Me. Stat. tit. 38 § 958
Any existing building or structure or use of a building or structure lawful March 19, 1974, or on the date of any subsequent amendment of this chapter or of any regulation adopted hereunder, may continue although such a use of a structure does not conform to this chapter or the regulations adopted hereunder. Any existing building or structure may be repaired, maintained and improved, but an existing building, structure or nonconforming use may be extended, expanded or enlarged only by permit from the commission. A nonconforming use, other than a single family residential use, that is discontinued for any reason for a period of one year is deemed abandoned and may not be resumed thereafter except in compliance with the requirements of this chapter. [1995, c. 171, §9(AMD).]
If, as a result of flood, fire or other casualty, the value of a nonconforming building or structure is reduced by more than 75%, it may be rebuilt and the nonconforming use housed therein may be continued only by permit from the commission. If a nonconforming building or structure is decreased in value less than 75% by flood, fire or other casualty, it may be rebuilt in substantially the same location and in the same size without a permit from the commission, even though it would otherwise violate the requirements of this chapter, provided that the rebuilding shall be commenced within 12 months of the casualty. [1979, c. 459, §1(NEW).]
If 2 or more contiguous lots or portions thereof are in single ownership on or after March 19, 1974, and if all or part of the lots do not meet the criteria of lot width, area, frontage or other measures required under this chapter or if a building thereon could not meet the aggregate requirements established by this chapter, the lots involved shall be considered to be one parcel for the purposes of this chapter. [1979, c. 459, §1(NEW).]
To avoid undue hardship, nothing in this chapter may be deemed to require a change in the design, construction or intended use of any building or structure with respect to which substantial construction was legally carried out prior to March 19, 1974 or the effective date of any amendment to this chapter. An intended use within the meaning of this section is any use for which such a building or structure is designed as evidenced by the construction or by plans or specifications in existence as of March 19, 1974 or, in the case of any intended use affected by any amendment to this chapter, construction, plans or specifications in existence on the effective date of that amendment. [1995, c. 171, §9(AMD).]
38 M.R.S. § 958