We just had a backup into the basement from the main sewer line. The line was roto rootered and then scoped. The company suggested the line be completely re-lined with the cast in place pipe and quoted 15k for the job. I have a couple more companies coming out today for more quotes. Is this truly necessary or will something like copper sulfate or the foaming root killer do the job? I linked some video/pictures from the pipes below. Thanks for the help.
https://imgur.com/gallery/VuHQtwS
https://imgur.com/gallery/VuHQtwS