If you’re in the trucking industry, then you know as well as anyone that sound dampening a transport truck is a classic problem. Trucking and also car companies spend a lot of time at figuring out the best ways to cut cost without compromising their products. In the end, though, soundproofing is not their top priority.
There are four primary sources of noise coming into a semi’s cab. The best way to soundproof a transport truck cab and sleeper is by introducing some high-quality sound deadening products in strategic locations.
Sound deadening is relevant because semi trucks produce a high degree of low-frequency noises (<90Hz) that can be difficult to absorb. Of course, I can’t give you an exact detailed fix on your particular truck, but I can certainly provide you with some basic rules to follow.
To keep your cost down, you should find out where the majority of the noise pollution comes from and begin from there. You can also buy an already made soundproofing kit for your transport truck, but I will dive more into that bellow.
Main Noise Causes in a Truck Cabin
1 – Noise Coming Through Hard Surfaces
Windows, floorboards, roof, doors, firewall. These are all outside noises that are transmitting into the semi’s cab through hard surfaces.
This noise is decreased by changing the mass/dampening proportion of the product you’re trying to soundproof. That is hefty carpeting, mats, rubber mounts, thick flexible seals to stop windows from transmitting.
There are a few easy fixes to solve this problem by concentrating on the thick heavy padding on the firewall and also the engine cover if cab over. You will need to cover as much bare metal as you can. There are some area where you might have to utilize thinner material to achieve this, but it will be well worth it if you succeed.
Use glue and caulking that is made explicitly for soundproofing projects because they are prepared to remain pliable and soft. This type of glue won’t crack over time. The best thing to use however is a sound absorbing mat that is self-adhesive. Most of the mats on the market today has this feature.
Do the same on the floorboards, though you might use a thinner lighter material than on the firewall. Once again, adhesive it down, or at least the pad to the carpet.
Velcro can also be useful. Likewise, you could get spray-on dampening (undercoat) and also utilize where it is most needed. However, many people don’t like using velcro because they want a more permanent fix to their noise problems.
Velcro could, however, be an excellent choice for someone that is only renting a truck for a certain amount of time and have to return it in the same state they started.
2 – Outside noise that enters via open spaces
You know as well as I do how wind noise can enter a car an cause enough noise to make for an uncomfortable ride. A transport truck is certainly no exception.
The sheer size of a semi truck will have many gaps and cracks to let wind noise in the cab. The gaps in the door and window seals. There is also clutch leaking in the floorboards to consider.
You will need to seal all these gaps with a soft and flexible seal, so you’re not providing a vibration path from one part to another.
The easy fix is of course to seal all the cracks and gaps. To do this, you will only need simple rubber grommets for the holes.
First, make sure the door and window seals are in great shape, so it does not let air squeeze through. You can use heavy tape to cover the small holes, cracks and other signs of wear that could cause wind noise while driving.
Don’t forget to check the seal around the windshield for any signs of wear. The signs of wear will be evident by showing cracks if the glass is not touching ONLY the seal or sealants around the windshield.
3 – Noise created inside the cab from parts hitting each other
If you’ve been driving thousands of miles in a semi, then you know what I’m talking about when I mention rattling. Especially rattles from objects hitting each other and hard surface to hard surface contact (loose panels, tools, etc…)
This is indeed one of the easiest fixes you can do to achieve a quieter ride unless you need to start tearing panels apart and such, but we’ll get into that in a bit.
First, of course, you’ll need to check every panel. Also, make sure the bolted items are secure and not moving around hitting another hard surface.
Don’t forget to take a look at all access panels.
Dash panels, in particular, are a frequent cause of rattle. The fuse panel and glove box door are usually the main culprits of rattling panels.
One person I was talking to in a Reddit forum told me that he uses silicone caulk to create a perfectly fitted seal around the rattling panel.
Put the silicone where you think the rattle is coming from, cover with plastic wrap and place the panel back on its proper position. After the silicone is dry, peel the plastic wrap off, and you should now have a perfect seel.
If you decide not to go with silicone caulk, you can also use little rubber pads. All trucks are different so make sure you find the problem before buying the proper materials, so you get the job done right the first time.
4 – Noise inside reflected by hard flat surfaces inside the cab.
Examples of inside noise reflected by hard surfaces will be coming from bare floorboards and even cabinet walls, especially if you have a back sleeper inside your transport truck.
All you would need to do is to cover any hard flat surfaces with something rough and flexible. Heavy thick cloth, carpet or leather (with a thin pad underneath it) would do the trick.
Products to Use to Soundproof a Transport Truck
After talking to many truckers that have actually done these types of projects, the product THEY recommend using would be Dynamat Self-Adhesive Sound Deadener Kit.
Another great product is the B-Quiet Extreme Composite Mat (Amazon). A lot of truckers use this product as much as the Dynamat, so the choice is yours. Sometimes it just comes to pricing, but either product will work wonders in semi sound deadening projects.
If at all possible apply a noise insulation mat that is at least 3/8″ thick. The one that offers you the most weight and thickness per dollar.
The best thing about the Dynamat sound deadner kit is that it is almost 1/2″ thick so this will be plenty of thickness to reduce a high amount of noise and vibration.
How to Install a Sound Deadener Mat
The surface of the semi truck you are applying sound deadener mat to should be clean of dust, moisture, grease and other foreign materials.
Measure and cut off a piece of Dynamat or B-Quiet sound deadening mat using scissors or a utility knife. You should not cut the pieces too small since it will only take longer to apply.
Keeping the pieces around a square foot will speed the process considerably. Heating these types of sound deadening mats (with a heat gun or hair-dryer) before applying is not required as is the case with many other deadeners made from different materials.
As long as it is applied at or above room temperature, it will form a solid bond to the metal in which it’s implemented on.
Peel the paper backing off (if it is a self-adhesive mat), and slowly lay the material down inch by inch. Take your time and slowly push the material into the contours of the panels.
Remember to mark off any clip holes and screw holes that will be covered, so you can cut them out as soon as a sheet has been applied.
Some mats come with a rough side and a smooth side. The rough side of the mat should face the cab, and the smooth side has to make contact with the panel you want for sound deadening.
This is very important and might be considered common sense, but not everyone would know this fact.
Other materials you can use are carpeting. The thicker, softer and heavier carpets will do a better job in sound insulation versus different types of carpets.
You can find tape, rubber seals, grommets, silicone sealant (caulk) at your local hardware store or by clicking this Amazon link for all the smaller sound deading materials.
What I would not recommend is using roofing tar on a transport truck in hopes of sound deadening and soundproofing. Wait until you have the money to buy what you need to do the job right.
Trust me, sloshing roofing tar on the inside of a semi cab that is worth well over a hundred thousand dollars is probably not the best idea.
Soundproofing and sound deadening a transport truck will make all the difference in the world in the quality of your ride. You spend a lot of time in a long haul truck, and it should be at least quiet enough to hear yourself think.
By reducing the decibels, you will be able to listen to the radio at a much lower volume which will be better for your health. This is something people only realize after the fact and have no regrets in going through this process.
Let us know at Soundproofguide if you have any suggestions for soundproofing your semi that we might have overlooked. I read a lot of what truckers had to say in forums and were very careful to only chose the right advice to relay to you.