We were referred to a concrete contractor by a friend. We hired him and he began the job a few days later. The written contract has very detailed specifications for the job. The job was for $8500 and the "contractor" was given $3000 before starting. When we went to review the job on completion, the "contractor" did not follow the contract in many areas. The concrete was much poured much thinner than agreed and will likely crack in a few years as its in an area where garbage trucks drive over 6 times a week. The job is worthless to us because it will cost more money to fix it to spec than leave it to crack quickly. After the job, we found out the contractor is not licensed. We have not paid the "contractor" more than the $3000 already given. The concrete supplier is threatening us with a mechanic's lien for the $2500 in concrete he supplied the "contractor" and he is still withing his 20 days to give the preliminary notice. I suspect he will give it within the 20 days. The concrete supplier is not licensed as a contractor either. The contractor supplier started and finished the job in 1 day. We did not know who the concrete supplier was or the amount he was charging until after the job was completed (but within 20 days). Can the concrete supplier file a mechanic's lien against us?