Inspectors twice warned a contractor repairing a General Services Administration warehouse in Fairfax County to remove heavy debris from the roof before a portion of the roof collapsed last week, according to John F. Galuardi, GSA regional administrator for this area.

Responding to questions yesterday, Galuardi said reports written by the inspectors show they informed the roofing repair company several days before the collapse and again the day before the collapse that the debris, the material from the roof being repaired, was too heavy and should be removed.

The warehouse, in Franconia, is used for storing furniture and supplies purchased by GSA for use by federal agencies. A segment of the one-million square foot roof caved in over an unloading dock July 27, causing an estimated $100,000 in damage and minor injuries to two workers.

Beiro AA Construction Co. of Alexandria had been hired by GSA to repair the weakened roof structure and stop leaks at a cost of $3.2 million. GSA also hired Gerald B. Curtis Associates, a private consulting firm, to monitor the job for the agency.

GSA attributed the collapse at the time to the debris left by the Beiro firm on the roof. The Beiro firm has not responded to telephone calls made to obtain comment.

In addition to the written reports, the inspectors, who work for the Curtis consulting firm, took a photograph of the materials on the roof several hours before it collapsed.

GSA yesterday issued a press release announcing that the agency has directed the Beiro firm to replace the damaged portion. Galuardi said GSA takes the position the repairs should be done free of charge and will defend that position in court, if necessary.