People who buy mobile homes are often stuck with leaky roofs, buckling floors and other problems which, despite warranties, they cannot get repaired, a consumer protection official told Federal Trade commissioners this week.

Even a recent federal law, designed to get the Department of Housing and Urban Development to address the situation, is not working, Robert Hildress teh situation, is not working. Robert Hilgendorf of the New Mexico Attorney General's office told a Federal Trade Commission hearing.

He said officials in his state receive from six to 30 complaints a month. The "social cost of unsafe, unrepaired and unliveable" mobile homes is being borne by the "unfortunate victims" who live in them, Hilgendorf charged.

The problem is especially acute in New Mexico, he said, where many low-income persons can afford no other type of housing.

He urged the FTC to pass a rule it first proposed in 1974 under which all repairs due under a warrnty would have to be made within 30 days, or, in cases where the defect makes the home unlivable, within three days.

In addition, the separate responsibilities of dealers and manufacturers for obeying the terms of the warranty would be spelled out and manufacturers would have to look over the shoulder of dealers to make sure repairs are made if the dealers are responsible.

Miles Kirkpatrick, a former FTC chairman who represented a segment of the mobile home industry at the hearing, said the proposed rules could add $500 to $750 to the cost of a mobile home, an increase he said low-income persons may not be able to afford.

Hilgendorf noted that if a home were financed over a 15-year period, the increase would amount to only a few dollars each month.

The 1976 HUD standards for mobile homes emphasize safety and health rather than quality, said Peter L. Maier, who testified on behalf of the Center for Auto Safety, a Ralph Nader organization. As a result, the durability of furnishings and floors, and the quality of draperies and cabinets is not adequately assured, he said.

The defects stem from the nature of the mobile home industry, Maier testified. He cited human error due to a lack of automation, production incentives that cause workers to try to work too quickly, and the use of unskilled workers employed on a seasonal basis.