A special House commission evaluating the Capitol Hill page system yesterday recommended that the minimum age for pages be raised to 16, that they be housed in a supervised dormitory and subject to a code of conduct.

The commission chairman, Rep. Bill Alexander (D-Ark.), in announcing the panel's conclusions, also said he thought the pages had gotten a "bum rap" because of highly publicized allegations that members of Congress had used some of the teen-agers for sex.

Alexander said yesterday he believed the pages were "hard-working, loyal, patriotic and God-fearing citizens." He said he had talked to 20 to 30 pages during the commission's work and none of them had raised any complaints about sexual misconduct by a member of Congress.

At least three former pages made the allegations, which have been investigated by the Justice Department and the House ethics committee. The Justice Department has found no evidence to support the allegations, and is expected to discontinue its probe, informed sources said this week.

The House ethics committee, under newly appointed special counsel Joseph A. Califano Jr., is setting up a separate, independent investigation into allegations involving sex and drug use on Capitol Hill. The Justice Department is also looking into possible violations involving drug abuse.

Nevertheless, the commission said in its report that it was concerned about the adequacy of supervision of the 100 pages, who come to Washington from around the country.

In a 14-page report submitted yesterday to House Speaker Thomas P. O'Neill Jr., the commission recommended that the pages -- now some as young as 14 -- be at least 16 years old and in their junior year of high school, and that they work no more than five months.

The commission also recommended that the House set up a Page Board, consisting of the House leadership, to centralize management of the page program, which is now dispersed among a number of offices and committees.

The commission suggested that two floors of House Annex Building No. 1 at New Jersey Avenue and C Street SE -- which once was a hotel for members of Congress -- be renovated by next month to provide a central residence for the pages. Many of them have been living unsupervised in their own apartments.

According to the commisson report, the cost of renovating the annex building would be about $325,000, which would be offset by rent from the pages, who are paid $700 a month.