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Return Air Ducts In Wall Cavity – What Are They Used For?

If you’ve been tampering with your walls for home improvement reasons, then there’s a chance that you may have run into gaps between two layers of a wall. If you’re a first-time renovator, it can come as a shock to you.

Return Air Ducts In Wall Cavity

What you have found here is a wall cavity, and they’re a standard feature of many building regulatory systems 

If you’ve never come across this in your renovations, you’re going to have quite a few questions about this subject. What exactly are these wall cavities for in your home? What benefits do they have? Are there any drawbacks?

We’ll be discussing all these aspects and more, as we not only go into deeper details about wall cavities but also the solutions too!

Wall cavities are necessary for keeping good airflow throughout a structure. But sometimes trapped debris and water can stop these from doing their job.

Return air ducts help keep good airflow through wall cavities for much longer, preventing structural issues in the long run. 

What Are Wall Cavities Used For?

So, what exactly are wall cavities there for?

Well, generally speaking, wall cavities allow for air currents to flow through and around the structure of a house. These airways are sometimes known as supply or return-air pathways.

They connect the pathways in the wall with outside air and other open spaces in a home.

They do this, without compromising the integrity of a building. With a strong concrete foundation, and the frames and ties still connecting the two walls (sometimes known as outer and inner leaves).

These structures still function as single-walled objects.

Pros Of Wall Cavities

There are plenty of great reasons why many homes will use wall cavities in some way. One of the biggest is that they are often much better for insulating your home.

The air that gets trapped between the two parts of the wall provides a buffer for transmitting heat from the inside of the home to out and vice versa. , more than a single-layered house!

The same even goes for sound too, so noises inside the house are better contained.

Plus, this is a cheaper option for builders to use than making a single-layered brick wall to achieve all these same features. So, it’s better for a budget, too!

Issues With Wall Cavities

But, despite their pros, there is a serious restriction on how many wall cavities can be in a building’s design, and with good reason.

Because wall cavities are not airtight, differing pressures from inside and outside the house will change. This brings in air from the outside, and plenty of elements with it.

These can range from trace amounts of pollutants that can enter a wall cavity’s airways, to even mold particles.

The humid temperatures inside wall cavities can be a haven for bacterial and mold growth. These can circulate in your home and can bring their issues in large enough quantities.

All this available airspace provides plenty of room for a fire to spread into the structure of a house, too. Should one break out, at least.

Now, this isn’t to say that wall cavities are fire hazards on their own (brick walls do not make for good fuel for the fire).

But those clear air pathways provide plenty of oxygen for the fire to spread. Especially with enough heat in-between layers of the wall.

And, as we’ve already explained, that warmer air is bound to gather in these nice open empty spaces!

This is why you will rarely see wall cavities used throughout the entire building they are in.

What Are Return Air Ducts?

Return Air Ducts In Wall Cavity

Return air ducts will be put into these wall cavities to solve these problems.

So, what exactly are they?

What Return Air Ducts Do

These air ducts that you add into wall cavities help do what wall cavities do, but more. In these duct cases, they connect to a furnace or air conditioner that you install with the system.

This installation allows for ventilation that is not only more direct but is often cleaner too.

It’s worth noting that because builders put them into wall cavities, return air ducts are designed and built into the wall at the same time that the cavities are.

Benefits Of Return Air Ducts

This more directed circulation improves the benefits that wall cavities already have.

Plus, you’ll also avoid a lot of the issues that wall cavities often have. The airflow in a return air duct filters much better.

This means that you’re less likely to get any more hazardous particulate. The same goes for the vent of fire too!

Pretty cool, right?

Plus, there is way less of a chance for mold to grow and spread in the duct than in a wall cavity. Even if it did, the affected area will be much smaller, and much more manageable to treat.

Issues With Return Air Ducts

The first issue that becomes clear to many people is the increase in budget that they’re going to need. Not for the ducts themselves, but for the air conditioners that they often must attach to.

You can also find that dirt and dust can build up inside the vent every few years. Cleaning this can be a difficult job to undertake without professional help.

Final Notes – Are Return Ducts Necessary To Cavity Walls?

So, on the whole, how exactly do about returning ducts? Are they necessary if you’re planning on having a wall cavity in one of your building’s walls.

You don’t need to have a return air duct installed into a wall cavity, especially if you’re only using them a little during construction. In these cases, there is not enough room to install them, and the benefits are not worth the extra costs.

But if you are planning on having a larger section of wall with these open spaces, a return air duct will do your home plenty of good.

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