Flaws in the original construction were the cause of a mishap at Windemere Nursing and Rehabilitation Center when a section of porch roof collapsed Wednesday morning while workmen were repairing windows, the hospital said.

No one was injured in the accident.

Martha's Vineyard Hospital president and chief executive officer Timothy Walsh said the Oak Bluffs building inspector came and the hospital brought in a structural engineer to inspect the damage following the accident. "They said the original construction was not done correctly," Mr. Walsh told the Gazette in an email. "We are now going to inspect all the porch roofs and rebuild or tear down anything with a problem. Luckily no one was hurt."

According to hospital administrator Ken Chisholm, workmen from Columbia Construction were standing on the porch roof in order to replace second-story windows when a 10 by 12-foot section of the roof separated from the side of the building and collapsed. The workers were able to hold onto the window and avoid injury, he said.

No Windemere residents or employees were nearby at the time of the incident.

"No one was at risk, nobody was out on the deck," Mr. Chisholm said.

As the roof came down it took out part of the fire sprinkler system, flooding two rooms and resulting in water damage. The area was cleaned up by 1:30 p.m., Mr. Chisholm said.

The ongoing window repair to the building is part of an extensive $3 million renovation that began in April and is due to be completed in September.

The facility was opened on the hospital campus in 1994, following years of financing and construction setbacks. According to Gazette archives, the building was designed by Facility Design and Management of Andover, and built by general contractor Congress Construction Company of Danvers, which also built the West Tisbury School addition.

In a February interview with the Gazette, Mr. Chisholm said the building has not weathered the test of time and was in need of a complete external overhaul. All windows, sidings, outside doors and decking would be replaced, he said.

The roof collapse this week "underscores the building was in dire need of renovation," Mr. Chisholm said. "This is something we will be evaluating on what needs to be done.

The repair work is being completed by Columbia Construction, which also built the new Martha's Vineyard Hospital.