Many factors affect the proper installation and operation of doors. The most critical of these are edge clearances. Edge clearances are the distances between the door and frame at the head, the jambs, and between the leaves of a pair. When edge clearances are correct, doors and hardware function as designed.
Edge clearances are not only essential for the form, fit, and function of every door opening system — they are essential for life-safety. The National Fire Protection Agency (NFPA) specification NFPA 80-2007 requires that edge clearances be 1/8″ plus or minus 1/16″. These are the same edge clearances specified by the Hollow Metal Manufacturers Association (HMMA) for all openings, as documented in “Tolerances and Clearances for Commercial Hollow Metal Doors and Frames” (ANSI/HMMA 841-07).
Door and frame manufacturers design and build their product to meet these stringent tolerances. These same tight tolerances must carry over to installation. When installers follow the proper industry accepted practices, they can achieve these critical edge clearances. The most important thing a qualified installer can do is to follow proper installation practices, detailed in NAAMM HMMA 840-07, “Guide Specification for Installation and Storage of Hollow Metal Doors and Frames.”
When Clearances Are Wrong
When a door binds or even touches at the head, a jamb, or another door leaf, this is an edge clearance problem. Less severe, but also important, is when the clearances are not uniform around the door, creating an aesthetic problem and reflecting poorly on the workmanship of the whole job. In either case the installer must correct the installation errors to achieve correct edge clearances.
The first thing to check is that the frame is square, true, and plumb. This can be done with a series of measurements at the top, middle, and bottom of the frame, and by using a framing square or other tools specifically designed to check door openings.
If you can adjust the frame to fix the problem, then great. But what do you do if the frame is installed improperly and not easily fixed? Before tearing out a frame, think about using shims.
Using Shims to Correct Clearances
Shims are permitted by NFPA 80 as long as the shims are made of steel. Shims are typically 1/4″ × 4″ and come in varied metal thickness to suit the condition. Either hand-made or purchased, the shims should be made from corrosion resistant zinc coated steel so they can be used on exterior and interior openings.
The idea behind using shims is to change the position of the hinge relative to both the door and the frame. By being strategic, you can change the axis and position of the door swing relative to the hinge jamb of the frame. There are four shim positions to work with:
Shim A — Between the hinge reinforcement and hinge leaf on the frame side: moves both the door and the hinge barrel centerline in the negative X direction (toward the frame stop).
Shim B — Between the hinge leaf and door on the door side: moves the door only in the negative X direction.
Shim C — On the opposite face of the frame hinge reinforcement: moves both the door and hinge barrel centerline in the positive X direction (away from the frame stop).
Shim D — On the opposite face of the door hinge leaf: moves the door only in the positive X direction.
Fixing Common Conditions
Be aware that shims must be of equal size and correct thickness at each hinge location. If the shims are too thick, the door might suffer a condition known as “hinge bind.”
| Condition | Shim Solution |
|---|---|
| Gap too wide at lock edge | Place equal size shims in position C between each jamb hinge reinforcement and hinge leaf. Fine-tune with equal shims in position D behind each door hinge leaf. |
| Gap too narrow at lock edge | Place equal size shims in position A between each jamb hinge reinforcement and hinge leaf. Fine-tune with equal shims in position B behind each door hinge leaf. |
| Hinge or strike jamb toed out (out of square) | Place shims in position C and/or D at the bottom hinge. Fine-tune with a shim in position A at the top hinge. |
| Hinge or strike jamb toed in (out of square) | Place shim in position A at the bottom and possibly middle hinge. Fine-tune with thin shims in positions C and D at the top hinge. |
About the Author
David Taylor is the Sales and Product Development Manager at HMF Express and serves as Chairman of the Hollow Metal Manufacturers Association Technical Committee.