A lawyer plans to sue actor Brad Pitt’s foundation over the degradation of homes built in an area of New Orleans that was among the hardest hit by Hurricane Katrina.

The forthcoming lawsuit against Pitt’s Make It Right foundation will be filed on behalf of some Lower Ninth Ward residents who have reported sicknesses, headaches, and infrastructural issues, lawyer Ron Austin told US broadcaster WWL-TV.

Enlisting award-winning architects, Pitt founded the venture in 2007, two years after Katrina devastated the city and essentially washed away what would become the Make It Right enclave.

Construction began in 2008, working toward replacing the lost housing with 150 avant-garde dwellings that were storm-safe, solar-powered, highly insulated, and “green.”

The homes were available at an average price of $US150,000 ($205,927) to residents who received resettlement financing, government grants and donations from the foundation itself.

But 10 years and more than $US26 million ($36 million) later, construction has halted at around 40 houses short of Pitt’s goal, and some homes are falling apart.

Residents have reported sagging porches, mildewing wood and leaky roofs.

“Essentially, Make It Right was making a lot of promises to come back and fix the homes that they initially sold these people and have failed to do so,” Austin said.

The foundation in 2014 did reportedly spend an average of $US12,000 ($16,500) each on 39 homes to replace the deteriorating TimberSIL lumber, which was billed as environmentally friendly, weatherproof and durable.

Despite that expenditure, a year later, Pitt expressed satisfaction with what had turned into a proper Crescent City neighbourhood.

“I get this swell of pride when I see this little oasis of colour and the solar panels,” Pitt told The Times-Picayune in 2015.

Make It Right did not respond to requests for comment.

The foundation did provide a written statement to station WDSU-TV when it covered residential problems in April.

“Our homeowners’ well-being and privacy are some of our top priorities and we work closely with them to address their concerns,” the statement read.

“Each situation is different and we are currently coordinating the necessary follow up with the appropriate parties to address any areas of concern.”