Description of key points during my two fan installations on my 08″ Dodge Sprinter.
Measure location desired for fan
Triple check measurements
Put bag or tarp under cutting area so you can protect van from metal shards=rust if not properly cleaned out
Tape off cutting area
Drill pilot holes in your four corners that are large enough to fit your jigsaw blade
Insert blade into one of said holes & begin cutting
Sand down sides of hole if you’d like
Install butyl tape onto outside area of roof cut &/or under plastic fan frame that’ll rest on the roof. Make sure it is enough butyl tape
Use self tapping screws to drive fan down into van. Use boards or a wooden frame on the other side of screws to help build a strong anchor for the whole fan instead of just into the roof (Unless you put nuts on the other side)
Seal with something like Sikaflex 221 or whatever you’d like.
Seal screws used to drive fan down also to prevent corrosion & possible water intrusion.
Done. Have fun!
If you have the time please take a look at some of these organizations & charities that help military members with Post Traumatic Stress Disorder (PTSD), transition to the civilian sector, & delivering free hygiene/health & comfort items to them while deployed. Thanks!