When it comes to flush door construction, the common manufacturing process is to create a five-ply product—a central core is one of the plies that is then covered on each side with two other plies—a crossband substrate layer and then the selected wood veneer. All four exposed edges of the core are covered with an internal set of supportive stiles that can have a smooth edge treatment that can be specified to match the door. Similar to hollow metal doors, the core material in wood doors can be selected on the basis of performance and code criteria. The five common choices are open honeycomb fiberboard, solid mineral material, composite of block and stave, particle board, and even a rapidly renewable agrifiber.

Moving on to stile and rail doors, the basic construction results in an appearance that is quite different. Solid pieces of wood are formed and used as the basic frame of a door with the stiles running vertically and the top and bottom rails running horizontally. Inside of this basic frame, many options exist.

For example, very traditional raised wood panels can be incorporated using intermediate cross rails and a center stile all of which is treated with traditional wood working techniques to create familiar historical looking doors. The details of the panels can vary to suit different historical or traditional styles using common joinery, molding, or overlays as may be appropriately selected. It is usually important, however that all of the wood used is either the same species or a compatible species that expands and contracts at the same rate. Another design option is not to use wood panels between the stiles and rails, but lites of glazing of one type or another. This can produce a more contemporary appearance if desired while still blending with other wood elements of the space.

Whether flush or stile and rail wood doors are used, the final detail to address is the finish. Either an opaque or a transparent stain is common to enhance the natural qualities of the wood grain. Final clear coats are then specified in the appropriate gloss or sheen. All finishes can be applied either in the field or at the factory based on project needs or the degree of finish control required.

Laminated Doors

There are two types of laminated doors available.

Thermally fused, low-pressure laminate (LPL) doors: LPL doors are fundamentally constructed in a simpler manner than other doors but can be aesthetically very pleasing, cost effective and durable. Virtually hundreds of decorative and wood-grain LPL veneer options are available that are adhered to a dense industrial grade particle board core. Matching edge-banding is used on the top, bottom, and sides thus avoiding the otherwise typical black lines at laminate seams. This overall process has proven itself such that the faces won't chip, crack, or delaminate while providing extensive finish and appearance options. From a sound transmission standpoint, a 43 STC rating is possible. Fire-rated LPL doors have 20, 45, 60, or 90 minute ratings. Non rated doors are also available with a recycled core.

High-pressure laminate (HPL) doors: These doors are finished with a common plastic laminate with a decorative or wood grain pattern. As such they provide a consistent appearance from opening to opening in locations where consistency is important. There are literally hundreds of decorative colors and patterns to choose from and the durable surface provides easy maintenance. Like LPL doors, the solid core is available in different densities to achieve different properties. There is also some additional flexibility in the core material used including green properties of recycled, rapidly renewable, FSC certified, or no added urea formaldehyde core material. HPL doors have been fire rated at 20, 45, 60, or 90 minutes and also provide favorable sound control.

Regardless of the type of door and frame selected, the important thing to remember is that early decisions on these items will enhance the design process and contribute to an overall, integrated, and coordinated aesthetic.

Hardware That Puts Everything Together

Decorative hardware choices can add to the overall look and aesthetic of a space. Photo courtesy of ASSA ABLOY

Once the doors and frames are established in a design scheme, the next area of focus is the means to meet all of the functional operations of the door. That is accomplished through the appropriate and thoughtful selection and specification of hardware of various types. Again in this area, the choices are many such that the design aesthetic need not suffer but rather can be enhanced by the appropriate, deliberate selections made by the architect or designer.

Hanging Devices—Swing, Slide, or Hide

Once the doors and frames are selected, the design question is now how they are hung and how much hardware is needed or desired to be exposed. Typically, hinges in a variety of styles are used with varying degrees of visibility or intentional ornamentation. By contrast, door pivots can be used that are essentially concealed in the door and the floor at the bottom or at the head. They come in a variety of styles too such that the door can be made to pivot about its center or the pivot can be offset to push the door to a slightly different location when open. In some cases, if the door is meant to be self-opening as for handicapped accessible locations, an electrified, motorized system will be used. That can mean that the hinge itself needs to accommodate wiring.

The size and style of the hinge selected needs to accommodate the weight and height of the door while assuring that it will function properly over time. The common two knuckle hinge is appropriate for light duty doors as is a decorative “olive-knuckle” hinge. However doors that are located in higher traffic zones and are heavier in weight will be more readily served by three or five knuckle hinges. Taller doors will require more sets of hinges such that a standard light duty door that is 7 feet tall will do fine with 3 hinges (i.e. 1-½ pair) while taller doors will likely need 4 hinges (2 pair). The most durable of hinges is a continuous or “piano” style hinge that runs the full length of the door.