My girlfriend paid her contractor the amount quoted in the contract for a re-roofing job. Now about 3 months later they say owes them an additional amoun . They have threatened her with putting a lien on her house. She hasn't gotten any additional paperwork from them for the additional amount. Can they place a lien on her house? The state is Colorado. The contractor says she owes them an additional amount. But haven't backed it up with any sort of documentation. The invoice she was presented with is paid in full They claim she owes them an additional amount based on an insurance settlement. One last question. The contractor would need to prove, say with an additional contract or signed addendum to the original contract that she's liable for the additional amount?