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Hangar Door Deflection: Choosing the Right Roller Assembly
The amount of vertical deflection your building allows at the top of the hangar door opening directly affects which roller assembly is required. Using the wrong roller can result in doors that bind, come off the track, or fail to operate properly.
There are two roller options available for bottom rolling hangar doors:
- Fixed Rollers – for minimal deflection
- Telescoping Rollers – for buildings with greater structural movement
This guide explains what deflection is, why it matters, and how to select the correct roller type based on your building’s design.
What Is Deflection and Why It Matters
- Vertical deflection refers to the amount the building’s header or top guide rail may move upward or downward under structural loads (such as snow, wind, or live loads).
- Upward deflection can cause the door to lift off the bottom track.
- Downward deflection can cause the door to bind inside the guide system, making it unable to move left or right.
- Choosing the right roller assembly ensures the door operates smoothly, even if the structure flexes under load.
Roller Types & Deflection Limits
The correct roller type depends on the maximum vertical deflection your building allows at the door opening. Each roller type is designed to accommodate a different amount of movement.
- Fixed Rollers are designed for rigid structures with little to no movement. They are suitable when the vertical deflection at the top guide rail is 3 inches or less.
- Telescoping Rollers are designed for flexible or pre-engineered buildings. They can tolerate more than 3 inches of vertical deflection by allowing the roller to adjust with the movement.
Not sure how much deflection your building allows? We recommend confirming this with your structural engineer early in the design phase, as it directly impacts door design and cost.
Roller Type Comparison
| Roller Type | Recommended Use | Deflection Capacity | Cost Impact |
|---|---|---|---|
| Fixed Roller | Rigid structures with minimal vertical movement | ≤ 3 inches | Lower cost |
| Telescoping Roller | Pre-engineered or flexible buildings with greater deflection | > 3 inches | Higher cost due to articulation |
Fixed Roller
Fixed guide roller – no articulation
Telescoping Roller
Pivoting assembly absorbs vertical movement
Design Coordination Tip
Confirm the expected deflection at the door opening early in the project. This small piece of information will:
- Determine which roller type your door system requires
- Help avoid operational issues after installation
- Prevent change orders or redesigns later in the process
Consult your structural engineer to verify this deflection value, then share it with your hangar door supplier during design or bidding.
Final Notes
The roller system you choose must align with how your building will behave under load. A mismatch between the structure’s deflection and the roller system can lead to expensive, avoidable problems. When in doubt, ask us—we’re happy to review both options and help you make the right choice for your project.
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