Association