sound deadening: sq footage amount for 3dr

[goku87]

and one more question: is there a major benifit from doing the roof?

i've read that it varies depending on vehicle, and i was thinking, being a hatchback the roof is probably pretty well reinforced so it might not have that much vibration to begin with.

[WolfWings]

Originally Posted by goku87

and one more question: is there a major benifit from doing the roof?

i've read that it varies depending on vehicle, and i was thinking, being a hatchback the roof is probably pretty well reinforced so it might not have that much vibration to begin with.

Our roof is a single, unreinforced expanse of sheetmetal. The headliner has large bars of styrofoam that keep it tensed and add some pressure to the roof-panel, but it's one giant metal cymbal. Laying a single layer of good-quality sound dampener is worth it, IMHO, especially if you go for something that's highly cost-effective like RaaMAT. I bought two rolls of it, and 6 yards of their closed-cell foam, went the 100% sealed route on both doors.

The real trick on doors is stick some mat down, make sure the windows work still, knock all over the door, stick more mat wherever it still goes 'ting' instead of 'thud' and keep going until your knuckles are sore or until your run out of mat. Only downside: Your doors will weigh a full 50% more than they started with, so they're noticably harder to 'get going' to pull closed. I only did my drivers-side door before winter set in and am about to finish up the passenger-side door, I'll get a recording of the noise of slamming one door versus the other, and knocking on the door-panel all over to demonstrate the difference. As for the back area, having a daring friend with a good ear willing to ride around in the naked rear to listen for where the noise comes from will let you find out where to layer more soundproofing down in a hurry.

Side-tip if you don't have to worry about power locks and what-not: A tube of silicone sealant for exterior windows, and a couple of the giant-sized 'for sale' signs from wal mart are excellent for putting down a semi-permenant barrier to fully seal your door with soundproofing. Careful trimming, bead of silicone, go grab a sandwich while it sets up a bit, work the locks and door-handle repeatedly to make sure it's not jammed anywhere, then go to town laying down a double-layer of narrow strips of the sound dampener, then a layer of the foam, good to go.