# Tips for laying multiple layers of sound-deadening material?



## josby (May 8, 2011)

I'm planning on putting down two layers of RAAMmat BXT II in my car...well, maybe not the entire car, but the large areas at least. Any tips from you guys who've done this a lot? In particular, tips for easily figuring out which places two layers will cause issues with the interior fitting back together properly, and also tips on how to find the holes where the interior clips need to go back into?

Thanks!


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## t3sn4f2 (Jan 3, 2007)

Here's one.........DON'T DO IT! One layer on the large un-supported areas, then some ccf, then some mlv. Search around here for a more detailed procedure.


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## jcollin76 (Oct 26, 2010)

^+1
This isn't one of those 'more is better' things. Cover the large areas as said above. Seal of large open areas with tin flashing or wire mesh with mat on both sides. Make sure your doing both the inside and outside skins in the doors. Cover small holes with your mat (not clip, drains, or mounting holes). Leave a solid inch to inch and half from mounting locations. Put mat on the back side of your removed panels. Cover all areas with ccf like ensolite like mentioned above. To make sure nothing is visible, like on your doors, place tape next to your panels before you remove them, so you know where the edge is. Etc.. lots of good info

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 on here, Raamaudio site, etc. Nothing wrong with being thorough, but you get to a point of diminished returns, and your wasting money.


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## Niebur3 (Jul 11, 2008)

^Yep!!!


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## Briznow (Mar 19, 2008)

Read this website: Sound Deadener Showdown

Where you buy the stuff is entirely up to you (although Don is a great guy who sells quality stuff), but you should read each product heading so you more fully understand the specific applications for each product type.


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## josby (May 8, 2011)

Those are some good tips that I hadn't heard before - leaving a little distance from mounting locations, putting mat on the back of plastic panels, and marking the exposed spots of the metal with tape before removing panels...thanks!

As for only doing one layer...has anyone seen any data to support this? Like, decibel readings of a car with just one layer, then the same car again with two? Or, even just the subjective experience of hearing a car with one layer, then hearing it again after a second layer has been added? Without that, it seems like it'd be hard to know whether two is really worth doing or not. Of course, "worth" is always relative anyway...but it seems to me that road noise is the biggest enemy of quality sound in a car that's driven daily, so why not err on the side of caution? 

Of course, you might say "well then, why not four layers? Or six?" but at some point the interior is surely not going to fit back together right and that's a sacrifice I'm not willing to make...but an extra $100 for a second layer of mat doesn't seem too bad if it might lower the noise floor a couple more dB. Am I wrong?


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## josby (May 8, 2011)

Briznow said:


> Read this website: Sound Deadener Showdown


 Sweet, I have not seen that site before...reading it now, definitely plan to read it thoroughly - this job is going to be a pain in the ass and I want to do it as well as I can


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## jcollin76 (Oct 26, 2010)

Reading that will answer a lot of your questions.

I can't speak to being in a vehicle with one layer, then adding another to compare. What I can say is I have a truck, 08 silverado crew. Pretty quiet with the ltz package, but still a truck. It has 33 nitto trails, duel flow master exhaust, which add to road noise greatly. I have a single layer of damp pro on most everything, other than the roof. I did many of the tricks I listed as well as others and had very good results. I drove the truck with no stereo for 4 months and got to know the sound of it very well. Lol it's no Cadillac, but anyone who owns a truck and rides with me is amazed.


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## Briznow (Mar 19, 2008)

You also have to bear in mind that, regardless of how much product (whether it be dampener, blocker, etc.) you manage to fit under your carpet and trim, there will always be a limiting factor in determining how quiet your interior will be. In most vehicles, this limiting factor is the glass.

Imagine a large square room made of 12" thick steel on all sides. Now imagine you have a 2' x 2' area in each wall that is tissue paper. How much do you think all that steel is going to help?

Obviously this is an extreme example, but you get the point I'm driving at.

Another major factor is the type of tires you have on your vehicle.


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## josby (May 8, 2011)

Yeah, that definitely changed my thinking on the subject...it sounds like even one layer isn't really needed, in the sense I was thinking of a layer (covering as much of the surface as possible with mat), but rather just squares of it in the middle of panels that can vibrate, then cover everything with CCF then MLV. Hmmmmmmm....much to think about.


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