Virginia Gov. Charles S. Robb's four-year-old daughter Jennifer has been spending her evenings rolled up in a sleeping bag on the floor of her parent's cramped bedroom. Her own room is mired in plaster and dirt.

The main kitchen down the hall is out of commission, forcing the governor to eat many of his lunches at Chickens, the State Capitol snack bar. And the shower in Robb's bathroom leaks, threatening the main dining room downstairs.

So it goes this summer in the country's oldest continuous governor's residence. Since a team of state workers began renovating Virginia's Executive Mansion last April, the elegant, 169-year-old, gray Georgian home on State Capitol Square has been transformed into an unlivable jungle of plastered dirt, torn-up electrical wiring, leaking pipes and sagging floors.

Each attempt to repair a problem at the mansion has only led to the discovery of unexpected difficulties, and the costs are going through the roof. Once estimated to be a $240,000 affair, state officials now say the renovation job could cost $315,000 or more.

"The plumbing has been in such bad shape that the water is backed up in the bathroom, " said Robb's press secretary, George Stoddart. "The air conditioning is so bad you can't hold any public events in there."

For Lynda Johnson Robb -- the late president Johnson's daughter, who grew up in a mansion where the upkeep was better -- the recent renovation work hasn't been too much of a trial. She has spent nearly all of the summer out of town, either in the family home in McLean, in Texas, or vacationing in England, a spokeswoman said today.

Robb, too, has spent much time out of town, either campaigning for Democratic candidates in such far-off places as Nebraska and Iowa or staying overnight at the National Guard cottage that is reserved for his use at Camp Pendleton in Virginia Beach.

Yet the stoical governor has refused to stay clear of the mansion altogether, largely, his friends say, because of tradition.

"He said he didn't want to move out because this is the oldest living continuous governor's mansion there is and he didn't want to break that," said State Del. Alson H. Smith (D-Winchester) who chairs the legislative subcommittee that oversees the renovation work.

If Robb had known back in April precisely how bad things were going to be, he might have had second thoughts. The repair work was envisioned as a simple matter of refurbishing the governor's second-story living quarters, including installing a new cedar closet and enlarging two of the bathrooms. Then the maintenance crew discovered that the plumbing in the main bathroom, which former Republican Gov. John N. Dalton first complained of, was so backed up that water was overflowing, causing the floor to sag and posing a potential threat to the main dining room below. The pipes were so clogged and corroded, Smith said, that the state had to put in a new plumbing system.

Meanwhile, the electrical wiring had deteriorated to the point that bending some wires would cause their insulation to fall off, creating a potential fire hazard. The air conditioning was so anemic that an entirely new system had to be put in. Final work on the upstairs living quarters, however, should be completed by the end of the week, a spokesman said today.

Throughout the ordeal, Smith said, Robb continually pressured him to keep the costs down.

"The governor's been pounding me over the head about that," Smith said, "But I keep saying that's not Robb's house; he's just going to be there for awhile, for only three and a half more years. That house is the taxpayers of the State of Virginia's home."