Is there any special certification for doing commercial inspections or 4 points, other than being a NACHI member?
You should take the commercial inspection course: www.nachi.org/commercialcourse.htm (free).
You should join the ComInspect Network at the bottom right corner of www.cominspect.com (free).
You should use InterNACHI’s approved 4-Point form www.nachi.org/4point.htm (free).