for front doors I use either this Peel & Seal or Fat Mat

https://www.lowes.com/pd/Peel-Seal-Instant-Waterproof-Repairs-6-in-x-25-ft-Aluminum-Roll-Flashing/1018733

for body panel I combine them with fiber glass roll

http://www.homedepot.com/p/Owens-Corning-R-30-Unfaced-Insulation-Continuous-Roll-15-in-x-25-ft-RU70/202585906