47-55.1 Sound barriers / Interior insulation

[JDarby]

Wondering what are the good and not so good interior insulation options?

It seems like not a lot of area but when going threw the books it adds up pretty quick dollar wise so I am asking what ya'll can point me too?

The Classic Industries Catalog alone has many options that all look good.

As always Thanks in advance!

[nvrdone]

Check out water heater insulation at Home Depot or Lowes. Both are peel and stick so the floors etc must be clean of all debris. Then add a layer of jute rug padding with carpet on top. you should be cool and happy. Also, make sure you use the silver tape over all holes and all gaps. It wont be as quite as a new Lexus, but its better that bare floors with a rubber mat.

[joedoh]

I wrote this up a while ago and will repost it here.

Originally Posted by joedoh

remember that there are two sources of sound: direct and sympathetic. direct is air propagated, meaning the thing that creates the sound is within direct earshot and you hear it. sympathetic is based on resonance, meaning you hear something else vibrating sympathetically when it is directly hit by sound. if I sealed you in a steel drum, you could still hear me talking outside because my direct voice would strike the metal of the drum and vibrate, on the inside you would "hear" it even though there is no way the sound waves could penetrate the steel.

knowing that, seal the direct paths: holes in the firewall, floor, doors and door jambs, anywhere that air can leak in.

for the sympathetic paths, you can dampen their sound by lowering the "resonant frequency". big flat panels will resonate, and will do so more at the natural frequency of the panel, a frequency where the natural response is loudest with the least amount of sound. sound deadener works on this principle, adding mass (usually asphalt) to a panel lowers its frequency, and lower frequencies are much harder to reproduce and need a lot more power. ever bought a subwoofer amplifier? much more powerful, much larger. same idea.

adding mass has a finite limit though. once you lower the resonant frequency enough you can stop adding mass, adding additional mass makes things heavier but does not dampen the sound any more. so multiple layers are rarely needed, in fact complete panel coverage isnt really needed. I typically will dampen the flat and thin panels, like the firewall, floor, and trans tunnel, but resist complete coverage. over that but under the carpet I put a thick jute pad, which works on the principle of absorption of reflected sound (in a metal cab with a metal dash everything reflects!). so about a roll of foil backed asphalt roof sealer ($16 at home depot), a jute pad (~$60) and sealing the doors and glass gives me a quiet quiet cab.

[mr48chev]

I missed that the first time but well done Joedoe.

From what I have seen both heat and sound insulation have advanced greatly in the past few years.
Sound, it doesn't hurt to get over into the car audio groups and see what they say about various materials. They discuss not only materials but tricks to deal with those drumming panels that sometimes amplify outside sound or have their own sounds as air moves past them at speed.

I'm tired of heat and tired of outside noise that I don't want to hear with the windows rolled up and the AC or heater on. I don't need it as quiet as my BMW or Cad DTS were but outside of a bit of wind noise all I want to hear is my pipes when I want to and the sounds I have to hear.

I've been looking into Lizard skin but you have to buy separate products for heat and sound.

[fauXGT]

Trying to maintain the stock look on a heavily modified truck, I applied Lizard Skin on the entirety of the inside of the cab. Inside the dash, firewall, roof, floor, and inside the doors. applying extra on surfaces that I sanded flat. The product goes on like paper mache thru a straw, so lots of splatter. It greatly eliminates the oil can affect on all the surfaces. I thought it would be easier to apply in tight spaces compared to rolling out other products...and when sanded flat it looks like it's the stock surface. It is a bit of work, but I couldn't have achieved the look on all interior surfaces, including floors and kick panels. I've also installed the stock inside firewall insulated heat pad, just for extra. Still working on getting it on all 4s, but I honestly think that Lizard was worth the extra expense and work.

I do have to say that all of the products that I purchased for this truck project 3+ years ago has gone way up in cost. I'm glad I went insane when starting this endever and spent almost a small fortune then doing bulk orders on almost everything. Don't want to think of what it will cost in the next 3 years.
But don't listen to my lunatic rantings. It may lead to bankruptcy and divorce.

[62c30]

I've thought about using ATAC from DEI. It's supposed to be heat and sound deadening. It's a one coat for both and cheaper than lizard skin by the time you buy the heat and sound. Anyone used it before?

[e015475]

Here's what I did to address the points Russ made in his write-up

"knowing that, seal the direct paths: holes in the firewall, floor, doors and door jambs, anywhere that air can leak in."


Every panel that was removable, like the transmission cover and battery cover, I sealed with a gasket made from 3/16" closed cell foam. I used the Steele Rubber products on the doors and used the 'dollar bill' test to make sure there was contact everywhere. I run stock pedals so I found some rubber gators to replace the factory felt seals. For the steering column firewall penetration, I used Dumdum on the interior side and a boot on the firewall side to seal it. I found a Dodge shift boot and a substantial chrome trim ring that I mounted to the floor with nutserts so I could pull it down for a good seal.

..... adding mass (usually asphalt) to a panel lowers its frequency, and lower frequencies are much harder to reproduce and need a lot more power.

You can do it cheap with the foil-lined asphalt stuff from Home Depot, but it stinks (literally, especially in the Arizona heat). Killmat is about the cheapest alternative and that's what I used (Made in Russia - kinda strange) I had 100% coverage on the floor, underneath the seat, as far up the firewall as I could get it and the back of the cab, and on the roof. For the doors, I only covered about 40% of the door skin. As Russ mentions, complete coverage is probably overkill, but it came in 30SF boxes and I kept applying it till it was gone.

As Mr48Chevy suggested, I also looked at some of the car audio guy's suggestions, and I put a 1/4" layer of closed cell foam over all the interior surfaces I'd installed Killmat on.

The upholsterer who did the carpet put a nice jute pad, and that helps a lot. He even put jute and carpet under the seat. He also put carpet up the wall of the cab in back of the seat and carpet under the seat cushions, which probably helps a little with sound absorbtion in the cab.

All-and-all, I have about $100 in Killmat and foam, and maybe another $100 more in pedal gators, shift and steering column boots/bezels

Pic of the boots and bezels for sealing up the floor. (floormat is just a coconut door mat from HD that's been edge banded)



Killmat before the foam installation on the roof