In order to keep the structure as light and visibly transparent as possible, door openings with a simple door header and sidelites are often preferred to framed and clad portal structure. The design of the doors themselves can play a role in which components to choose for the opening:

Frameless glass doors

Frameless doors provide the lightest aesthetic overall, and can usually be anchored with simple patch fittings that attach to the header and sidelites. They do come with some important considerations, however:

• They require a gap of approximately 3/16” on all sides, which can allow air, water and dust inside. Options are limited for door sweeps and weatherproofing with acceptable aesthetics. See more about how to address this issue in our post on all glass vestibule conditioning.
• A frameless door and portal offers limited options for automated openers, typically requiring floor mounted equipment, which is more vulnerable to dirt and water infiltration along with other environmental issues.

Framed glass doors provide much better options for weatherproofing, but of course they are not as light aesthetically.

The glass doors at the portal on the CD Adapco headquarters building use simple patch fittings attached to the header and sidelites for a light aesthetic.

Floating headers

A floating header, which spans the door opening and anchors to the sidlites, can work with both door types, while providing a lighter look than a fully framed opening, with room for openers and associated electronics.

A simple header tube was used at this portal within the entrance wall of St. Joseph’s Drexel Library. Wiring for electronic openers, and strike plates for panic handles could be hidden with the header, to keep the opening relatively light and clean looking. The glass lites above the door opening are supported by floor to ceiling glass fins, and not the door opening itself.

Portal structure

The key design consideration in determining whether or not a structural portal is needed, is whether or not the opening must be self-supporting. In other words, when the door opening must support the load of the materials above (wall/framing/roof), a structural portal of one type or another (steel, aluminum, stainless steel, etc.) is needed to prevent loads from above from compromising the operation of the doors. Sizing the appropriate structural members is based on the width of the door opening, the weight of the load being supported, and the locations of where loads are being transferred to.

The framed portal at the Wistar Institute provides a dramatic stainless clad opening. This type of framed structural portal can provide the best weather seal at the doors, while also supporting structural loads above.

Initial design strategy recommendations

All glass vestibules are more about designing a signature look at the entrance than anything. Therefore, Bellwether recommends that the design process begin with conceptual aesthetic requirements, and then followed by an analysis of space, access (door opening size, electronics, etc.) and weatherproofing considerations. Once critical aesthetic and access requirements are set, a structural analysis can be undertaken to determine the options that will place the fewest limitations on each.

The post Glass vestibule door openings and framed door portal design considerations appeared first on Bellwether Design Technologies.

Glass Vestibule Conditioning / Environmental Management

When properly executed, the vestibule’s design actively keeps outside elements from entering the building lobby. The double sets of doors keep heat loss and heat gain to a minimum, ultimately reducing the temperature swings that have to be made up by the HVAC system. The walk-off mats scrape sand, water and snow from visitor’s shoes to keep floors cleaner and safer.

During the design phase of a vestibule, we are often asked about the best ways to heat and cool them for comfort. This emphasis on glass vestibule conditioning (basically trying to create a mini lobby space) can be misplaced.

In terms of conditioning, think less about trying to mimic environmental conditions within the building, and more about designing a space that:

• Actively deflects its own heat gain / heat loss through low-e coatings, frits, tints, etc.
• Is pressurized properly to create an active curtain which keeps exterior elements in their place

Visitor Flow with a Vestibule

The size, configuration, and aesthetics of a jewel box vestibule serves to help visitors slow down and switch gears from the busy, unfiltered exterior world, to the quieter, and more orderly lobby space.

In terms of aesthetic design, we recommend an open and experimental approach. Make a strong design statement that sets the tone for the visitor experience within the building itself, and introduces the businesses that occupy it. An all glass vestibule is a excellent place to make that first architectural impression that occupants and visitors can sense tangibly. It is the first indication of the quality standards of the architecture and of the businesses within.

Again, the conditioning goal within a vestibule is to limit the intrusion of unwanted heat, cold, sand, water and snow, they keep the main building cleaner, safer, and more comfortable. And the primary design goal of an all-glass vestibule is to create a space that helps the visitor to experience the architectural intent, and transition from one mindset to another.

View our entire blog to learn more about Bellwether’s Design Development process, or visit our Glass Vestibule project page to learn more about Bellwether’s work with all glass vestibules.

The post All Glass Vestibule Conditioning and Design Considerations appeared first on Bellwether Design Technologies.

Vestibules are typically designed as an exterior feature that extends out from the face of the building, or as an interior structure that is flush with the face of the building, and a structure within the lobby. The first consideration is one of aesthetics, which has significant impacts on design and structure.

Aesthetics

The exterior vestibule provides the most dramatic impact at the entrance of the building. As shown below, the exterior vestibule becomes its own design feature and can make a big impact on an otherwise simple building exterior.

The interior vestibule can be virtually unseen from the street, and thus makes less of a visual impact from outside. The interior lobby view, however, can be quite dramatic.

1350 I Street, Washington DC – Exterior

.
1350 I Street, Washington DC – Interior

Glass Vestibule Design and Structural Considerations

A lobby wall structure with an interior vestibule is significantly easier to design, since the exterior wall handles the windload, rain and snow, (usually) without requiring these loads or conditions to be handled by the vestibule. In addition to the simpler structural design, the interior vestibule also does take additional space exterior space if lot lines or building envelope dimensions are a consideration.

The exterior vestibule must manage windloads, snowloads, rain, uplift, etc., like any other exterior structure. Different consideration must therefore be given to this structure and how it integrates with the building. Exterior vestibules contain a roof that acts as a skylight and canopy. This means that in addition to snowload considerations, a drainage plan or gutter system for rainfall must be integrated.

In the end, the choice of glass vestibule design will likely come down to exterior building aesthetics and space considerations. From there, the design approach will focus on the creation of an interior structure with typical deadload and deflection considerations, or an exterior structure with weather-related design considerations. For more inspiration for your next project please view our recent designs on our glass vestibule projects page.

The post Glass Vestibule Design Considerations: Interior Vs. Exterior Vestibule Design appeared first on Bellwether Design Technologies.