All I know is in my tC I had 100 sq ft and I did my trunk, floors, doors, and rear paneling and barely had enough. I would just hit what I thought would be most important (i.e. doors, wheel wells) then if I didn't have enough, I would be covered till I had enough dough to buy more. BTW you can't have too much dampening so buy as much as you can afford.
I have a big Chevy truck and I used over 2 rolls. That only did 2 layers on the floor, rear wall, and doors. If and when I get the Dayton 12s installed, I am surely to need the headliner done too. It all depends on what you want to achieve, but dont overdo it just to do it, I only add matte when needed. If it isnt broke, dont fix it.
BTW...I would suggest ordering Ensolite from Rick as well. The combo of bxt and ensolite is excellent at keeping vibration and noise to a minimum.
I opted not to do the floor, I think most sound deadening i.e. asphaultic or butyl based work mostly on weight, so the other areas are probably more important in my estimation, most cars already have a little bit of asphaultic material baked into their floors. However maybe 1 layer, but I would expend most of my material on the doors, and wheel wells. Some carpet padding/insulation never hurt either for the higher pitched noises. Dense is the key.
I used Grace Ice and Water guard, 55$ for 100 square feet. Same specs as Original Dynamat with a plastic liner instead of Aluminum. Or if I had know, I could have gotten Grace Vycor which is the butyl based version, similar in specs to Dynamat Extreme for the same price per 100 square feet. That's why I didn't use an entire roll. I did 2 layers, omitted the weighted dampening on the floors because I don't think the weight helps on the floors... butyl might be different, but I'm not convinced since the floors already are so heavy... maybe a foam barrier...
Personally it would come down to weight for me. If you don't care about weight added by dampener i would definitely pay the extra $80-$100 to do a couple layers on the floor. Is it as effective as say the doors or the trunk lid? No, but is it noticeable? yep, if you use good stuff (raamat BXT, dynamat extreme, Hushmat, secondskin) and use a few layers you will definitely benefit alot by doing it. In my 01 Mustang GT i didn't care about weight so i dumped 3 rolls of raamat in it and 2 layers of closed cell foam EVERYWHERE, and up to around 8 layers total in each door from the outside skin to the inside skins plus some. Even with my 3 JL 10w3's pumped with 1500w of US AMPS power there wasn't even ONE rattle in the car and i'm talking with ONLY the subs turned on up to full tilt without any interior speakers on for a true listen to what the car sounded like. Not having 1 rattle coming from the car (literally) with your system cranked
is a hell of an experience. I wish i didn't care so much about adding extra weight to my new car or i'd be dumping TONS of dampener in this car
Wind noise is primarily caused by good/bad seals. What kind of car is it? I mean sheer noise is something that closed cell foam, or equally good (and cheaper) jute can take care of. If it's coming through the window area, firewall, it will be tough to get rid of. But seal everything, toss out the cheap plastic that seperates your car's window shell from the interior plastic, and cover that with some thick deadening mat. Any little plastic piece that could possibly rattle, tie that down with mat. seal anything and everything you can see the outter shell of the car, you want to try and get your car as much of a sealed enclosure.
When it comes down to sound dampening/deadening, your car, nor physics cares what brand, whether you pay 500$ or 50$ the weight added to lower the resonance frequency of the panel is what counts. look at what the material is made of and it's ratings, you'll find it's all the same stuff, in home audio, they often will use lead sheets, or 3 layers of MDF... it's all about weight with mat.
To block higher frequency noise, you need air pockets, and the more the better. Closed cell foam is used in some of the more expensive treatments, but in all the best home theatres I have helped install, we used compressed fiberglass mat, which is rigid so not applicable for a vehicle use. However it is the fiberous nature of fiberglass, with air pockets that blocks the sound. If you look on the interior of any car, you will find some fiberous jute like material (not rubber, and not closed cell foam). Take apart a lexus, Acura, bmw, mercedes, and you will find this "jute" type material. You'd think if closed cell foam was the way to go, more manufacturer's would be using it, but I've never seen it in a car. In fact some closed cell foams, like the hardening window insulation foam will act as a transmitter of noise, making it worse. Soft, fiberous, like the insulation we use in sub boxes, except that stuff is way too light, dense fibers is the key. I think the Jute made a bigger difference than any mat install I have ever experienced.
You can see in this picture, top is the fatory "jute" and below is the material I am using.
example of door:
What I would reccomend for the floor instead of any asphaultic or butyl based dampener:
You can see here the patches of black, these are factory asphaultic sheets that honda uses:
You can sort of see that honda has place asphaultic sheeting under the front 2 seats, so it might not be a bad idea to put another layer or two, but I opted for just the carpet padding.
There are 3 ways to block sound, deadening (weight), absorption (air pockets in fiberous material), and sealing of air passage between the exterior and interior.
i spent about 1000+ on sound dampening material.. i forgot how much dampener that equates to be it's serveral hundred sqft. The most road noise is through the fire wall and doors. Dampening my floors with just mat did very little. You'll be better off with some sort of sound absorbing foam. I used luxury liner.
Ocelaris, doesn't that material absorb water? I live in Canada and the inside of the car frequently get's wet because of the snow that is dragged in the car from going in and out of the car. The carpet never really gets dry before spring.
I'm scared to use that and have rust all over after 1-2 years...
You make a barrier seal with the asphaultic or butyl based mat. You don't put the carpet padding where it can get wet. Sound and heat/cold ironically are very similar in the way you treat them. First make a good seal, second use fiberglass or other "air pockety" material to dissipate noise. What is good for keeping your interior warm inside, is good for keeping sound out (canadian reference, assuming it's cold). Just make sure not to plug the holes in the bottom of the outer skin of the door that exist for water to drain out of. It is assumed water will get in the outer skin of the car, but you can stop it from getting in the inner skin, which is before the fiberous material, and then door.
so you have from outside to inside.
loud -> paint-> outer shell -> window -> inner shell -> mat -> jute -> plastic door piece -> quiet
Mercedes, BMW etc... just use heavier sheet metal, better weather stripping seals, and more fiberous materials.
I used more than three rolls of Raammat, plus I also lined the entire floorpan, as much of the firewalls as I could, the inner doorskin & the inside of of the outer doorskin with mat AND ensolite. This was all in a regular cab truck . The ensolite made an incredible difference imo. MUCH quieter ride now. I can't recommend it enough...
This forum has been pretty good about listening to my rant about the generic brands of mat, some forums I've contributed to, people get very defensive and go to insane lengths to try and prove the generic stuff is useless. But it's not, it's half the cost of even the bargain brands, so for half the price, you get twice as much.
The only difference I have seen in the same thickness mat, is the aluminum backed ones are like 25mil and the grace, ice and water guard is 23mil, that aluminum being 2mil thicker... now a mil is like 1/100th of an inch, so the weight isn't much more, but the structural rigidity of the aluminum is significant. That is the only thing I could justify by going with the raamat, fatmat etc... bargain brands. I would never pay for dynamat which is like 4x the cost of raamat for the same thing.
Unless you are going with cascade multi layer materials which cost like 10x the generic mats (ice and water guard etc...) I would stick with the bargain brands, or the generic. Whatever mat you go with, definetly try the jute. For 20$ at home depot you can get more than enough to do your entire car, doors, ceiling, floor, sides, everything.
I spent 60$ on 100 square feet of the ice and water guard, and like 20$ on jute, and I only ended up using a little more than half of the mat, did my wife's car with the rest.