what to use under carpet?

[new2bmw]

what can i use on the floor under the carpet to help protect against rust? i was thinking maybe rockerguard or rubberized asphalt undercoating? just worried about bleeding through the carpet. any suggestions ? its been cut and welded and the floor is now rust free, i need to keep it that way.
Thanks ,sorry in wrong section can someone move to general discussion please
Larry

[ak96ss]

Undercoating, but try to get the same sort of stuff BMW uses - it is much thicker than you'll get out of a rattle can. Almost the same consistency as Rhinoliner. Which would be an awesome undercoating if you can get it done... the Army uses it on some vehicles...

http://www.rhinolinings.com/about.php?id=4&news_id=11

[HST]

Look at por15, http://www.por15.com Their stuff is expensive, but good. It sounds like you want to put something on the inside of the car, but I would put something under the car to protect from rust. Inside the car would not do much good unless you have a leak somewhere.