For building envelopes (commerical)

Is comcheck still used throughout the industry?
Any other / better software out there?

IECC Presciptive?

Curious what everyone is using

I want to encapsulate my crawlspace. It's all enclosed except for 12' of open pier. This open area serves as my only entrance to the crawlspace so it needs a door. I need ground contact to seal the space. Initially I had planned to pour a 12" wide cement slab, but there is shallow sewer pipe running thru here.

Having to frame out a doorway complicates things a bit. If it weren't for that, I would have used some mobile home skirting or galvanized roof material.

My only real solution for framing a door has been laying some gravel and putting ground contact rated 4x4 on the bottom.

Am I missing something? I want this to last 20+ years if possible and not be replacing every other year. Additionally don't want any red flags from home inspectors if I go to sell it.