The house is expected to go for more than its $850,000 valuation because of its prime position and its 1528sq m section.
Former World War II bomber pilot Jock McLernon owned the bach for more than 60 years.
He died three years ago on his way from his home in Auckland to the bach next door, which his brother Sam and wife Myra own. It is another modest 1920s home on a similar-sized section.
Mr McLernon's family have finally made the decision to sell.
Despite his career as a commercial pilot in New Zealand and abroad - including in Nigeria, Singapore and Sri Lanka - it was the humble home Mr McLernon returned to every year.
An aerial shot of the property shows just how little of the section the house takes up.
It is wedged beside a 410sq m Mediterranean-style home on a 2023sq m section with four double bedrooms, three bathrooms, a swimming pool and an asking price of $1.2 million, but a valuation of $1.46 million.
Having never married or had children, Mr McLernon's 10 nephews and nieces are beneficiaries of his estate.
Nephew Dave McLernon said they wished it could stay in the family.
"The nieces and nephew are now scattered around the country and overseas and the reality dictates that the property must be sold.
"Jock insisted that we celebrate the millennium at Wainui and bought the champagne for everyone. There was nowhere else in the world he would rather have been to watch the first sunrise of the new century."
Mr Robertson said the home was "almost original".
"The family think they remember Jock changing a lightbulb in 1973, that was about it."
He expected the new owners to knock the home down.
Two new builds on the beach would be worth between $2 million and $3 million.