Door Basics

May 1, 2009

Locksmiths service door locks. If the door is equipped with a closer, be it surface mount or concealed, locksmiths service door closers. Locksmiths adjust door hinges so the door can close. Why not install doors? They can be a very profitable option without having to stock any product. If you are called out on a job and the door needs replacing, why not do the total opening? Grow your business. Don’t give the job away to another tradesman who may also install the door hardware.

The following is the first in a series of articles on doors. The series will cover how to measure and order the replacement door, door content, what is a stock door, installations, adjustments for closing, etc.

For this first article we will use a common door scenario. The door is located on the rear of a strip mall store. The flush (flat) door opens out. The door is hollow metal and is not fire rated. The bottom of the door has rusted.

The reason the door is in this condition is two-fold. First, the door is exposed to the elements, as there is no protection. Second, the top of the door has probably never been sealed. Water can run down the wall and the frame and enter the door through the top, causing the door to rust from the inside out.

Important: Be sure the top of the replacement door is sealed. This will extend the life of the door.

The out-swinging back door is hollow metal. It is equipped with three butt hinges. Locking is accomplished with a cylindrical lock and cylindrical deadbolt. The cylindrical deadbolt is used when the business is closed. There is a surface mount door closer with no evidence of through bolting. No evidence of through bolting indicates that the door is either manufactured of 12 or 14 gauge metal or the door will be probably be 16-18 gauge with a 14 gauge closer reinforcement plate welded into the door. More often than not if the door is 16 or 18 gauge, there is a closer reinforcement plate.

Note: Check the condition of the door closer. All door closers have a warranty. Many door closer have the production date stamped into the body. If the closer is not functioning properly or leaking, and the closer is still within the warranty period, you can contact the manufacturer for a replacement.

First, look at the door and the surrounding frame. Make sure the frame is in good condition and securely attached to the building. This could affect the operation of the door. Does the door swing smoothly, close and latch?

Never measure for a replacement door until the existing door operates smoothly. If the frame has settled or racked, dimensions of the replacement door must reflect the change.

Is there an even gap (clearance) around the door? The gap between the door and frame should be approximately 1/8”-3/16”. The door gap can change depending if the door has a bevel or square lock edge. Too large a gap on the lock edge of the door can result in the locks not being able to properly secure the opening. For exterior out swinging doors, a latch protector provides protection for the latch and bolt.

Is the door equipped with butt hinges or a continuous hinge? If the door is equipped with a continuous hinge, this information must be provided to the door manufacturer as it will affect the construction of the replacement door. If the door is equipped with butt hinges, continue with the next paragraph.

Open the door and check the hinges to make sure all of the screws are in place and are able to be tightened. Oversize Repair Screws having the same head size with one thread size larger are available from Major Manufacturing. This way these screws will thread into the hinge flush while having a larger diameter.

Check the condition of the butt hinges. If they are rusted, do not swing smoothly or stop at a specific place, they may need to be replaced. If the hinges are to be replaced, purchase ball bearing equipped hinges, which provide a smooth opening and closing operation.

Check the lock hardware to make sure it is in operating condition. If the lock hardware is in operating condition, it can be installed into the new door.

Use a plumb line to determine that the door and the frame are plumb (in vertical alignment). Take a carpenter’s square and determine if the frame is square. Also, measure the door diagonally from the top right corner to the bottom left corner and the top left corner to the bottom right corner. These two measurements should be the same or very close.

The next series of steps is to take measurements of the frame. (See Cross Section Door Frame Graphic, page 29.) Most door companies like the measurements in inches and fractions up to 1/32”. Always use a steel rule or steel tape measure when determining the dimensions. The more information provided when measuring the frame can help to insure getting the door having the correct dimensions.

We are using the illustrated sheet “Replacement Door to Fit Existing Frame. (page 27)” This guide indicates all of the measurements required for determining the dimensions of a replacement door. Follow the alphabetic order to determine the dimensions.

The measurements are taken from where the door is when closed. The width of the opening should be measured at the top (A), middle (B) and bottom (C). The reason why there are three measurements, this enables the replacement door manufacturer to determine the appropriate door size for a proper fit in the opening.

The next series of measurement are for the hinge locations. The hinge locations are measured from top of the frame header rabbet to top of hinge. The frame header rabbet is the flat surface adjacent to the soffit where the door enters when closed.

This door has three hinges. The first measurement is from the top of the uppermost hinge to the frame header rabbet (D). The second measurement is from the top of the middle hinge to the frame header rabbet (E). The third measurement is from the top of the bottom hinge to the frame header rabbet (F). These measurements vary amongst the door manufacturers and need to be the proper lengths for the replacement door to fit the opening.

The next measurement is from the frame header rabbet to the top of the strike plate(s) (G). Be sure to include the type of strike plate used i.e. “T” strike or ASA strike. If more than one strike plate is installed, such as a separate deadbolt and latch bolt for this door, you need to measure to the top of each of the strike plates and label each measurement.

The door height should be measured at the left and right sides of the opening. The measurements are from the frame header rabbet to the top of threshold, carpet or finished floor (H). If the dimensions vary include both measurements. If not include the measurement.

The size of the strike plate(s) must be measured (I). For this application, measure the deadbolt strike plate and the cylindrical lock strike plate.

The next step is to measure the hinge height (J). The three hinges should always be the same size. For this door, the butt hinge height will probably be 4-1/2”.

The hinge backset is the dimension from the soffit to the edge of the hinge leaf (K). This dimension is the same for all three hinges.

The frame rabbet size is the measurement from the stop, which is the edge of the soffit to the edge of the frame (L).

Butt hinges can have different leaf thickness. Measure the thickness of a hinge leaf (M). Standard butt hinge thickness for a 1-3/4” thick door is 0.134”.

If there is a threshold, measure the height of the threshold from the floor (N).

The next step is to determine the hand of the door (O).

Most commercial applications will be 1-3/4” thick door. However, always measure the door thickness (P). The door thickness is determined by measuring the distance between the front and rear faces. If a commercial exterior door is less than 1-3/4” thick, order the replacement door at 1-3/4” thick.

Determine if there is a bevel on the lock edge of the installed door. The bevel is the angle of the lock edge of the door. A door that does not have a bevel has a square edge. A beveled door is handed and requires a smaller gap than a square edge door.

The door is equipped with a surface mount closer, a cylindrical lock and a deadbolt. This metal door is probably equipped with reinforcement (an additional metal plate welded to the inside of the door face onto which the closer will be mounted). The replacement door can be equipped with reinforcement or the closer can be mounted using through bolting. On an exterior door, we would not recommend through bolting.

We now have the dimensions for the replacement hollow metal door. The next steps are to determine the door itself. This includes the gauge of the door skin. The average exterior hollow metal door skin is 16 to 18 gauge. We recommend using a 16 gauge skin to do the right thing. Doors can be ordered with 22 gauge to 12 gauge (smaller number is thicker).

Steel doors have an inner framework that may be made of wood, cardboard or steel. The door cavities are filled with a different materials depending upon the end-user’s application. There are steel doors whose cavities are filled for sound deadening, security, temperature, etc.

Door manufacturers will provide the preparation for locks, closers, exit devices, etc. Manufacturer and model information must be provided as well as height from the finished floor to ensure proper positioning.

Depending upon what is installed into or onto the door, reinforcement may need to be installed. This includes the locks, closer and any specialized hardware.

Look at the door. Are the seams visible? If they are visible, they appear as a narrow recess running along the top, bottom and edges of the door.

The more unique the door composition is, the longer the time may be required to construct and the more expensive the door.

Most door manufacturers offer stock doors in several categories. Vanilla doors are always in stock. They are built for standard framed openings. The doors themselves are slightly smaller (nominal) in order to fit the opening. They are 16-18 gauge with the manufacturer’s standard hinge placement. They can be beveled or have a squared lock edge. Slightly modified stock doors are available usually within a couple of days.

In addition, door manufacturers or their representatives can make small modification to the door. This includes adding in a deadbolt cutout or a cylinder turn, mortise cylinder opening or lever handle openings.

IMPORTANT: A door is standard depending upon the manufacturer’s determination of what is a standard door.

Custom doors can require additional time. Each door manufacturer has its own definition of what is a stock door and the time frame required for a custom door. In a future article, we will discuss stock and custom doors by manufacturers as well as outlets and shipping.

For more information contact the knowledgeable person at a locksmith distributor who sells doors or a door manufacturer who will refer you to a local supplier.

Rich Franken is sales and technical support rep for the Dugmore & Duncan Group in Corona, California. Rich has spent 25 years in the Door and Hardware industry primarily in the Southern California market.


Glossary of Terms

Closer Reinforcement Bracket: Reinforcement brackets used to provide additional strength for the attachment of a door closer.

Door Clearance (Gap): The space between the top of the door and header rabbet, the lock edge of the door and frame or bottom of the door and finished floor.

Door Handing: The term that designates the direction the door swings.

Double Acting: A door that can swing both ways. This requires the use of Double Acting Hinges.

Face: The exposed parts of the door when closed.

Floor Clearance: The clearance between bottom of the door and the finished floor. The opening is the under cut.

Flush Door: The faces of the door are a flat surface.

Gauge: The thickness of a hollow metal door face skin.

Gap: See Door Clearance.

Header: The horizontal member, forming the top of the door frame.

Hinge Edge of Door: The vertical edge of the door onto which the hinges are installed.

Hinge Jamb: Vertical member of frame prepared for installation of hinges.

Hinge Reinforcement: The reinforcement bracket mounted behind hinge preparation on jamb or door.

Jamb: Each of the two vertical members forming the sides of a door frame.

Manufacturer’s Standard Hinge Placement: Door manufacturers may use a unique measurement for placement of butt hinges. A door and frame can sometimes be identified by the hinge locations.

Mortise: Machining and reinforcing a preparation into door or frame for attachment of hardware.

Net Dimensions: The finished sizes of the door. For example, a 3070 Curries manufactured door is 35-13/16” x 83-1/4”.

Nominal Dimensions: The dimensions used to identify the door. For example, a 3070 door.

Opening Size: Size of frame opening measured between rabbets horizontally and between top rabbet and finished floor vertically.

Plumb: In vertical alignment.

Plumb Line: A string (line) that is attached to a weight to verify if an object, for our purposes a door or frame is in vertical alignment (plumb).

Rabbet: The offset formed in the frame to receive door. The rabbet is in front of the stop.

Sex Bolts: See Through Bolting.

Stop: Part of frame against which door closes.

Strike Jamb: The vertical member of frame prepared to accommodate the strike plate.

Strike Preparation: The portion of the frame modified to accept a strike plate.

Threshold: A raised surface positioned under the door when the door is closed and latched. A threshold can be manufactured of a variety of materials including metal, wood or stone.

Through Bolting: This method of installation uses Sex Bolts mounted onto the opposite face of the door. The object such as a door closer is mounted onto the other face of the door using bolts that thread through the door into the Sex Bolts.