A corner of Victorian Auckland will endure, despite a lack of official protection, now that extensive renovations are near completion.

The petite kauri cottages at 5 and 7 Nicholas St were built around 1875, according to Auckland City records, and are a vivid reminder of the past.

At the time of their construction, Auckland had just been declared a city, few streets were paved and the CBD was a largely suburban area scattered with wooden houses.

Today, the two cottages and their tiny courtyard gardens sit stranded in a sea of high-rise apartment towers.

The diminutive street is easy to miss, a one-way dog-legged lane from the top end of Hobson St through to Nelson St near Spaghetti Junction.

Half-way down are the kauri cottages, bought last year by a builder who has since made several changes.

The cottages have no protection orders and the builder, who does not want to be named, said he could easily have demolished them. Instead he worked up to seven days a week renovating them, although his changes do not reflect former historical features. He has upgraded, giving them more light and space without losing their visual appeal.

Now he plans to sell No 7, which has one bathroom and two bedrooms, for more than $500,000, but is considering keeping No 5, which is larger with two bathrooms and two bedrooms.

Quotable Value records show the two freehold properties are worth just $189,000 for rating purposes, but were last sold in April last year for $562,000.

They stand on a .0146ha plot and have a floor area of only 97 sq m.

The builder estimated he had spent at least $500,000 on renovations, which included replacing piles, wall linings, bathrooms, kitchens and making extensive repairs to the houses, which were dilapidated and dirty.

An Auckland City Council heritage spokesman said the cottages had not escaped his department's interest over the years. But the properties did not rate highly enough to warrant protection, although No 7 was of more interest than No 5.

He said historic merit assessments showed that numerous modifications to the cottages had almost obliterated the original designs; Ponsonby, Arch Hill, Newton and Grey Lynn had a number of cottages of similar design; and no significant person was associated with either cottage.

Neither cottage scored the 50 points necessary to become scheduled on the council's district plan, he said.

The builder said he aimed to make them more habitable rather than returning their original features.

A fire at 5 meant he had made the most changes there, including replacing the staircase and renewing an exterior balcony. In the next few weeks he would build a new verandah.

He installed new windows and repaired casements and some claddings. Band-sawn kauri weatherboards on 5 were sound, but he has re-clad the front in wide rough-cut pine in keeping with the historic appearance.

Heritage campaigner Allan Matson said the alterations were not sympathetic with any historical aspects of the buildings. The choice of windows at 5 was wrong - they came from another era.

He decried Auckland City's rejection of the cottages as not having historic merits.