Avoiding Conflicts in Designing Stile and Rail Wood Doors
While many of today's stile and rail wood doors project a rich, highly-crafted image and provide many years of reliable service, they can spell trouble if individual components are incompatible with one another. This may require a heightened sense of vigilance on the part of specifiers unfamiliar with the details of door construction and design.
With stile and rail door manufacturers now capable of matching a variety of custom architectural designs, it is quite likely that contemporary, historical, or even 90-minute fire-rated stile and rail doors will become the focal point of a building's permanent collection of fine furniture.
Yet if stile and rail doors are to be fully functional, the selection of appropriate door components cannot take a back seat to design considerations. For example, doors with overlay moldings may require a lock rail or wider stiles to ensure compatibility with the hardware. Some hardware, such as slimline push bar exit devices, mounts close to the face of the door and requires a flat surface to operate properly.
All hardware that complies with the requirements of the Americans With Disabilities Act (ADA) utilizes a lever for the retraction of the latch. If overlay moulding is positioned too close to the lever, it will not have the clearance required to operate smoothly.
We sometimes see situations where the body and cover of the door closer hang down below the top rail and partially cover the raised or flat panel. This can create mounting problems for doors with a narrow top rail, while being aesthetically unpleasant. How can you avoid this potential dilemma? Simply make the top rail about 6" wide, thereby allowing the entire closer mechanism to be installed on the flat part of the top rail instead of hanging down over the panel.
What if an opening calls for a two-lite door? This requires the lock rail to be adjusted upward, or the exit device to be relocated downward, so that the device is centered on the lock rail. Also, with this type of door, there is always the potential for someone's hand to slip off the top of the exit device and penetrate the glass, resulting in an injury. It is important to note that traditional wire glass does not meet the ANSI Z97.1 or the CPSC 16 CFR 1201 standard for safety glass. The risk of serious injury can be significantly reduced if the glass type complies with the safety glass standards.
There are other traps to avoid when designing door layouts. For example, is the stile width adequate to house the latching hardware? Most hardware for architectural doors require at least a 5-inch wide stile. To be on the safe side, it's prudent to go with a 6-inch stile along with a 6-inch top rail. To avoid still other potential conflicts, it is also advisable to:
Design for mortise pockets that are generally 4 ½-inches deep.
Use lock backsets that are 2 ¾-inch on center.
Retain some dowels at the lock rail.
Specify bottom rails that are wide enough to meet ADA requirements and accept a kick plate.
Install viewers (if used) at a point where the door is at least 1 3/8-inches thick. Moreover, fully mortised door bottoms cannot be used in conjunction with a concealed vertical rod fire exit device or a mortised flush bolt. Nor should concealed closer bodies be used in stile and rail doors. Also, it is advisable to limit the use of a concealed closer or overhead stop arms in fire-rated doors.
Due, in part, to cost factors, stile and rail doors are seldom manufactured using a single, exotic type of wood. Unlike wood veneer flush doors, stile and rail doors require several thicknesses of veneer and lumber. Possible choices include PS White Maple for the stiles and rails, and Quarter Figured Anigre or Birdseye Maple for the panel faces. Panel face veneer is usually very thin -- 1-36" to 1/42," and can readily be obtained in a majority of the exotic species.
Another important consideration in specifying a stile and rail, or even a wood flush door, is the core material's "memory." In this instance, the term is used to describe a core material's ability to return to its original shape when a fastener, namely a "threaded-to-the-head" wood screw, is removed. Wood-based stile and rail cores have the best memory, while non-combustible (blocking) cores have no memory at all. Initially, both combustible and non-combustible cores (none mineral core) have more than adequate screw-holding power. But if a fastener is withdrawn, it must be replaced with a longer and larger diameter fastener -- one in the non-combustible blocking-type core -- to maintain an acceptable level of screw-holding power. Consider including a statement in your specification that reads as follows:
"If non-through bolted fasteners are to be used in fire door cores, and they are removed for any reason, the replacement must be ½" (13mm) longer along with the next size larger root diameter fastener."
Conflicts also should be avoided when specifying fire doors. True stile and rail fire doors are available from several manufacturers in all ratings through 90 minutes. A conflict can occur if the specifier doesn't realize that the 90-minute stile and rail door is 2-1/4" thick. It is imperative that the frame and hardware accommodate a 2-1/4"- thick door.
A careful review of some of these common conflicts should ensure smooth sailing the next time you have a project requiring the use of architectural stile and rail doors. Let your imagination drive your plans, but keep an eye out for those potential pitfalls.
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David San Paolo is Technical Director for The Maiman Company, an architectural door manufacturer located in Springfield, MO (www.maiman.com).
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