How liable are landlords when it comes to ADA accommodations?

A purely theoretical question, as I’m still in my learning phase of becoming a real estate investor. But I’m reading through a lot of books and keep coming across the Americans with Disabilities Act, and how a tenant may make alterations to your rental unit to accommodate their needs. While I’m obviously fine with that regardless of the law, my immediate concern comes to how much control I have over the temporary renovation to my unit, and how liable am I should the renovation be done wrong. Let’s say the tenant pays their uncle Joe to install a ramp because he’s seen it done on TV once before and doesn’t think it’d be all that hard. A month later the tenant or anyone else is waking on the ramp, it breaks, and they get injured. Can the landlord be facing a hefty lawsuit in this scenario? Is the landlord allowed to approve or disapprove who does the renovations to the unit when they need to meet the requests for a tenants ADA accommodations? Anyone have any horror stories or tips/advice on handling this issue?