Three-Dimensional Adjustment Of Unitized Curtain Wall

In recent years, unitized curtain wall have gained increasing popularity, particularly in economically developed countries and regions. Compared to traditional frame-type curtain walls installed on-site, unitized curtain walls offer higher precision, greater efficiency, and reduced labor requirements at the construction site. The curtain wall units are assembled in factories, and on-site installation only involves mounting the panels.

While factory assembly of unitized curtain walls ensures high quality and efficiency, it also introduces new challenges. The curtain wall system must be installed on the actual on-site structure, which, as is well known, may not match the design drawings perfectly. Variations in height, depth, and left-to-right alignment are common, requiring the unitized curtain wall to have three-dimensional adjustment capabilities to accommodate structural discrepancies. So, how is this achieved?

1. Left to right

The connection between unitized curtain walls and the structure is primarily achieved through ground support brackets. The curtain wall units are hung on these brackets, which are in turn installed on the structure via embedded parts. Before concrete pouring, the embedded parts must be placed within the reinforcement cage, ensuring they become an integral part of the structure after concrete curing. However, during this process, the embedded parts inevitably deviate from their original positions—they may shift left or right relative to the design drawings. How can we mitigate the impact of these deviations?

To compensate for the lateral deviations caused by embedded part misalignment, embedded parts are typically designed as cast-in channel. These work in conjunction with T-bolts, allowing the bolts to slide left or right within the channel to absorb positional errors. Additionally, the curtain wall's ground support brackets permit lateral sliding of the curtain wall units. This dual adjustment mechanism ensures that even significant left-right deviations in the embedded parts can be effectively mitigated, maintaining the curtain wall's panel layout to meet design requirements.

2.Depth

Structural edge deviation is another common type of structural error. The edges of the structure may sometimes protrude or recede, whereas the position of the unitized curtain wall relative to the building is fixed—the distance from the curtain wall's finished surface to the axis must match the shop drawings. At the same time, the cast-in channel will also cause depth errors during installation .How can the curtain wall system compensate for structural edge deviations (depth errors)?

As previously mentioned, curtain wall units need to be mounted on ground support brackets. Since the position of the curtain wall's finished surface is fixed, the depth adjustment function must be achieved through these brackets. The cast-in channel and structural positions are already fixed, so longitudinal slots need to be created on the brackets to allow adjustment relative to the cast-in channel. After completing the adjustment, the brackets must be securely fixed to prevent any further sliding within the slots. Therefore, the brackets feature a tooth-like structure that interlocks with alum. washers for fixation.

3. Height

The most common height deviation in on-site structures is the flatness error. Very few structures can achieve the same level of flatness as shown in the shop drawings. To ensure the horizontal alignment of curtain wall panels, we use shim blocks (Silicone or aluminum alloy materials can be chosen) to level the ground support brackets. This adjustment is not only for aesthetic purposes but also for safety compliance‌.

After addressing the flatness issue, we must also tackle the problem of level height deviations. The horizontal height of each curtain wall unit is fixed and must match the design drawings, whereas the actual structural elevation on-site may have deviations of 1–2 cm. To mitigate the impact of structural discrepancies, the unitized curtain wall incorporates a height adjustment system in its mounting brackets. The curtain wall bracket adjustment system consists of two parts: the bracket fixed to the column and the hanger connected to the ground support code. These two components are then adjusted in height via the threaded holes on the bracket. Typically, this adjustment system allows for height adjustments of up to 25 mm, which is sufficient to accommodate on-site structural variations. 

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