I'm gearing up for a major teardown in early August. (engine out and swapped, engine bay degreased/repainted; replace tranny and re-seal underbody)

I'm considering using some kind of rubberized asphalt patching compound as undercoating. Also considering using this as final seal on the floors over paint/Q-pads/ inside the car.

Any reason this wouldn't be a good idea. Flammability? Releasing gasses over time? Durability? Gets pretty hot in Kansas so don't know if the interior would smell like a road repair project every time it warmed up, that would be bad.

Seems like this stuff should protect everything and help dampen sound just fine for a lower $ than the specialty products.

Opinions?

This stuff would be everywhere so if I have to go back and remove it it would be the mother of all pains. Trying to avoid an oversight.

Got the idea from a VW van resto site.

http://www.bulley-hewlett.com/VWindex/index.html

Thanks all,

-Mario E.
Lawrence, KS