What Is A Building Envelope & Why Is It Important?


During the construction of a house or building, the term building envelope may be used a lot. Particularly during the early stages.

But what exactly is a building envelope and why is it so important? And what role does it play in the building of a house?

If you’re starting out on your own building project, whether you plan to do any of the work yourself or not, it pays to know as much as possible about the process.

In this guide, we are going to take a look at the definition of a building envelope and the key reasons this is so important during the construction of a building.

What is the building envelope?

In its simplest form, a building envelope is the exterior (sometimes referred to as the shell) of a building. It acts as a boundary between the interior and exterior.

However, that is not all it does. It is a well-thought-out engineering system that must maintain and protect the structure and everything within. This includes moisture control, temperature control, structural integrity and air pressure boundaries.

This encompasses all the key components of the structure, including the roof, walls, windows, doors and floors. And these all play an integral role in getting the structure and building envelope just right.

What types of materials are used for building envelopes?

There is no one size fits all approach when it comes to building envelopes. This is because the materials used will vary depending on the climate, environment, design and other regional variants. The correct material will need to be selected carefully to create the best internal conditions.

That being said, there are several types of materials that are most commonly used for building envelopes. These include:

  • Asphalt
  • Composite
  • Wood
  • Metal
  • Clay
  • Slate
  • Rubber
  • Brick
  • Stone
  • Concrete
  • Vinyl
  • Aluminium
  • Fibreglass

Why is the building envelope so important?

Of course, with the building envelope making up a huge part of the structure, it might seem obvious why it is so important. That being said, as we briefly covered in the definition of a building envelope, it is so much more than just a structure. It must also fulfil many other important criteria and we’re going to look at these in more detail below.

1. Ventilation and air control

One of the key functions of a building envelope is to allow for proper ventilation whilst also protecting the structure from too much air leakage. This is because strong winds can increase the amount of air getting through the envelope if it’s not sealed properly.

So getting the balance just right means treading a fine line. But doing so is a sign of quality craftsmanship. This ventilation versus wind resistance of the building envelope is also important for energy efficiency.

2. Insulation can be attached to the building envelope

By adding thermal insulation to the building envelope, you can make the building more energy-efficient and therefore more cost-effective. This is because the insulation reduces the amount of energy required to heat and cool the building. Therefore, the envelope is vital for making the building more efficient.

3. It’s also important for fenestration

Fenestration is the arrangement of windows in a building and in this case it can also include doors.

The placement of windows and doors throughout the building envelope is very important. This is because maximising sunlight, as well as ensuring well-sealed doors and windows is vital for a good design and comfortable building.

It also helps to make the building more functional, generate heat and regulate the temperature and airflow. Therefore, building the envelope and ensuring the perfect placement of windows and doors is critical.

Get this wrong and you risk your building being drafty, cold, damp or dark.

4. The building envelope is critical for moisture control

Finally, closely related to airflow and water resistance is moisture control. This is another important element of the building envelope as it helps to regulate the transfer of moisture both in and out of the building.

Moisture can present a number of risks to the overall structure and integrity of a building, therefore, the envelope must be constructed with this in mind at all times. Every component must be addressed to prevent unwanted moisture, particularly in humid or damp climates as these can be especially demanding.