Asphalt Sound Deadener replacement

[39LaSalleDriver]

Thought I'd wing this past folks. While disassembling my interior (39 Lasalle) to redo the wiring,  dash, and carpet I found what I am sure was the original underlayment of a sort of fiberboard impregnated with asphalt? on the floor pans and such, over which was a layer of jute.

In studying up on such things,  I see most commonly recommended modern foil backed products to reinstall. Has anyone thought about or used asphalt impregnated house sheathing commonly found at home improvement stores as a replacement?  Looks pretty much like the same material to me. It has the same feel, look, density, and thickness as the original stuff.

[Bobby B]

Jon,
Hi. First of all, it's not the same from your big box store. Second, why would you want to use an asphalt based product when there's so much better out there. Do it once, do it right. Here's the best product for your money, without going for the "Name" brand. The asphalt stuff is being phased out. Good Luck!
                                                                                                                                                                Bobby

https://www.ebay.com/itm/Noico-80-mil-36-sqft-Car-Sound-Deadening-Mat-Sound-Deadener-Insulation-Material/261751448064?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

[chrisntam]

I used dynamat and dynaliner in my car.  Expensive, but it's done and done right.  Carpet was a bit of a challenge to install due to the 1/2" thickness of the dynaliner.  Mines a convertible, can't really tell if it did any good or not, the thin top & top down makes for lots of road noise ( when on the highway next to other vehicles.

[fishnjim]

I've used roofing tar, both filled and unfilled, and other tars in the past when it's all that was available to me.   What you have to worry about is temperature stability and bleed through.   Some of the old floor "boards" got hot and these can melt/bleed.   Not the best choice of materials these days.   Plus tar doesn't allow moisture to "breath" so you can make situation worse by trapping moisture against steel.   It's much preferable on the exterior than interior, and avoid if possible.
As far as what I would recommend, would be to take it back to sound metal, repair if needed, then coat with epoxy paint/primer, then apply any coverings.   It's a trade off of originality vs making it last.   

[39LaSalleDriver]

Jon,
Hi. First of all, it's not the same from your big box store. Second, why would you want to use an asphalt based product when there's so much better out there. Do it once, do it right. Here's the best product for your money, without going for the "Name" brand. The asphalt stuff is being phased out. Good Luck!
                                                                                                                                                                Bobby

https://www.ebay.com/itm/Noico-80-mil-36-sqft-Car-Sound-Deadening-Mat-Sound-Deadener-Insulation-Material/261751448064?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

To begin with, I didn't say I "WAS" going to use this material. At this point it is a semi-rhetorical question, though despite all the cautions noted here, I haven't necessarily ruled it out. I am seeking first hand experience of someone who may have contemplated such a thing themselves. I can't imagine I'm the first one to come up with the similarities.

You state that it's "not the same from your big box store." What specifically is different about it? The material I pulled out of the car is a dense, pressed card/fiber board type material, about 1/2" thick, impregnated with asphalt, and breaks/falls apart if bent too much.

The material I was casually looking at in my local Home Depot is a dense, pressed card/fiber board type material, about 1/2" thick, impregnated with asphalt, and breaks/falls apart if bent too much. Not saying you are wrong, but specifically how is it not the same?

As for there being better products out there, I have no doubts about that. By the same token, there are better cars out there that I could be driving than a 1939 LaSalle too! Trust me, I have done some serious investigating on modern alternatives. If one really wants to dig into it, there are folks far more knowledgeable than me who will school you extensively with hard science about how the commonly accepted practice of using duct insulation, or cheap Ebay alternatives is borderline useless in comparison to more expensive products made specifically for cars.   

Yes, I know "nobody will ever see it," but in many ways, I'm one of "those guys" who prefers to redo things to original specs if I'm going to have to redo them anyway. At least, after I weigh the pros and cons of doing such.

Despite all it's failings, something about using a product that is chemically, compositionally, functionally, and structurally identical to what was in the car originally from the factory appeals to me a bit more than a foil backed modern (albeit superior) product. Just wondering if this material is it. If not, I would likely do what everyone else has done and go with the product like you listed.

For the record, my floor pans aren't really that bad. I'm going to be hitting the worst spots with a wire brush, and then coating them with Corroseal where appropriate. Then priming and painting the whole shebang.

[Bobby B]

You must be referring to Ice & Water shield not "Tar Paper"? I've never seen any product that didn't come from an auto upholstery vendor that resembled anything in the Home Depot, and I'm in the building trade for 40 years. The old school underlayment has a certain feel and flexibility to it. All I stated was that were better products as far as insulating, ease of installation, and involving Zero petroleum gas off or mess. It's your car, you can do what you want. It's just an opinion......
                                                                                                    Bobby

[Bob Kielar]

Dynamat that's what I used on my 55 Fleetwood and I try to keep my Fleetwood as original as possible. Remember they also used asbestos back in the day.

Keep Cruzin,
Bob Kielar

[39LaSalleDriver]

https://www.homedepot.com/p/1-2-in-x-4-ft-x-8-ft-Southern-Pine-Asphalt-Impregnated-Board-A11230848096/206086210

This is the product I'm talking about. Not what I would call tar paper,  but I'm not in the construction biz so I'm not sure what it'd be called in the trades. I have a habit of wandering through stores like craft and hardware stores just looking at stuff and making mental notes of what things "could" be potentially used for.

[Bobby B]

https://www.homedepot.com/p/1-2-in-x-4-ft-x-8-ft-Southern-Pine-Asphalt-Impregnated-Board-A11230848096/206086210

This is the product I'm talking about. Not what I would call tar paper,  but I'm not in the construction biz so I'm not sure what it'd be called in the trades. I have a habit of wandering through stores like craft and hardware stores just looking at stuff and making mental notes of what things "could" be potentially used for.

Original underlayment is about 1/8" or so thick. Good Luck fitting that thickness around anything. If you're going with jute backing or jute backed carpet on top of that, you're going to have a hard time with the overall added height, and finding your seat holes and anything else underneath an additional 1" of topping. That's why the correct stuff is thin and flexible.
             Bobby

[Tom Boehm]

http://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50000129a~Z5Z5Z5818~P75.00~~~~S5431AN09K74137326380a~Z5Z5Z5~Z5Z5Z50000129A

Hello J., This is what I used on the floors of my 1940 Lasalle. No silver. www.markii.com

[Tom Boehm]

https://pack-n-tape.com/3M-08840-Sound-Deadening-Pads-500-mm-x-500-mm-10-per-case.html?gclid=Cj0KCQiAkZHTBRCBARIsAMbXLhHtftIjJQHP_ToBER6apa9fF9rxVheLhms3TuxDPwxREal6XwC7FTMaArTqEALw_wcB

Hello again Jon, I also used some of this. Again, no silver. It conformed to the contours with a heat gun. I used this on the underside of the transmission cover. It seemed on mine there were two layers originally on the floors. I used this first and the other stuff in the previous post on top. The other stuff looked more authentic. I think the stuff from MarkII is literally tarpaper with a waffle pattern stamped in it.   Tom Boehm