Heritage experts are at loggerheads over plans for a towering hotel at the Britomart heritage precinct.

Leading heritage architect Jeremy Salmond, hired by Britomart developer Cooper and Company, is a lone voice in saying a tall building would not devalue the heritage values of the precinct.

Up against him are the Historic Places Trust, heritage campaigner Allan Matson and Auckland City Council's senior heritage architect, Ian Grant, arguing in favour of retaining a "quality low rise heritage-based precinct".

Today, planning commissioners begin hearing a private plan change by Cooper and Company for the Seafearers Building site on Quay St.

The developer plans a stepped building made up of two heights - 55.2m and 35.4m - to echo the pattern of different heights along Quay St. The allowable building height for the site is 24m.

The stepped plans for the Seafearers' site are the second attempt by the developer to breach the allowable height limit in a block of heritage buildings that includes the Union Fish, Police Wharf and Northern Steamship buildings.

The developer has backed off a previous plan to build a luxury 175-room hotel of up to 101m for the 2011 Rugby World Cup.

Cooper and Company has received a lot of praise for restoration work on 18 heritage buildings in the Britomart precinct, but the overwhelming majority of submitters to the plan change oppose a tall hotel on the Seafearers site.

The developer received a big setback when the Auckland City Council came out against the plan change and recommended it be declined.

Mr Salmond, who specialises in conservation of heritage buildings and writes extensively on heritage conservation, believes there is no contradiction in introducing new buildings into heritage settings where they replace unsympathetic existing buildings - ie the Seafearers Building.

In a report for Cooper and Company, he acknowledges the historical scale of the Britomart precinct is generally five storeys or less, but notes there are taller modern buildings further west along Quay St and the new "East" building inside the precinct is 12 storeys.

In his view, the effects on heritage values of a tall building complying with the guidelines will be slight.