The Ennis House, Frank Lloyd Wright's concrete-block landmark that was red-tagged after record winter rains four years ago, has finished one phase of its rehabilitation, including repairs to a monumental retaining wall that had crumbled away.

"As part of that work, the motor court was taken out and new structural frame put up beneath it," said Linda Dishman, chairwoman of the Ennis House Foundation, the nonprofit group that owns the property. "All of the concrete blocks that fell down have been replaced."

The 1924 house is the fourth and last of Wright's concrete block residences in the Los Angeles area. Though innovative and visually compelling, the "textile blocks" that define the architecture at Ennis House had serious flaws. Metal supports rusted from within. The concrete mixture, which included decomposed granite from the site, deteriorated under rain and pollution. The system was never as structurally sound as Wright had expected, and even historical photos show buckles in the wide motor court and south wall.

Nevertheless, since the house was built, it has dominated a promontory in the hills near Griffith Park like some sort of Mayan ruin.

The property's last private owner, Gus Brown, purchased the house in 1968. He later created a nonprofit foundation that raised money by offering tours, selling souvenirs and renting the landmark for film productions. The home, which had long been a challenge to maintain, suffered a setback when sealer intended to protect the concrete blocks only hastened their disintegration. The 1994 Northridge earthquake further weakened the structure.

Record rainfall in late 2004 and early 2005 led to severe buckling of the south retaining wall. The National Trust for Historic Preservation in 2005 listed the site as one of America's 11 most endangered places. The nonprofit World Monuments Fund in 2004 and 2006 placed the Ennis House on its list of the world's 100 most endangered sites, alongside some of the Mayan ruins that influenced Wright's design.

"After Gus Brown died in 2002, the people who continued on the foundation were well-meaning, but it was hard to move the project forward," Dishman said of the ongoing need for repairs. "We were in danger of losing FEMA funding, and with the rains of 2005 it was clear that without a significant intervention there was danger of losing the house."

A renamed and reorganized Ennis House Foundation secured additional grants from the Federal Emergency Management Agency, as well as a $4-million construction loan. The project calls for stabilizing the house, replacing the roof, repairing an ornate fireplace mosaic and conserving stained glass windows.

One issue still up in the air: public access. After Brown's death, tours and events at the site tested the patience of neighbors.

"All of this was illegal," said Frank Mosi, who lives nearby. "The zoning here is for single family residences, not for museums, or tours, or events to raise money."

This time, the foundation has reached out to local residents.

"They were terrific," Mosi said. "They started contacting the neighbors, and they wanted input. They talked about transparency and doing the stabilization required to get the red tag taken off."

Some neighbors have suggested that when the landmark is ready to reopen, the foundation should offer tours that are limited in number and free. Dishman said the foundation is formulating a proposal to present to neighbors.

"We'd like to have public access," she said. "A lot of public money went into the house, and we'd like to see if it's possible to have public access in a way that is respectful of both the neighbors and fans of Wright's architecture."

home@latimes.com