Medium-density fiberboard-Review specs and uses for MDF engineered wood panelsMedium-density fiberboard (MDF) is an engineered wood composite prized for its economy, strength, and consistently smooth faces and edges. MDF is widely used for painted and laminated cabinets, furniture, fixtures and workshop jigs.

    Medium-density fiberboard (MDF) is a composite wood product, similar to particleboard and hardboard. However, unlike other engineered-wood panels, MDF is extremely dense, very smooth, uniform, and highly machinable. It's made primarily out of waste softwood that's broken down into a fine powder, and then mixed with wax (for moisture resistance) and resin. The mixture is pressed under heat and pressure into dimensionally stable panels that are very hard and smooth as glass.

    Note that most MDF panels are made with resins that contain formaldehyde, a suspected carcinogen. Be sure to wear a respirator whenever you cut or machine MDF to avoid inhaling the dust.

    Medium-density fiberboard is typically used to build cabinets, furniture, doors, wainscoting and interior trim work. It accepts paint beautifully and is a near-perfect substrate for plastic laminates and wood veneers. MDF is used in the manufacture of laminate flooring, molded doors, fireplace mantels, prefinished shelving and primed moldings. Manufacturers of MDF include Temple-Inland, Niagara Fiberboard and Georgia Pacific.

    MDF: Panel Sizes and Thicknesses
    Standard medium-density fiberboard panels measure 4 feet wide by 8 feet long. Panels up to 9 feet wide and 18 feet long are also available. Custom sizes can be special-ordered from most manufacturers. MDF panels are available in thicknesses ranging from 3/16 to 1-5/16 inches, although a vast majority of panels sold are 1/2-inch and 3/4-inch thick.

    MDF: Basic Applications
    Medium-density fiberboard is used in place of solid wood and plywood in many woodworking, cabinetmaking and furniture-building applications. Its smoothness and dimensional stability make it an ideal material for cabinet doors, wainscoting, and paneling. MDF is typically finished with a coat of primer and two topcoats of paint. However, it's also used as a substrate for plastic laminate or wood veneer in the production of cabinets and furniture.

    MDF is often used to create custom interior trim work, including window and door casings, coffered ceilings, mantels, built-in wall units and paneled walls. The dense, uniform nature of medium-density fiberboard permits fine machining of crisp profiles and tight-fitting joints. When working with MDF, carbide-tipped saw blades, router bits and shaper cutters produce excellent results with minimum tear-out.

    Medium-density fiberboard accepts most woodworking glues, and is best fastened with straight-shank drywall or decking screws; standard wood screws have tapered shanks that tend to split the panel. Boring pilot holes prior to screwing helps reduce splitting. While screws are the recommended MDF fastener, good results are also achieved with hardwood dowel pins, compressed-wood biscuits, coated staples, and ring-shank nails.

    When compared to solid wood, MDF is less expensive, easier to work, more uniform and more dimensionally stable; it won't warp, check or crack. However, MDF is heavier than most solid woods, the edges will swell if they become waterlogged, and because it's so hard and dense, MDF dulls saw blades and router bits more quickly than does solid wood.

    Specialty Products
    A vast majority of MDF is sold in 4-by-8-foot panels, but it's also available in two ready-to-install building products: moldings and shelving. From casings and crown, to baseboard and chair rail, a wide variety of interior moldings and trimwork are milled from MDF. MDF moldings are typically primed and available in 16-foot lengths.

    Precut MDF shelving is available in sizes ranging from 12 to 24 inches wide and in lengths up to 12 feet. The 3/4-inch-thick shelving comes unfinished and ready for paint, or covered with white or woodgrain melamine. Both square- and bullnose-edged shelves are common.

    There are also a few specialty MDF panels worth knowing about:
    •Light MDF is 25 percent less dense than standard MDF, making it ideal for projects where overall weight is an issue.
    •Moisture-resistant MDF (often carries an MR designation) is designed for use in areas of high humidity or moisture. Use it to build cabinets for installation in baths, kitchens and laundry rooms.
    •Fire-retardant MDF is typically red in color and contains an additive that prevents it from igniting.
    •The newest type of MDF is specially formulated for use outdoors; see Extira Treated Panels. It's both moisture- and termite-resistant, and can be used for garage doors, column wraps, window shutters and many other exterior applications.

    Additional Resources
    Composite Panel Association