S.C. Code Ann. § 48-39-290
(A) No new construction or reconstruction is allowed seaward of the baseline except:
(B) Construction, reconstruction, or alterations between the baseline and the setback line are governed as follows:
(1) Habitable structures:
(a) New habitable structures: If part of a new habitable structure is constructed seaward of the setback line, the owner must certify in writing to the department that the construction meets the following requirements:
(b) Habitable structures which existed on the effective date of Act 634 of 1988 or constructed pursuant to this section:
(iv) Replacement of habitable structures destroyed beyond repair due to natural causes is allowed after notification is provided by the owner to the department that all of the following requirements are met:
a. The total square footage of the replaced structure seaward of the setback line does not exceed the total square footage of the original structure seaward of the setback line. The linear footage of the replaced structure parallel to the coast does not exceed the original linear footage parallel to the coast.
b. The replaced structure is no farther seaward than the original structure.
c. Where possible, the replaced structure is moved landward of the setback line or, if not possible, then as far landward as is practicable, considering local zoning and parking regulations.
d. The reconstruction is not seaward of the baseline unless permitted elsewhere in Sections 48-39-250 through 48-39-360.
(2) Erosion control devices:
(b) Erosion control structures or devices which existed on the effective date of this act must not be repaired or replaced if destroyed:
(3) Pools, as defined in Section 48-39-270(12):
(c) If a pool, existing on July 1, 1988, is destroyed beyond repair, as determined by the department pursuant to Section 48-39-270(11), it may be replaced if the owner certifies in writing to the department that:
(d) If a pool is not destroyed beyond repair as determined by the department pursuant to Section 48-39-270(11) but the owner wishes to replace it, the owner may do so if:
(C)
(1) Notwithstanding the provisions relating to new construction, a person, partnership, or corporation owning real property that is affected by the setback line as established in Section 48-39-280 may proceed with construction pursuant to a valid building permit issued as of the effective date of this section. The person, partnership, or corporation may proceed with the construction of buildings and other elements of a master plan, planned development, or planned unit development notwithstanding the setback line established in this chapter if the person, partnership, or corporation legally has begun a use as evidenced by at least one of the following:
(b) There is a master plan, planned development, or planned unit development:
(D) Special permits: