If you live near a busy road and find it distracting, you’ve probably thought about how to block freeway noise. Depending on whether you’re trying to block freeway noise inside or outside, there are a few options:
- Add mass to walls
- Build window plugs
- Build a fence
- Plant some trees
- Install a water feature
In this article, I’ll look at why freeways are so noisy and irritating, and how best to block out this noise so you can enjoy a bit of peace and quiet at home.
Also read: How To Block Road Noise With Trees
Why Are Freeways So Loud?
It’s no secret that freeways are noisy, and living near one can be a nightmare. Cars make plenty of noise when they drive, and this is only made worse by driving at high speeds.
But what exactly is it that makes so much noise?
Other than sounds made by the car engines and horns and so on, driving on a road creates its own noise. In fact, the noise you’re trying to block is basically this.
The cause of driving noise is tires. Tires have tread to help them grip the road, but this also causes them to make lots of noise.
First, tire tread contains lots of gaps, generally in the form of grooves. As a car drives, air is trapped in these grooves and compressed against the road surface. The pressure builds, and the air is expelled, creating noise.
But then you also have the tires themselves making contact with the road. Tires are full of air and so are springy. This means that when they make contact with a surface, the tire vibrates and creates noise.
And because tires are essentially hollow, they’re great at resonating sound. For example, if you hit a wall with a solid object such as a wooden mallet, it makes less noise than if you hit the wall with a hollow object, such as a baseball bat.
So as you can see, there’s a lot to deal with when it comes to driving noise. It’s much worse on freeways because of the sheer volume of cars traveling on the road, combined with them all driving at high speed.
This freeway noise travels really far too. Typically, a freeway will register around 70dB at about 30ft.
Sound waves follow the inverse-square law, meaning they halve as distance doubles. A reduction of 6dB is approximately a 50% reduction in perceived sound, and this happens every time you double the distance.
For freeway noise to become almost indistinguishable from background noise (such as wind), you’ll need to be about 2.5 miles away from the freeway. This would drop the noise level to around 30dB.
So, arguably the best way to block freeway noise is to simply not be near it. But obviously, that’s not really possible, meaning you’ll have to use some soundproofing solutions.
Blocking Freeway Noise At Home
The first thing you need to consider before going any further is whether you want to block freeway noise indoors or outdoors.
It’ll be much quieter indoors anyway, as the building’s structure will absorb a large portion of the sound. Blocking freeway noise indoors is therefore much easier.
When it comes to blocking freeway noise outside, you’re slightly more limited in what you can do.
Because sound travels through air, the only way you’ll block it completely is by enclosing your outdoor space, meaning it’ll no longer be outdoors.
But by using some sound deflection and attenuation strategies, you can make a big difference to the perceived level of road noise you experience in your backyard.
This basically involves either reflecting the sound waves back at their source (deflection) or installing materials that’ll absorb some or all of the sound waves (attenuation).
I’ll cover some suggestions in more detail below.
How To Block Freeway Noise
Blocking sound indoors is much easier because you only need to add to the existing structure. You can simply add more mass to walls and then work on soundproofing windows.
Here are my top suggestions:
1. Add mass to walls
Adding mass to walls is pretty easy. You can either use drywall, which you can fix to the existing wall, or use mass loaded vinyl (see it on Amazon).
I’d recommend MLV as the better option because it’s specifically designed for soundproofing projects. It’s dense, flexible, and easy to work with.
You can staple or glue it to the existing walls and then seal any gaps with acoustic caulk.
As MLV is black and not the prettiest material, you might be best to cover it in another layer of drywall. You can then decorate this however you want.
2. Build window plugs
A soundproof window plug is basically a box you fit over a window to add more mass. Windows are a weak spot in soundproofing projects, and this is the easiest way to block sound coming through them.
For this project you’ll need:
- Medium density fiberboard
- Mass loaded vinyl
- Acoustic foam panels
- Saw, screwdriver, staple gun
- Measure the window, ensuring you have the correct height, width, and depth.
- Cut your MDF to size. You need 5 pieces: the 4 sides and a piece for the back.
- Cut your MLV and acoustic panels to the same size as the back piece of MDF.
- Assemble the wooden frame using screws, and fill any gaps with acoustic caulk.
- Stick a piece of MLV to the back and sides inside the plug.
- Then stick some acoustic foam panels on top.
- Finally, attach the handles to the backside and you’re done.
Your window plug should fit snugly into the window frame with minimal gaps. Gaps can let sound through, so the better the fit, the better its sound blocking properties.
The only real disadvantage of this option is that it’ll also block light from entering the room. For this reason, you might only want to use them at night.
Blocking Freeway Noise In Your Backyard
If you’re trying to block freeway noise in your backyard then you’ve got a slightly more complicated project ahead.
Remember you won’t completely block noise, but building a tall and solid barrier will do a good job of deflecting any noise pollution.
1. Build a fence
This might sound simple, but there’s a bit of research involved. First, you have to choose the right materials, and then you need to get the best height.
A brick or stone wall is perhaps the best suggestion because it’s thick and solid. But it also takes a while to build and is quite resource intense.
However, a brick or stone wall can reduce noise pollution by up to 50%.
Alternatively, you can buy acoustic fences. They generally use thicker and heavier materials than a standard fence, and so do a better job of deflecting sound.
Regardless of which option you choose, you’ll want to build it at least 15ft high. This might sound like a lot, but it’s the only real way to deflect airborne noise.
Either way, I’d avoid normal timber or metal fences because these won’t do a particularly good job.
2. Plant some trees
Planting a dense row of trees or shrubs is a more environmentally friendly alternative to building a new wall or fence.
Dense foliage has been found to reduce noise pollution by up to 50%.
I recommend using evergreen trees for year-round protection. The best choices include:
The disadvantage of using foliage to block noise is that it takes time for the plants to mature, meaning you won’t see results for up to 5 years, if not longer.
But trees can also help by providing their own noise. The sound of wind rustling their leaves sounds similar to freeway noise and will help to mask the irritating noise pollution.
Your best option would be to plant several rows of trees and shrubs in front of each other. You could also consider building a fence and then hiding it using shrubs; this would be pretty effective for blocking freeway noise.
3. Install a water feature
This option doesn’t help to block noise but will help to mask it. If the freeway noise is fairly distant, it should be enough to stop it from being a problem.
With this option, you’re essentially creating white noise that your brain can focus on instead of the sound of traffic. This isn’t the same as blocking it, but it should give good results.
I’d recommend either building a fountain or waterfall so that the water makes as much noise as possible. The more powerful the water stream, the better it’ll be for masking freeway noise.
Some Final Thoughts
Hopefully, this guide has given you some tips on how to block freeway noise. Blocking the noise indoors is much easier than blocking it outdoors, but you can still get some good results from the latter.
If you’re willing to get stuck in with a DIY project, it won’t be too difficult to build a sturdy fence that’s great at deflecting freeway noise away from your backyard.