N.C. Gen. Stat. § 44-38

All claims shall be filed in the office of the clerk of superior court in the county where the labor has been performed or the materials furnished, specifying in detail the materials furnished or the labor performed, and the time thereof. If the parties interested make a special contract for such labor performed, or if such material and labor are specified in writing, in such cases it shall be decided agreeably to the terms of the contract, provided the terms of such contract do not affect the lien for such labor performed or materials furnished.