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Frequently Asked Questions

Question: What choices do I have when selecting a door for my home or non-residential project?

Answer: That depends on where the door will be used, its function and, to no little degree, on design considerations.

Question: How many different styles of door can there be to choose from?

Answer: Doors come in a wide variety of styles, but there are a few basic types that will fulfill most needs. These include wood exterior entrance doors which are most frequently stile & rail doors, interior passage doors which are most frequently flush doors, French or casement doors, swinging or sliding patio doors, louver doors and screen doors.

Question: Just what is an exterior entrance door?

Answer: As the name implies, it is a door that allows entrance into a home or non-residential building. As such, the door must perform in a manner that allows ingress and egress, but keeps the outside elements from penetrating into the interior. The doors are commonly of stile & rail construction. This construction type is very sturdy and features heavy, exposed framing members, with inset panels of wood or glass. The vertical members are the "styles", and the horizontal members are the "rails". Sometimes flush doors are used for entry doors. Flush doors have a smooth surface with the core framing of the door covered by two or three layers of "ply" on either side that form the skin over the core and frame. The outermost ply is the veneer. If the door has two layers on each side of the core it is referred to as a 5-ply door. If it has three layers, it is a 7-ply (3 layers outside + core + 3 more layers = 7 ply).

Question: Since it has more layers, is a 7-ply door better than a 5-ply door?

Answer: There are two schools of thought on that. Some feel that more layers make a better door. Others point out that since the thickness of each ply is varied so that the total thickness of the "skin" remains the same for both the 5-ply and 7-ply door, there is no real difference in the amount of material provided. What really determines the quality of the door is the strength of framing and joining used, and the quality of the materials that make up the "skin".

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Question: How does a door keep the outside elements from penetrating into the interior?

Answer: Actually, the door works in concert with weatherstripping, the door frame, and the threshold to keep the elements at bay. Usually, the door itself has insulating value provided either by its mass, as in a solid door, or by insulating material fabricated into the core of the door by its manufacturer. The weatherstripping, doorframe and threshold prevent air penetration around the door.

Question: What else is unique about an exterior door that makes it different than a door used on the interior of a building?

Answer: An exterior door must also be finished so that it resists the elements. This requires either that the wood be sealed or that it be covered with a weather resistant material, such as vinyl, steel or aluminum. The exterior door must also be manufactured of materials that are weather resistant.

Question: Several types of doors were mentioned earlier. How many of those can be used as exterior doors?

Answer: Depending on design requirements, virtually all types can be employed as exterior doors. They also may be used as interior doors.

Question: Are the requirements for interior doors as stringent as those for exterior doors?

Answer: Construction requirements, in terms of ability to withstand such things as warping, twisting, cracking and physical damage, are fairly similar. The biggest difference is that interior doors do not have to be able to withstand the exterior elements. Obviously, the interior door can be constructed of materials that may not hold up well if exposed to dramatic changes in the weather, such as dry heat, rain, ice, extreme cold, etc. Exterior doors must be able to withstand these environmental extremes. Interior doors do not have to be weather-stripped, nor do they have to have the insulating value of an exterior door.

Question: What are the various parts of a door, and are they universal to all types?

Answer: Different types of doors have different components, but some nomenclature applies to virtually all types. A typical door contains a top and bottom rail as well as stiles. The top and bottom rail are the main horizontal structural members and the stiles are the vertical structural members. They also usually have a lock rail somewhere near the midpoint (unless they are solid, in which case no lock rail is needed). The lock rail allows the lockset (lock and knob or handle) to be installed in a solid portion of the door.

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Question: What is meant by a prehung door?

Answer: Prehung doors are installed in the frame before they are shipped to the building site or the lumber yard. They have significantly simplified the installation of a door. Prior to the era of prehung doors, a door was shipped without the frame or any hardware. This required a skilled installer to construct a frame, see that it was square and true, install hinges and then carefully fit the door to the frame so that it operated freely.

Question: How has the prehung door changed that?

Answer: Now a door comes already in its frame with hinges in place. It has been carefully mated to the frame, usually by a wholesaler or so-called jobber. At the site, only a rough opening is needed. The prehung door is installed in this rough opening—a process that requires far less time and work.

Question: What are the various parts of this frame?

Answer: At the top of the frame is a header, also sometimes referred to as a head frame. The side on which the lock fits is called the strike frame, and it is where the strike plate for the lock is installed. The side in which the hinges are set is, logically enough, the hinge frame. At the bottom is a sill and the threshold.

Question: What is a flush door?

Answer: A flush door is one whose face is flat and smooth.

Question: What is a panel door?

Answer: A panel door has several panels, interspersed with horizontal and/or vertical strips with the result being a three-dimensional appearance. A panel door is sometimes also referred to as a stile & rail door.

Question: What is a French door?

Answer: A French door consists of panes of glass separated by vertical and horizontal framing members. It opens and closes in the same fashion as other doors, swinging in a vertical plane.

Question: How are French doors used?

Answer: French doors are often used where the designer of a building wants to physically define spaces while still providing a view. This can occur either on the exterior, where access to the outside is desired without limiting the entry of daylight. Or it can happen on the interior of a house where one room may be separated from another physically but not visually.

Question: How are French doors different from patio doors?

Answer: Actually, many architects use French doors as patio doors. Patio doors are usually less elaborate in design. They may either be hinged and swing open, or they may slide from side to side on a track.

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Question: What are louver doors?

Answer: Louver doors consist of a series of slats, usually arranged horizontally and fastened between vertical structural pieces. They are frequently employed in situations where it is desirable to have air flow through the door, such as in closets or in laundry rooms.

Question: What are bifold doors?

Answer: Bifold doors consist of two or more panels. In addition to being hinged at one side, the panels themselves are hinged together. Such doors are usually employed when it is desirable to open a door into as small a space as possible.

Question: What is a pocket door?

Answer: A pocket door is a very specialized installation. The door actually slides into a cavity in the adjacent wall especially built to receive it. Pocket doors are employed when a swinging door would create an obstruction or when the designer wishes to create a flexible space between two or more rooms, thereby creating the illusion of a single room.

Question: What is the difference between hollow core and solid core doors?

Answer: A solid core door is, as the name implies, one in which the structural inner part of the door is solid. This inner core can be made of a variety of materials. These include a mineral-based material (used in fire-rated doors), particleboard, wood blocks or composition materials. A hollow core door denotes an assembly using strips or other units of material with intervening hollow cells. Whether hollow or solid core, all doors then have face panels on the exterior.

Question: From what material are these face panels constructed?

Answer: They can be wood veneer, composition materials, hardwood, plywood, high pressure laminates, or a combination of these materials.

Question: What are fire-rated doors?

Answer: Fire-rated wood doors are those that have been constructed in a manner to resist fire. They may be rated as 20 minute, 30 minute, 45 minute, 1 hour or 1 1/2 hour. To get these ratings, they must be tested and carry an identifying label from a qualified testing and inspection agency.

Question: What is the difference between an Architectural door and a Residential door?

Answer: Architectural doors are custom doors manufactured to meet specifications from an architect or door specifier for a specific project. These high quality doors are most commonly used in commercial applications, although Architectural doors are occasionally provided for custom designed homes. Architectural doors tend to be larger than Residential doors, and they are designed and constructed to withstand a high level of use. Residential doors are standard doors provided by the manufacturer for use in homes and townhouses. Although they are not designed and built for the level of use the Architectural doors are, there are many high quality residential doors available in the marketplace today. Several manufacturers have focused particularly on entry doors, and provide truly beautiful doors with sidelights as stock items that can be purchased and installed quickly and easily.

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