I am the sub contractor for a commerical building. We recieved a blueprint and bidded on the project. On the blueprint there were 18 doors. My company did miscount the doors and wrote 12 doors on the contract. The owners and contractors both signed off on the contract with 12 doors instead of 18. We began work and realized this mistake and both parties agreed to 12 doors of work. The owner told us to do the 6 extra doors. Now the owner refuses to pay us for the extra 6 doors and door handles. Which is around $1,500 over the contract price.
It depend on the terms of your contract with the GC/owner. There may be terms under which they effectively denied you from recovering from an error that you caused. However, if your bid clearly said 12 doors, and the resultant contract incorparted that quote, then I would say that you have a strong argument for additional compensation. If the GC drafted a subcontract form which explicitly parroted yout quote for only 12 doors, I think your argument is even stronger. Independent of the contract language, you would certainly have an equittable argument for unjust enrichment/quantum meruit (that is, the GC/owner are unfairly recieving a benefit in excess of what the doors which were negotiated). Did you request the change order in writing before installing the 6 extra doors?
Was the Owner a party to the contract? From your description I assume that a formal Change Order was not executed. Was there any email confirming the Owner's direction? Ultimately, if the extra work was completed and incorporated into the project, you would have a valid lien claim as well as Quantum Meruit (value of work performed). Given the dollars that are involved I would strongly suggest a meeting with all principals to reach an agreement and avoid litigation which, from an economic standpoint, would not be practical.