Joining window combinations for large openings

A large opening is rarely one unit. How the units are joined, and where that joint is made, decides how the assembly performs and how long it takes to install.

Key facts

Window height up to 9 ft: 1 1/8" (28 mm) joint, base grade
Window height 9 to 11 ft: 1 1/8" (28 mm) joint, intermediate grade
Window height 11 to 13 ft: 1 1/8" (28 mm) joint, heavy grade

The joint is made in the shop, not on the scaffold

Multi-unit combinations are joined at the factory and delivered as one assembly. A joint made in a controlled shop is squarer and better sealed than one made at height in weather, and it removes the step where site-made combinations usually leak.

Depending on overall size and shipping method, an assembly may arrive fully joined or split into sections for transport and rejoined on site at a designed splice. Which of those applies is confirmed before quotation, because it changes the crane and access plan.

Three reinforcement grades, chosen by height

The joining mullion is 1 1/8" (28 mm) wide in every grade, so the sightline does not change as the structure gets heavier. What changes is the reinforcement inside it.

Window height up to 9 ft	1 1/8" (28 mm) joint, base grade
Window height 9 to 11 ft	1 1/8" (28 mm) joint, intermediate grade
Window height 11 to 13 ft	1 1/8" (28 mm) joint, heavy grade

What to send us

The opening dimensions, the intended split into lights, the floor-to-floor height, and how the units can reach the opening — through a doorway, up a stair, or by crane. That last one decides more than people expect.

The joining system is covered by a US patent held by the manufacturer.

FAQ

How wide is the joint between two window units?

The joining mullion is 1 1/8" (28 mm) wide, and it stays 1 1/8" in all three reinforcement grades. Only the internal reinforcement changes with height, so a taller, heavier combination does not get a fatter sightline.

Are large combinations assembled on site or in the factory?

In the factory wherever size and shipping allow, delivered as one assembly. Where an assembly is too large to ship whole it is split at a designed splice and rejoined on site. Which applies is confirmed before the quotation, because it changes access and crane requirements.

Source: Manufacturer’s published specifications for factory-joined combinations.

See this in a real project

Hospitality project, Irving — Irving, Texas
Hotel entrance, Gallup — Gallup, New Mexico

Send us the opening schedule and the project location and we will confirm in writing what applies to your case.

Request a quote →