Door Frames

Beyond the manufacture of the door panels, most manufacturers offer both pultruded fiberglass frames and Resin Transfer Molding (RTM) frames for their door systems. Pultruded fiberglass frames can be butt mounted or wrapped for most wall conditions, including insulated panel walls. RTM frames due to their solid profile can only be butt mounted. Frames are commonly available with a variety of mounting systems.

Pultruded fiberglass frames are typically constructed of ¼-inch-thick material. Fiberglass pultrusions were invented in the late 1940s and 1950s and are commonly in use in buildings of many types around the world. The AAMA describes the specific process as glass strands being pulled through resin baths and then shaped through a die or a mold to create a finished lineal material. The die is the key to the final shape and in this case will form the profile of the door frame. The lineal frame is then cut into sections for the head and jamb pieces and installed in the field.

By design, pultruded frames typically conform to Steel Door Institute and other industry standards for shape and installation methods. The corners of the fiberglass frames are usually mitered with no exposed fasteners, thus creating a desirable “clean” finish. Additional reinforcement can be added if required by the application or to accommodate specialty hardware. Most frames come standard with a satin finish in white, gray, tan, or brown. A variety of configurations and mounting options are also available, allowing products to be installed on concrete, brick, block, foam panel, drywall, and tilt-up wall systems.

Exterior door locations that are exposed to salt air or heavy moisture conditions are logical places to use fiberglass doors. Photos courtesy of Chase Doors

When selecting a door, frame, and hardware, be aware that in some cases a manufacturer may offer a “pre-hung” fiberglass door and frame package. In this case, the entire door system (including hardware) can be factory assembled and shipped ready for installation in the opening. Installation time of the door system can be reduced by as much as 70 percent in this manner. Note that double doors are typically pre-hung to ensure a proper fit and that hardware functions properly, then broken down for shipping purposes.

Design Considerations Using Fiberglass Doors

We have been making the point that it is important to match the right door material to the building application where the door is installed. It does not serve anyone well to have an inferior door in a demanding environment any more than it makes sense to have an over-designed door system in a moderate environment. Therefore, it is important to be clear during the design stage about the things that different doors may be exposed to, sometimes varying significantly in the same building.

Door Locations

In medium-duty rooms, building portions, or entire buildings, hollow metal doors may still be the most appropriate design choice. This might be true in general offices, warehouses, dry manufacturing facilities, general industrial buildings, restaurants, retail stores, and dry storage locations. It might also be necessary in locations that require more than a 1-½-hour fire rating since metal doors can be rated up to 3 hours.

In both interior and exterior applications where corrosion or damage is a concern, fiberglass doors are usually the more appropriate design choice. As we have seen, fiberglass doors do not break down or corrode the way steel doors do when exposed to water, corrosive materials, or heavy usage. Hence fiberglass doors are logically selected for virtually any building type with exterior doors that are exposed to high moisture or salt levels due to their location near salt water, process water, or particularly rainy locations.

Note that fiberglass door cores are typically electrically non-conductive and therefore eliminate galvanic corrosion, including concerns connected with coastal environments. They can also be appropriate for indoor water exposure in buildings such as car washes or facilities that require regular wash-downs.

Other building types by their nature are corrosive environments that place high demands on doors due to the processes carried out in those buildings. These can include chemical manufacturing plants, pharmaceutical manufacturing facilities, pulp and paper mills, and wastewater treatment plants. Other locations require diligence for compliance with federal regulations regarding health and cleanliness such as USDA and FDA Regulated Facilities including cGMP and GMP Regulated Facilities. Many fiberglass doors are suitable for use in these locations and in fact may be one of the only appropriate choices. The processes being performed in these locations might include food manufacturing and processing including fruit and meat processing.

Finally, fiberglass doors can be the appropriate choice in coastal environments, especially hurricane-prone regions. Fiberglass doors can be manufactured with considerable strength of the skins and core; therefore, can meet and exceed the stringent wind and large missile impact requirements of the Florida Building Code.

Beyond the location, some design options and considerations are rather universal. Obviously the needed door sizes need to be determined either for functional, code, or preferential reasons. Similarly, their operation needs to be determined as swinging, sliding, double acting, etc. In the event that fire ratings are needed, keep in mind that fiberglass doors can achieve up to a 90-minute rating.