All You Need to Know About Curtain Walls

There are numerous types of walls bifurcated as per their functions and uses. Load Bearing Walls, Non – Load Bearing Walls are the major categories of walls. Additionally, Cavity walls, partition walls, etc. are common names that we majorly hear in our day-to-day lives. But have you come across the term ‘CURTAIN WALLS’?? This article will take you to the ride of the curtain wall system, its definition, its functions, its uses, and many such relatable aspects. 

We all are protected under a SHELTER – a shelter that comprises of a Foundation, Roofs, and Walls for protection. All the components in a building (i.e. Shelter) have their own purpose and structural considerations. Talking specifically about Walls, the definition and purpose of the walls are very simple to understand. The engineers have defined walls by uniquely adopting various standards. According to ‘R. Barry’ (Author of The Construction of Buildings), A wall is a vertical component that is thin and satisfies the purpose to divide rooms inside the building as internal walls and shelter from the exterior as an external wall. 

What are Curtain Walls?

Let us understand the technical definition of curtain walls. 

Curtain Wall can be defined as a non – load-bearing structure that acts as an exterior cover that provides durability and saves the inhabitant residing in it. 

Curtain Walls are lightweight external cladding that provides the envelope to the framed structure. Basically, these walls do not carry any structural load except their own weight and thus the core aim is to withstand wind and weather effects and protect the interior portion of the building. 

In the image above you can see the curtain wall application on a building. Next, you will understand about the different components of a curtain wall system.

Components of Curtain Wall and their Functions 

After understanding the actual meaning of the Curtain Walls, let us understand about essential components of curtain walls and their specific functions.

  1. Transom: It is a rail horizontally attached to the panel. Transoms are aluminium plates that are covered with some rubber and plastic materials. Transoms and Mullions form a grid structure. 
  2. Mullions: The vertical member contributing to complete the structural grid is called mullions. These mullions are screwed or joined to structure members with some of the anchors. Mullions fixed to the wall are covered with galvanized steel brackets to cover the irregularities visible on the wall. Mostly, Mullions are of timber, aluminium, and steel materials. 
  3. Vision Glass: Vision Glass is transparent glass installed in the space formed by a grid of mullions and transoms. Vision glass may be double glazed or triple glazed. Many times, spandrel glasses are used instead of vision. 
  4. Anchor: Anchors make it possible to join the mullions, transoms, and other such wall elements with structural members of the building. 

Next, you will understand about different types of curtain wall systems. 

Types of Curtain Wall System 

Generally, there three types of a curtain wall systems. Mostly, these types are classified based on the components used and their connections. 

  1. Stick Curtain Wall System
  2. Ladder Curtain Wall System
  3. Utilized Curtain Wall System

Now, it is time to have a brief look at the types of the curtain wall system.

1. Stick Curtain Wall System 

The name STICK is assigned because the walls are assembled between the floors in long pieces in stick form. Mainly, all the components are manufactured separately and then transported at the worksite where it is assembled and installed together. The Stick Curtain Wall consists of all the basic parts in such as glass, mullion, and spandrel. Amongst these, the mullions and transoms are subjected as sticks. 

Some of the advantages and disadvantages of stick curtain wall system are as follows: 

  • Connection and assembly of components are easier but require skilled labour. 
  • Enables to make complex, angular, and irregular 3d surface designs.
  • Fabrication of materials is easy compared to other systems. 
  • It is mostly suitable for small to medium-sized buildings as it is economical to prefabricate panels which are way costly in a unitised curtain wall system. 
  • The sequence and formation of designs can be changed easily. 
  • Sometimes, it increases the cost of installation due to the high demand for skilled workers.

Similar to Stick Wall System, we have Ladder Wall System which is a part of stick Curtain Walls. Let us have a brief look at it.

2. Ladder Curtain Wall System 

If we go through the ladder curtain wall system, then it is quite similar to the stick curtain wall system. In the ladder system, the mullions used can be separated or can be screwed together with the help of a half box and a plate by splitting it. Therefore, this provides flexibility to be cast at the manufacturing area which decreases the time at the working area. The major concern is that it reduces the ability to withstand structural deformation when compared with the stick system. On the flip side, the aesthetic appearance alleviates as the joints are visible where mullions are attached.

3. Unitised Curtain Wall System

Unitised curtain wall system – The name itself indicates its meaning.  It is precisely described by the ‘Madan Mehta’, ‘Walter Scarborough’ & ‘Diane Armpriest’ as (the author of Building Construction Principles, Materials, System), a unitised wall system where all the components of the wall are united at the factory and then brought to the construction site as a single unit. Apart from fabrications, glazing is also completed at the factoring site only. Once, the whole unit is reached at the site, it is erected at the required position with the help of the hoisting equipment’s and machines. Unlike the stick wall system, the whole unit is installed instead of installing the sticks of mullions and rails separately. This system is usually practiced for high-rise buildings and the height of the wall depends upon the floor height. 

Some of the advantages and disadvantages of curtain wall system are as follows:


  • Suitable for high-rise buildings up to many floors.
  • Eliminates the cost and requirement of scaffoldings and other exteriors support for site installation.
  • Enables installation from the interior portion too. 
  • It provides faster construction as on one hand facade is prepared in the factory and on the other hand concrete structure is constructed at the site. 
  • Better quality as all the parts are built and designed at factory so that necessary facades can be achieved.
  • Reduces the installation cost.
  • Provides better climatic and environmental protection.


  • Labour cost increases compared to stick system.
  • Transportation cost is comparatively high.

Next, you will learn about the materials that are used in curtain walls

Materials Used in Curtain Walls

So, after understanding the various systems of curtain walls, one must know about the definite materials suitable for the construction. This section will provide you a brief detail about the same. A small discussion about the materials is already covered above in the component section. But the information below will give you a complete idea.

There are several essential materials used in the construction of all types of curtain wall systems. 

1. Vision Glass

It is the transparent glass that can be double or single glazed glass which has less e-reflective coatings.

2. Spandrel Glass

It is glass that hides the structural members of the building such as columns, floors plumbing, electrical lines, and many more. Thus, it is opaque and known as non-vision glass.

3. Stone Veneer

Sometimes the glass panels are replaced by stone veneers. The stone veneers are cut into specific shapes and sizes which is slipped and placed in the aluminium frame.

4. Aluminium 

The panel frames in the curtain walls are made up of aluminium that provides the provision to fix the glass or stone or any other material in it.

Aluminium is not only used in curtain walls and panels but is also popular in windows. Do you want to know how? Just go through below article and relatable ideas.

Aluminium Windows: Its Types, Advantages & Disadvantages

5. Fibre-reinforced Plastics (FRP)

Basically, fibre-reinforced plastic is a combination of composite materials formed of polymer reinforced with fibres. Glass, carbon, aramid, or basalt are various fibres used in FRP.

To know more about how fibre reinforced glass works and whether it is beneficial to use it or not, refer link below.

Fibreglass: Uses | Properties | Advantages & Disadvantages

6. Louvers or Vents

Louvers are horizontal or vertical thin strips mainly used to provide air circulation and ventilation. Moreover, the louvers are installed in a space where ventilation or air is required to operate by the means of mechanical gadgets.

Advantages and Disadvantages

Now, you will learn about the advantages and disadvantages of curtain walls.

Nothing is flawless and ideal. Everything comes with some merits and demerits. So, let us focus on the favourable as well as unfavourable criteria.


1. Resistance to Weather Conditions

Curtain walls primarily provide strong durability against the effect of wind, sunlight and other climatic conditions. Additionally, these walls restrict the entry of air and water inside the building, because general structural members (i.e. Column, beam, floors, walls, and roofs); building has extra covering layer in the form of curtain wall.

2. Stability Against Sway

The most notable point is that curtain wall does not carry any load nor does it provide any structural stability.  But, as the curtain walls are often applied to multi storied buildings; they are impacted by high wind loads. Hence they are designed to reduce the sway.

3. Aesthetic Appearance

It is true to say that curtain wall is an old tradition. At the same time, it is absolutely right to say that the since last few years it is more accepted in general constructions. The curtain wall building stands differently because of its glazing effects and unique designs. Apart from tall buildings, curtain walls can be inserted in angular or asymmetric and non-uniforms structures also.

4. Thermal Insulation

The fire spreading speed decrease considerably between the floors as curtain wall acts as a hurdle and does not allow spread of fire easily from outer surface to inner region of the building effects and unique designs. While talking about thermal stability, curtain wall has tendency to reduce the temperature and save the inhabitants living inside the building. But this only works, if the glass and glazing used are treated and chosen wisely. Glazing protects the harmful UV rays and it does avoid direct contact to the people residing in the building.


  1. In comparison to the conventional buildings, the construction costs of the buildings with curtain walls are way high in expense. Furthermore, the maintenance cost of the curtain walls is high.
  2. Sometimes, the transportation of the materials and fabricated material does not prove economical if the distance between the construction site and fabrication site is more.
  3. Most advanced curtain wall types may require highly skilled labour, equipment and machinery.
  4. Installation of the curtain wall becomes tedious and work can be delayed in unfavourable weather conditions as most of the time these walls are installed from the outer side.
  5. Definitely, curtain walls support the sunlight emission and make the interior brighter but excessive brightness / glare is also not acceptable. In this case, indoor and /or outdoor shading is required to overcome the situation.

Uses of Curtain Walls

  1. Tall buildings are the major areas where the curtain wall system is commonly used. However, curtain walls are used at many other places too.
  2. Now-a-days, curtain wall in bridges is widely acceptable for better results. The bridge is one of the structures that mostly consists of curtain walls glazed with stone veneer or any other material as per requirement. Between the main supports, a thin curtain wall is placed and designed such that it does not carry imposed load.
  3. Besides this, Box Culvert is also a structure where a curtain wall is located below the box culvert. This type of wall in the culvert is also known as a thin wall. Also, to avoid damage in the walls, reinforcement is also added.
  4. In the canals, curtain walls are placed at both upstream and downstream sides to maintain stability. Flowing water has energy and for that canal falls are used to dissipate the energy. Canal falls have curtain walls at the toe and heel portion.
  5. Not only this, even in dams to protect foundation curtain walls are used which is known as Grout Curtain.


To sum up, it can be said that curtain wall system is the trending modern technique that provides a pleasant appearance, protection, and safety to building occupants. Curtain walls is a multipurpose structure that can be used at many places.

Image Courtesy : Image 6, Image 7

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