Sound Deadening and Sound Proofing the Van

We installed sound deadening material and noise-absorbing insulation into our van conversion. This was one of the very first tasks and honestly we did it mainly because others had done it, not because we noticed the van was noisy. However, once all these products were installed, we realized we don’t have to raise our voices now while driving, and really how much louder the driving experience was before sound deadening.

Our sound is managed by two products:

• Sound deadening, which dampens the van metal’s vibration
• Rockwool insulation,  which is an effective sound absorber

Very important time, money, and headache saver: only ~33% of the surface of the metal panel needs to be covered by sound deadening material. Tests show that further coverage does not significantly reduce vibrations.

Add in the Sound Deadening Roller installation tool

We used 2 boxes of sound deadening mat (total of 72 square feet) for our 148″ wheel base extended length high roof Ford Transit. We had a tiny bit left over.

Application is simple:

• Clean the surface with degreaser, as a clean surface is needed for the material to adhere.
• The material cuts easily with scissors, but leaves butyl gunk on the scissors so we used our old pair.
• Peel and stick it on! Some people use a roller to roll the material onto the van, but we had no issue just using our hands.

Optional: For extreme sound protection, a layer of Mass Loaded Vinyl (MLV) can be added on top of the sound deadening butyl material sound to block sounds. The main purposes, and downside, of this product is its weight. The heavier it is, the more sound it blocks – yet, the heavier it is, the worse it is for our van’s miles per gallon. We elected forego MLV and have no regrets, as the van is plenty quiet for us. Read more about MLV here.

Our insulation choice, Rockwool Comfortbatt, does double duty – thermal resistance for temperature as well as sound absorption. Rockwool was very easy to work with – it’s lightweight and cuts with a handsaw. Technically it can make you itchy if it touches skin, so when we started we put on gloves, long sleeves, and a dust mask. After a couple sessions with it we ditched that gear and there was no unreasonable skin irritation.

The insulation is made of stone wool, described as: “a natural material formed from volcanic diabase rock. The rocks are graded and crushed to a suitable size, mixed with coke and slags, then melted in a furnace at a temperature of 1500 °C. The melt is directed onto a series of rotating wheels where it is spun into wool. From the spinning machine the wool enters a chamber where small quantities of resin binder and mineral oil are added to lock the strands together and make them water repellent. ”

Rockwool has a sound transmission class (STC) of 45 in a standard residential. At that rating “loud speech is not audible” across rooms. That’s good enough for us! Per the Rockwool website, “Living close to an airport, the noise you hear inside your house is reduced by 40 percent if your roof is insulated with ROCKWOOL stone wool.”

Rockwool Comfortbatt has an R-Value of 4.3 per inch of thickness. We purchased the 3.5 inch thick product, hence a total R-Value of 15. This insulation is not sold at Home Depot, only Lowe’s.

Rockwool also makes a similar but different product, branded Rockwool Safe N Sound, which is available at Home Depot. Thickness is the difference between the two products, as the Safe N Sound is 3″ thick, but has the same amount of material and is therefore denser. This improves the sound absorption but decreases the amount of airgap and therefore Rockwool has stated Safe N Sound has a lower R-Value of 3.9. We prioritize thermal insulation over sound absorption, so we traveled to Lowe’s and bought Rockwool Comfortbatt.

Thinsulate is a great and popular insulation product for camper van conversions. It’s easy to install, not itchy, doesn’t off-gas, doesn’t retain moisture, etc. And importantly for this article, it is also an sound absorber.

Why didn’t we go with Thinsulate?

• Rockwool is also easy to install, doesn’t off-gas, and doesn’t retain moisture. It’s itchiness was insignificant in our experience
• Higher R-Value: 4.3/inch for Rockwool vs 3.3/inch for Thinsulate
• Rockwool is thicker: Thinsulate is sold in 1.75″ thickness, that means the installed product has total R-Value of 5.8. Since Rockwool is 3.5″ thickness, Rockwool’s total installed R-Value is 15, almost 3x higher than Thinsulate!
• Rockwool is cheaper! Rockwool cost is $0.80/sq ft and 3.5″ thickness, compared to Thinsulate’s approximately $2.38/sq ft and 1.75″ thickness.

Rest assured , if you go with Thinsulate, it is also a sound absorber! The best (and basically only) available online source for Thinsulate is Impact Products. Their prices on Amazon and eBay are usually the same, but more size options are available on the eBay listing.