Specialty FabricationOffset
Specialty FabricationOffset.
Offset, or step-glazed units, describes having the edge of one glass ply extend beyond the edge of the other glass ply on one or more sides. Offset units are defined by the number of offset edges and which ply is offset.
Viracon can provide offset insulating units with 1, 2 or 3 edges offset. For the offset, the exterior ply must be larger than the interior ply. This is referred to as an exterior offset.
Viracon does not fabricate staggered insulating units where both glass plies are the same size and assembled so they are offset from one another.
Offset Guidelines
Designs incorporating offset insulating units can be complex so the following items must be considered.
Quotes
To ensure the offset units can be manufactured by Viracon for a given application, all requests must be reviewed and approved prior to receiving a quote.Offset Distance
The standard offset distance is less than or equal to 3/4” (19 mm). Offsets greater than 3” are not available. Offsets >3/4" up to 3" are provided with no warranty.Heat Treatment
All glass plies must be heat strengthened (HS) or fully tempered (FT) in an offset insulating unit. It is recommended that all fully tempered glass also be heat soaked.Edge Deletion
The deletion will be continuous from the offset glass edge to the spacer with 95% of the coating removed.Sightline
An increased sightline may be required for offset insulating units due to shear load on secondary sealant from the outboard glass ply dead load. Viracon will calculate the sightline for all offsets.
Silicone Fill Options
The secondary seal in Viracon’s insulating units is silicone. There are three fill options available for offset insulating units.
Normal Fill
The silicone edge may vary and have a rounded appearance at the corners.
Buttered Fill
A silicone layer is applied to the surface of the offset lite.
90° Fill
A custom fill where the offset lite is masked to achieve a uniform silicone edge. All requests for 90° fill offsets must be reviewed and approved prior to receiving a quote.