Construction work on the next phase of the Stanley House Hotel in Mellor, Lancashire, will start in March.
Fred Walker, co-founder of Walker Steel, acquired the property and transformed Stanley House from a dilapidated seventeenth century manor house to a hotel, opening in 2004.
The Walker family plans to add 18 new bedrooms and a luxury spa within the second phase.
The hotel's new bedrooms will be housed in a new building adjacent to the current accommodation. Each room will be 387 sq ft and individually themed.
New gardens will also be created to the rear of the spa featuring a lake and a walking path.
Fred Walker said: "I am proud to be starting the next chapter of our vision to create the best hotel in Lancashire. The hotel keeps going from strength to strength and we can appeal to customers across the country.
"Phase one of Stanley House's expansion was completed in June 2010 and saw a new glass extension added to its Mr Fred's Bar and Lounge, a refurbishment of its fine dining restaurant and a new frontage to the main building."
The next phase is expected to open by spring 2012. The project cost was not disclosed.