Spacers

Insulating GlassSpacer

An insulating glass spacer is placed within the unit to separate the two or more plies of glass. Viracon’s offering of insulating glass spacers are available in black and feature a variety of thicknesses. When specifying an insulating glass unit, it is necessary to specify the material and thickness.

Warm Edge Spacer Simply Superior

Viracon Thermal Spacer (VTS®) is a proprietary formulation consisting of black thermoplastic with integrated desiccant and primary seal that is chemically bonded directly to the glass and secondary sealant. VTS replaces the traditional spacer, desiccant and primary sealant with a single, better-performing component available in a variety of thicknesses and sizes up to 130” x 236”. Argon fill is included, and a secondary sealant is applied. VTS carries a special 12 year insulating warranty.

SpacersExplore.

Design Considerations

Spacer options to match your design criteria

	Stainless Steel	VTS®
Nominal Thickness	Black	Black
5/16″ (7.5mm)	Yes	Yes
3/8″ (9mm)	Yes	Yes
7/16″ (11mm)	Yes	Yes
15/32″ (12mm)	Yes	Yes
1/2” (13.2mm)	Yes	Yes
9/16″ (14mm)	Yes	Yes
5/8″ (15.5mm)	Yes	Yes
23/32″ (18mm)	Yes	Yes
3/4” (18.5mm)	Yes
7/8″ (22mm)	Yes
1″ (25.4mm)	Yes

Warm Edge

Spacer materials that improve the U-Value beyond the performance offered by aluminum are commonly grouped together under the category of warm edge spacers or warm edge technology.

Viracon’s recommended spacer is VTS®. Black stainless steel spacers are available. Contact your Viracon representative for more details.

Thickness

The thickness of the spacer determines the distance between two glass plies in an insulating unit. Viracon’s typical 1” insulating units are constructed using a 1/2” (13.2mm) nominal thickness spacer. However, a wide variety of alternate thickness spacers are available.

Even a minimal change in the thickness of the spacer can affect solar performance so it is important to carefully consider and include the thickness in a specification.

Note

Stainless Steel and VTS® can be used in spandrel applications.

Viracon offers pressure adjusted insulating units suitable for elevation changes between manufacturing location and installation site, if required.

Black painted and black anodized finishes are interchangeable.

Spacer Performance

Improve U-Value performance

Spacer Thickness

The thickness of the spacer will determine the distance, or space, between the two glass plies in an insulating unit. Viracon’s typical 1” insulating units are constructed using a 1/2” (13.2mm) nominal thickness spacer; however, a wide variety of alternate thickness spacers are available.

Even a minimal change in the thickness of the spacer can affect solar performance so it is important to include the thickness in a specification.

7/8" VE1-48 Insulating

1/4" (6mm) clear with VE-48 #2

15/32" (12mm) airspace

1/4" (6mm) clear

VLT:: 47%
Winter U-Value:: 0.31
Summer U-Value:: 0.30
SHGC:: 0.38

1" VE1-48 Insulating

1/4" (6mm) clear with VE-48 #2

1/2" (13.2mm) airspace

1/4" (6mm) clear

VLT:: 47%
Winter U-Value:: 0.31
Summer U-Value:: 0.29
SHGC:: 0.38

1-1/16" VE1-48 Insulating

1/4" (6mm) clear with VE-48 #2

9/16" (14mm) airspace

1/4" (6mm) clear

VLT:: 47%
Winter U-Value:: 0.31
Summer U-Value:: 0.28
SHGC:: 0.38

Selecting Spacer Material

When selecting a spacer material, it is necessary to be aware of the different U-Values used in the glass industry.

Center-of-glass (COG) U-Values represent the center of the glass. Center-of-glass values provide an effective way to directly compare glass products without bias from spacer material, framing or unit size.
Edge-of-glass (EOG) values represent the perimeter of the glass unit affected by the spacer material.
The framing the glass unit is installed into also has a separate value.

These values are weighted based on the area of the unit to provide an overall U-Factor. The overall value is typically an input needed to run whole building energy calculations and determine code compliance.

Performance

		Aluminum Spacer 1/2" (13.2mm)	Stainless Steel Spacer 1/2" (13.2mm)	VTS® Spacer 1/2" (13.2mm)
1" Low-E Insulating	Center of Glass U-Value¹	Rough Opening U-Value²
Conventionally Glazed Framing System	0.25	.391	.379	.371
Conventionally Glazed Framing System	0.25	CR³ 48	CR³ 52	CR³ 55
2-Sided Structurally Glazed Framing	0.25	.354	.334	.319
2-Sided Structurally Glazed Framing	0.25	CR³ 53	CR³ 57	CR³ 60
4-Sided Structurally Glazed Framing System	0.25	.336	.312	.293
4-Sided Structurally Glazed Framing System	0.25	CR³ 56	CR³ 60	CR³ 66

Sealant

Primary and secondary seal properties

Sealant

PIB is the primary seal of the insulating glass unit, preventing moisture vapor transmission into the unit’s sealed space. The silicone secondary seal acts as the adhesive that holds the unit together in both conventional and structurally glazed systems. Both the PIB and structural silicone must maintain adhesion to the glass and spacer throughout the life of the unit.

Silicone is uniquely resistant to ultraviolet light and is the only sealant capable of being exposed long-term to UV, temperature extremes, and harsh atmospheric conditions. The high strength of silicone makes it ideal for structurally glazed applications.

Sightline

The sightline is the edge dimension of the insulating glass unit covered by the spacer. Insulating glass in a conventionally glazed system typically utilizes a 1/2″ sightline.

The sightline for insulating glass in structurally glazed applications must be calculated based on the unit size and wind load. This ensures there is enough silicone to glass contact to appropriately support the insulating unit and exterior glass ply when the glass is under load. Sightlines are calculated based on ASTM C1249 Standard Guide for Secondary Seal for Sealed Insulating Glass Units for Structural Sealant Glazing Applications. Viracon offers a Deflection and Sightline Reference Guide to assist in identifying the appropriate sightline based on glass size and load. Contact Viracon for sightline requirements specific to your project.