Air leaks bring down the energy efficiency of a building. Here is a look at the main causes of air leakage in residential and commercial buildings. We also cover some possible solutions.
Air leakage happens when outside air enters and exits a building in an uncontrolled way. The main culprit is openings and cracks in the building roof and walls.
When air exits a building through cracks in this way, we call it exfiltration. Infiltration is the opposite, the flow of atmospheric air into a building.
It’s immediately obvious that there is a lot of difference between air leaks and ventilation. Ventilation refers to fresh air that moves in and out of a building by design. This decreases stuffiness and unpleasant odours, and it also helps control the amount of moisture in a building.
But it’s not a good idea to rely on air leaks to provide the same benefits. In fact, air leakage can lead to excess moisture, which leads to mould and other health risks. It also has a host of other downsides, and living in such buildings is both dangerous and expensive.
Generally speaking, builders strive to cut down on air leaks as much as possible. They also provide controlled ventilation. This article looks into some of the reasons why air leakage is undesirable. Then, we cover the main causes and some prevention methods.
Consequences of Air Leaks
Chief of all is the negative impact on energy efficiency.
Air leaks are a major energy sink. During the winter months, it becomes far more difficult to heat a building to the desired temperature.
When cold air and wind enter a building through the cracks, it affects the temperature. This makes it unpleasant for the inhabitants. It can make the winter months noticeably uncomfortable.
But even more importantly, this issue increases heating costs. In the case of buildings that use by fossil fuels for heating, it leads to excess CO2 emissions that can have a major impact on the environment.
You already know that energy-efficient buildings are a growing trend in Australia. Constructing airtight buildings is a good way to keep up with the times. It can also be a prerequisite for certain types of certification. For example, it can help a building reach a Green Star rating, which is awarded by the Green Building Council of Australia.
And then there’s the question of moisture control. Air leaks lead to moisture accumulating on walls. This causes mould to form and it can also accelerate rot.
There are other health concerns to consider as well. Infiltration allows pollutants to enter your home at an increased rate. This includes microbes and spores, which may grow especially quickly in a damp environment. But allergens such as pollen can cause problems as well.
All things considered, airtight buildings are safer and more comfortable to live in. They are also far more energy-efficient, which increases their value in many ways.
The Most Common Causes
It’s clear that it’s in every homeowner’s best interest to make buildings as airtight as possible. They can easily repair many types of leaks. But there are situations where the fixes would need a builder’s expertise.
In either case, the first step is to identify the cause. There are many different ways for uncontrolled air to get into a building.
Here’s an overview of some frequent causes of infiltration and exfiltration.
Depending on the structure of the building, there could be leak-prone areas that require special care. Let’s look at some construction choices that lead to a higher likelihood of draughts.
Lack of Drywall
Buildings that have dropped ceilings and angled staircase ceilings are less airtight. This is because these areas often lack an additional layer of plaster or drywall. The same is true for knee walls – short, upper-level walls that fit to the slope of a roof. In some buildings, the areas behind skirting boards may lack proper insulation too.
These are problems for builders to deal with. However, homeowners do have some effective solutions at their disposal.
It’s important to block the airflow in the attic so that it doesn’t spread to the entire building. A good way to do that is to fill up plastic bags with unfaced fibreglass insulation. Placing reflective foil over the problem areas works too.
Basements and In-House Garages
When a building has a basement, it is naturally more prone to air leaks. In these cases, the cold air comes directly from the foundation. Many older houses need extensive modifications in the basement area. But caulking the gaps is an excellent stopgap measure. Garage doors can be subject to weatherstripping as well.
This form of lighting is a common source of air leakage. Each light needs to be insulated separately, which can be time-consuming. In the case of new homes, the owners might be advised to opt for a different way to position lights.
Here is another factor that can seriously impact the rate of air leakage.
On the windward face of the building, wind creates a higher pressure zone. This leads to infiltration on that side. The non-windward walls are subject to lower pressure instead. This is where most of the exfiltration happens.
In both cases, the best option is to seal the gaps and cracks on the surface of the walls. Let’s look at some examples of how to do that.
Doors and Windows
The most significant leaks are noticeable around doors and windows. Residents will experience draughts and drops in temperature in these parts of the house.
Homeowners themselves can combat these air leaks by weatherstripping every door. Note that this includes attic doors as well. Weatherstripping works with insufficiently sealed windows. In the case of windows that don’t open, caulking can be an appropriate solution as well.
But these simple measures aren’t always enough. For old buildings, the doors and windows often need a full reconstruction. In this case, the solution can be to install new and better doors and windows. While this can be a major building work, the benefits are significant.
In the case of new buildings, it’s important to select high-quality windows and doors that seal well.
Pipes and Kitchen Units
Air leaks are common around sink pipes and soil pipes. Additionally, they can happen through:
- the panel beside the tub
- behind kitchen counters
- behind appliances
In short, leaks can be a problem anywhere where there is pipe penetration.
Sometimes, these gaps are an error in construction. But they can also be created later, in the case of plumbing repairs.
This problem has a fairly straightforward solution. If the gaps are smaller than 1/4 inches across, it’s enough to caulk them. For homeowners, it’s usually best to use acrylic latex caulk. This is easy to apply even if you have little experience with household repairs.
In the case of larger gaps (up to 3 inches), soft foam is necessary. This is another affordable and easy-to-use tool.
Electric Cables and Fittings
Much like plumbers, electricians can leave gaps through the drywall. This is another problem that people can solve by caulking and it doesn’t usually need expert help. The first step is to find all the draughts around electric fittings and other installations.
The way warm air moves through the building creates stack effect. As the lighter warm air flows up a building and through the roof, it is replaced by the heavier cold air. This puts pressure on the upper levels of the building and the attic.
Once again, dropped ceilings tend to cause problems and need proper insulation. Properly sealed windows are a must-have. We already mentioned that sealing the attic door is crucial too.
We briefly mentioned the importance of good ventilation. However, it’s important to keep in mind that ventilation pipes create an opportunity for air leaks to develop. The same is true for dryer vents.
But chimneys are another important entry point for cold outside air.
Chimneys and Flues
According to building regulations, builders must leave a 1-inch space between metal flues and the wood framing around them. In the case of chimneys, this space needs to be 2 inches wide.
Clearly, this leads to air leakage. But fortunately, there are simple ways to cover up these gaps without compromising safety.
Aluminium flashing can be used for this purpose. Once it is cut to size, you can slot it into place using silicone caulk. Then, you form an aluminium cylinder around the flue pipe and cut along the top and the bottom edge.
Homes with a fireplace need a fire-safe seal as well. In this case, it might be better for homeowners to seek professional advice.
The Final Word
As energy-efficient buildings become the norm, it’s now even more important to make buildings airtight.
Air leaks can cause a great deal of damage to a building’s integrity, and they are costly as well. Finding ways to fix this problem should be a priority for homeowners and builders alike. Some repairs are simple but others require major changes.
Installing new doors and windows is one of the most effective ways to combat air leaks. For instance, louvre windows can help make your building more energy-efficient. They are a good choice for builders looking to earn Green Stars and create a pleasant, safe interior space.
If you’re interested in the other benefits of louvre windows, contact one of Safetyline Jalousie’s Business Managers now.
Building Air Tightness and Façade Leakage Testing – CETEC
Green Building Council Australia
Air Leakage Basics – The Energy Conservatory