Although thick and strong glass panels are used for high-rise buildings, sometimes a panel is damaged or even cracked due to extreme weather conditions or other factors. For example, a gust of wind could have picked up an object and blown it against a glass window. In that case, the glass panel needs to be replaced. In this article, we explain how glass panels are replaced and what options are available to do that.

The windows that are used and installed on high-rise buildings or skyscrapers aren’t standard glass windows, like used for regular homes. The main reason for this is that tall buildings are subject to great pressure, caused by the wind. Besides that, a glass skyscraper often has glass panels that function as walls and have to resist people or objects leaning against them.

Because of these factors, the glass panels that are used in high-rise building need to be very strong and have to be fabricated in such a way that they don’t shatter if they might be damaged. In general, two 6mm glass panes are used with a 12mm airspace between them.

You can imagine that a decent sized glass panel weighs quite a lot, so installing or replacing a window of a glass facade often requires heavy duty equipment. Sometimes, skyscrapers are even equipped with glass panels that span an entire floor and weigh even more.

Replacing glass panels

During the construction of a high-rise structure, cranes are used to lift the heavy glass panels to their position and workers stand on structural parts to guide and install the windows. But, after completion of the building, the cranes are removed and the replacement of large windows requires other measures.
Using a crane or mobile elevated working platform

The most obvious way to reach the area where a glass panel needs to be replaced is by using a crane from ground level and/or a mobile elevated working platform (MEWP).

A crane is able to lift heavy glass panels to the desired level so workers can install the window, possibly hanging suspended alongside the facade with a suspended scaffold or by using a MEWP.

This equipment will do the trick, but cranes on ground level do have their disadvantages: first, they need to be parked somewhere. High-rise buildings are often situated in crowded areas and to park a crane somewhere might only be possible when the street is (partly) blocked. Also, the costs of hiring heavy machinery are high, so when glass needs to be replaced from time to time, large expenses have to be made.

Another important factor is that cranes and MEWPs can only reach to a certain height, making it impossible to replace windows, more than a hundred meters high.

The Glass Replacement Unit

Our BMUs can be equipped with a Glass Replacement Unit (GRU) to be able to hoist and lower materials, but mainly it’s used for glass panels.

A GRU consists of a winch incorporated in the BMU with wire rope running from the base via pulleys to the end of the jib. A snap-hook is attached to the wire rope and is suspended in front (or at the back) of the gondola. The hook can carry various tools, including a special suction tool that can hold heavy glass panels.

Using a Building Maintenance Unit

The purpose of our building maintenance units (BMUs) is to provide access to the facade for all those who do maintenance work to the facade. In general, window cleaners will use the BMU to make sure that office workers, hotel guests or residents have a clear view and the structure looks impeccable from the outside. Especially when the facade is entirely made of glass, which is quite common in modern architecture.

Apart from cleaning a facade, BMUs can also be used for glass replacement on great heights without the use of other heavy equipment.

Elements of the GRU
  1. Winch / Hoist  unit with wire rope storage 
  2. Pulleys to guide the wire rope
  3. Anti-collision safety mechanism
  4. Snap-hook to attach equipment to

How does a Glass Replacement Unit work?

Replacing a glass panel of a common straight facade requires the following steps, after the suction cup is attached to the glass hook:

Step 1

The glass hook and the gondola move along the facade to the level where the broken glass panel needs to be replaced. Workers attach the suction tool to the broken panel and descend to ground level. Sometimes, the broken glass panel will be removed, taken inside the building and the gondola descends straight towards ground level.

Step 2

Once at ground or another lower level, the broken glass panel is detached and/or the new panel is attached to the suction tool. Workers always guide the glass panel, so the gondola and the GRU ascend simultaneously to the level where the glass panel needs to be installed.

Step 3

Workers inside the gondola, supported by workers inside the building, maneuver the glass panel into place and mount it to the window frame.

The added value of a GRU

Equipping a BMU with a GRU will facilitate easy glass replacement at any height and for any size of glass panel. Furthermore, it will reduce extra effort and costs that are needed when equipment needs to be rented or glass panels need to be transported throughout the building.

In our next blog, we will describe how additional tools for the GRU enables workers to replace glass windows in hard-to-reach areas of a facade, like inclining parts, protruding parts or other structural elements.