AT LAST SOME MEMBERS of Congress are sericously trying to overhaul federal building policies. The Senate Public Works Committee started with a jolt Monday by voting not to consider any nonemergency construction, leasing or major repair proposals from the General Services Administration until new policies and safeguards are in place.

This is a drastic step. While not affecting projects already under way, it does put in abeyance, perhaps for the rest of the year, about 20 projects already submitted to Congress -- including the Government Printing Office's long-debated new plant, now priced at $171 million. The freeze could also delay more than 100 other proposals all over the country that are now in various stages of administrative planning and review. All told, the committee may be holding hostage more than $1.2 billion in building commitments. That should put real force behind their demands for policy change.

The freeze, initiated by Sens. Daniel P. Moynihan (D-N.Y.) and Robert T. Stafford (R-Vt.), was probably precipitated by revelations of corruption in GSA and uncertainty about what may happen when administrator Jay Solomon departs. But questions about the agency's building and property-management policies have been piling up for years. There are particular concerns about leasing, which has become so popular that GSA now pays over $500 million per year to rent almost half of the working space it manages for federal agencies nationwide. Many people have wondered whether buying or building permanent facilities might be a better bargain for the taxpayers. GSA has also been assailed for possibly violating its own urles in some cases -- for instance, by negotiating preconstruction leases for buildings that would not otherwise have been built.

Of course, Congress has had a major hand in all of this -- and not just by failures of oversight. Many members of Congress, past and present, have urged various federal building projects on the agency and encouraged GSA to look favorably on certain contractors and developers. Building a new federal structure, or at least renaming one, has become a common going-away present for departing congressmen. And if a pet prospectus gets stalled by the executive branch or the public works committees, influential lawmakers simply bypass regular procedures and tuck the money into an appropriations bill. Last year the administration asked for $17 million in GSA construction funds. Congress approved $114 million.

One major question, the, is what role Congress ought to play in the federal building business. Before that can be debated sensibly, though, the public works committees have to do what they should have been doing all along: Dig into this multi-billion-dollar subject, identify the problems and recommend more prudent policies. Sens. Moynihan and Stafford and their colleagues have a big job ahead. We commend them for tacking it and urge them on.