"We have had it surveyed and found some pointing and bedding mortar missing.
"The chimney can be seen be seen to be leaning and twisting and if we did nothing, the chimney might, in time, collapse.
"So we are seeking planning permission to rebuild the chimney as part of our commitment to well-maintaining one of Ipswich’s best loved buildings.
“There is no public access to where the chimney is located and therefore no safety issues.”
It is expected that 500 bricks will require re-bedding, with the aim being to reuse as many of the existing bricks as possible.
The mansion is widely regarded as the jewel in Ipswich's crown, with its rich history stretching back more than 500 years.