Choosing the right hangar door system is essential for ensuring operational efficiency, structural integrity, and lifecycle performance. Among the most common types are bottom rolling hangar doors and sliding hangar doors, each suited for different building conditions and aircraft access requirements. This guide breaks down their core differences, advantages, and considerations to help project managers, architects, and aviation engineers make informed decisions.
What Is a Bottom Rolling Hangar Door?
A bottom rolling hangar door is a mechanically supported door system where one or more door panels roll along a floor-mounted rail or track system. These panels may operate independently or in a connected configuration, enabling large clear spans without imposing structural loads on the building’s roof system.
The primary movement mechanism involves steel rollers or sealed ball-bearing carriers placed under each panel, guided laterally by top stabilizing rails. Common configurations include:
- Uni-directional: All panels stack to one side.
- Bi-parting: Panels split at the center and move to opposite sides.
- Floating group system: Panels can operate in tandem or independently, offering pocketless stacking options.
Bottom rolling systems are especially useful for aircraft maintenance, repair, and overhaul (MRO) hangars, commercial aviation terminals, and defense aviation facilities, where opening widths often exceed 200 feet. Due to the floor-based load distribution, they minimize stress on vertical supports and eliminate the need for heavy roof reinforcement.
What Is a Sliding Hangar Door?
A sliding hangar door is a type of horizontal movement door that shifts along a guide path, either via bottom rails or top-hung tracks, depending on the design. The term “sliding” is broadly applied and may include top-supported systems, slab sliding doors, and telescoping multi-leaf panels.
Sliding systems are often used in smaller hangars, FBO (Fixed Base Operator) facilities, and retrofit projects where existing structures cannot accommodate large-scale load transfers to the ground. These doors can feature:
- Manual or motorized operation
- Sealed weatherstrips to protect from elements
- Nested pocket configurations for space optimization
The key advantage is their simplicity and reduced floor preparation, making them cost-effective for projects with limited structural rework. However, because some sliding designs are top-supported, they require adequate roof truss capacity to bear panel weight and wind loads.
Key Differences Between Bottom Rolling and Sliding Hangar Doors
Choosing between bottom rolling hangar doors and sliding hangar doors requires understanding their distinct mechanical behaviors and structural requirements.
| Feature | Bottom Rolling Doors | Sliding Doors |
| Structural Load | Transferred to foundation | May load roof or floor |
| Track Location | Floor-mounted | Floor or ceiling |
| Panel Operation | Independent or grouped | Often fixed-track slide |
| Clear Opening | Full-span opening possible | May require pocket |
| Weather Resistance | Excellent with bottom seals | Variable, depends on build |
| Maintenance | Moderate (track cleaning needed) | Low to moderate |
| Ideal Use Case | Large-span hangars | Light aircraft, small hangars |
Bottom rolling doors offer greater scalability and customizability. They’re favored where structural flexibility, clear wide openings, and modular panel motion are critical. On the other hand, sliding doors excel in cost-sensitive, space-constrained, or light-duty hangar projects where simplicity and ease of integration take precedence.
Pros and Cons of Bottom Rolling vs Sliding Hangar Doors
Bottom Rolling Hangar Doors
Pros
- Load Transfer to Foundation: Ideal for structures with limited roof capacity.
- Modular Panel Control: Allows independent or floating panel configurations.
- Full Opening Access: Unobstructed spans, beneficial for large aircraft.
- Customizable Configurations: Can be bi-parting, uni-directional, or pocketless.
Cons
- Floor Rail Maintenance: Requires frequent track cleaning and debris removal.
- Installation Complexity: Needs precise rail alignment and concrete thresholds.
- Higher Initial Cost: More materials and engineering involved.
Sliding Hangar Doors
Pros
- Simpler Installation: Especially where top-supported designs are possible.
- Lower Upfront Cost: Less structural preparation required.
- Compact Operation: Efficient for small or mid-size hangars.
- Suitable for Retrofit: Easier to implement on existing buildings.
Cons
- Limited Structural Flexibility: Often not suitable for very wide openings.
- Roof Load Concerns: Top-supported panels demand high truss capacity.
- Panel Stacking Limitations: Fixed stacking may reduce clear width.
When to choose bottom rolling doors
- MRO and Military Hangars: Where door openings exceed 150–200 feet.
- New Construction Projects: That support in-ground rail installation.
- Wind-Prone Locations: Where roof-mounted systems may be compromised.
- Facilities Needing Panel Modularity: Enabling partial or sectional opening.
When to opt for sliding doors
- General Aviation and FBO Hangars: With moderate aircraft sizes.
- Budget-Conscious Builds: Where simplicity and low structural impact are priorities.
- Retrofit Applications: Where modifying foundations or walls is limited.
- Hangars with Adequate Roof Capacity: For supporting top-hung tracks.
Conclusion
Bottom rolling hangar doors provide unmatched flexibility for large-span, high-use aviation structures. Their ability to transfer loads to the foundation, enable multiple panel configurations, and withstand harsh conditions makes them ideal for MRO hangars, military aircraft shelters, and commercial aviation terminals.
Sliding hangar doors, by contrast, offer cost-effective simplicity. They’re preferred in FBO installations, general aviation buildings, and retrofit projects where roof capacity is sufficient and wide-open spans are not essential.
For projects prioritizing maximum opening width, wind resistance, and panel customization, bottom rolling doors are the superior choice. For projects emphasizing low cost, ease of integration, and structural simplicity, sliding doors are more suitable.
FAQs
Bottom rolling doors use ground-supported rails and rollers, whereas sliding doors may use ceiling or floor tracks to move panels horizontally. The key distinction is load transfer — to the foundation in bottom rolling, and to the structure in many sliding types.
Bottom rolling doors are better suited for large span hangars, offering greater panel control and structural flexibility without overloading the roof.
Yes. Both bottom rolling and sliding hangar doors can be motorized. Bottom rolling systems commonly use floor-mounted drive units, while sliding doors may use ceiling-mounted motor rails.
Bottom rolling doors are typically more durable for heavy-duty applications, especially when engineered with weather-sealed rails, steel panels, and industrial-grade carriers.
Bottom rolling doors require routine track maintenance to prevent debris-related jams. Sliding doors, particularly top-hung, generally have fewer floor-level maintenance needs but may require hardware inspection at ceiling level.
