Appellant instituted this action to foreclose a mechanic’s lien and to' recover the balance due on a construction contract. The trial court granted summary judgment in favor of the respondents. We reverse.
In February of 1975 appellant contracted to construct respondent’s home. The agreed contract price was $28,528.00 of which $26,000.00 has been paid. The respondents have refused to pay the balance of the debt alleging the unenforceability of the contract under Section 56-1545.31 et seq., Code of Laws (Cum. Supp. 1975), as well as defective workmanship. The trial judge, granting summary judgment because appellant did not have a license when the contract was executed, construed Section 56-1545.43 to render the contract unenforceable.
Section 56-1545.37 requires that all residential home builders be licensed annually in compliance with the licensing standards of the Act regulating home builders, “except that any person engaged in residential home building on or before July 1, 1974, shall be duly licensed . . . without examination, after paying the required annual fee by submitting to the Commission within a period, of twelve months after such Commission is established the following: (a) An affidavit showing that such residential home builder has constructed a minimum of one residential home within a year prior to July 1, 1974; and (b) An executed bond . . .” (Emphasis added.)
Respondents assert a construction of the statute, based on the legislative intent to require proof of financial responsibility, to mean that the appellant should have obtained a license immediately after July 1, 1974, in order to legally continue to operate his business. Yet, the statute in plain, unambiguous language allows an established residential home builder twelve months in which *130to legally continue his operation and obtain the requisite license.
The following provisions leave little room for interpretation. “All residential home builders shall be required to be licensed . . . except that any person engaged in residential home building on or before July 1, 1974, shall be duly licensed . . . without examination . . . within a period of twelve months . . .” (Emphasis added.) The exclusion modifies and qualifies the basic licensing mandate. Such provisions which insure orderly transition periods for the implementation of new legislation are not uncommon. There is no evidence that appellant did not come within the purview of the exception when he entered into the instant contract. Having twelve months within which to obtain a license, appellant as an established residential home builder could operate during the period allowed by the statute.
“When, as here, the statute is plain and unambiguous, it becomes the duty of the court to apply it literally because the legislative design is unmistakable.” Martin v. Ellisor, 266 S. C. 377, 381, 223 S. E. (2d) 415, 417 (1976). Any other construction of the statute would be amendatory; certainly it is not the province of this Court to perform legislative functions. Coker v. Nationwide Ins. Co., 251 S. C. 175, 161 S. E. (2d) 175 (1968).
The legislature specifically enunciated in Section 56-1545.43 the legal sanctions attendant to violation of the chapter:
“Any residential home builder who undertakes or attempts to undertake the business of residential home building without first having procured a valid license which has neither expired or been revoked required by the provisions of this chapter or who knowingly presents to, or files false information with, the Commission for the purpose of obtaining such license shall be deemed guilty of a misdemeanor and upon conviction, shall be fined not less than one hundred dollars or imprisoned for not less than thirty days.
*131“No residential home builder who does not have the license required herein may bring any action either at law or in equity to enforce the provisions of any contract for residential home building which he entered into in violation of this chapter.
“Whenever it shall appear to the Commission that any residential home builder has or is about to violate the provisions of this chapter the Commission may in its own name petition the court of common pleas of the county wherein the violation occurred or is about to occur to issue a temporary restraining order enjoining such violation of this chapter pending a full hearing to determine whether or not the injunction should be made permanent.”
Appellant steadfastly maintained, and couched his exceptions on the proposition, that he was not in violation of the Act. When appellant entered into the contract, in the instant case, he was within the statutory exception and, furthermore, he completed construction of the residence within the twelve month period. There was no legal infirmity in the contract at its inception or at its completion when the contractual obligation became due.
The legislature intended only one penal sanction for the violation of this Act: a misdemeanor fine as provided in the first paragraph of Section 56-1545.43. The second paragraph is merely a self-enforcing provision which precludes suit on any contract “entered into in violation” of the Act until a license is procured. Appellant was not in violation of this Act when he entered into, or completed, the instant contract and he subsequently acquired a license, prior to this action.
There is yet another paramount consideration which dictates our resolution. A statutory construction which retroactively deprives a party from pursuing his rights pursuant to a legal contract is not only manifestly inequitable, it is an unconstitutional impairment of contractual obligations. S. C. Constitution, Article 1, § 4 (as *132amended); U. S. Constitution, Article 1, § 10; Henry v. Alexander, 186 S. C. 17, 194 S. E. 649 (1937); Martin v. Saye, 147 S. C. 433, 145 S. E. 186 (1928); Smith v. Jennings, 67 S. C. 324, 45 S. E. 821 (1903). Constitutional constructions of statutes are not only judicially preferred, they are mandated; a possible constitutional construction must prevail over an unconstitutional interpretation. Casey v. S. C. State Housing Authority, 264 S. C. 303, 215 S. E. (2d) 184 (1975); Thompson v. Hofmann, 263 S. C. 314, 210 S. E. (2d) 461 (1974); Peoples National Bank of Greenville v. S. C. Tax Commission, 250 S. C. 187, 156 S. E. (2d) 769 (1967).
It is clear that the appellant was not in violation of the Act when he entered into the contract, when he completed the contract, or when he instituted this action. To conclude he is not entitled to collect a legal debt owed to him, would be manifestly unjust and constitutionally defective. We, therefore, reverse the order of the trial court and remand for such proceedings as the parties may desire consistent with this opinion.
Reversed and remanded.
Lewis, C. J., and Littlejohn and Rhodes, JJ., concur. Gregory, J., dissents.