Yes the Amish are known for quality work at a great price but this is not always the case and there are major reasons why they can do it cheaper which could see you sued and loss of your home.
When hiring an Amish Crew you must do Due Diligence and realize the following.
1. They do not pay their crews Social Security Taxes . Amish are exempt from it as community takes care of their own
2. The Amish Crews do not follow OSHA Occupational Safety and health Administration Codes that's why there are deaths of Amish on jobs every year higher than standard crews.
3 . They are not covered by Workmen Disability Compensation/ just look at this underage boy working on a roof with his father
4. They often do work without getting proper permits and inspections as my Penn Hills Neighbor found out they had to rip off his new porch and rebuild it properly with thicker columns.
5# The man who brings them to the job site often underpays them for the work they do
6# Often underage children are brought on job to do dangerous work
So as you can see all the above regulations allows them to offer a lower price but you do not always get quality work.
Typically an outsider hires them and then offers their services to you he brings them to jobs etc.
Not the way you want to do it you want to deal directly with the Amish.
Know that if one of the Amish workers gets hurt on your property and its serious you can get stuck paying all their medical and disability expenses and your home owners insurance can deny your claim
Because you did not properly hire a registered crew working with permits. The Amish take care of their own but not always . Their are some phony Amish crews out their as well
Plus their are Ex Amish and Mennonites doing work who do not qualify under the exemptions and must follow all rules of a conventional contractor.
Before you hire any Amish crew check with you local code authority's and check with your home owners insurance to make sure your covered if something goes wrong.