The British Standard covering the installation of roof tiles was revised in 2015 to reflect the increasing frequency of wind events in the UK.

One significant change recommended increased numbers of tile fixings to be incorporated into both new build and replacement roofs to ensure long term durability of the roof tiles.

These changes were not incorporated into work practices by Dundee City Council’s construction services division or picked up through site inspections by the council’s clerks of works until the problem was identified late in 2019.

In January 2020, investigations identified 450 roofs that were not installed to the full requirements of the 2015 British Standard, covering 262 owners and 894 tenants.

Since January 2020, all domestic roofs renewed by the construction services division have been installed in accordance with current standards and inspections have been carried out by clerks of works to verify them.

A report set to go before councillors on the policy and resources committee notes that investigations into the situation were significantly hampered by restrictions on council services during the first Covid-19 lockdown when all non-essential activity was severely curtailed.

Councillors will be asked to approve £4.4m of corrective action for those roofs installed in the affected period to ensure consistency, long term durability and integrity as well as full compliance with the current British Standard. It is expected to take 30 months to complete the works from a start date early in 2022.

Arrangements in a number of council areas including the design and property division, construction services and housing, will also be reviewed to ensure that relevant new or changed legislative and regulatory requirements are identified and, where appropriate, addressed in a timely way.

Dundee City Council has not disclosed which homes are affected but will inform residents directly instead.

Council leader John Alexander has promised a full investigation into the error.

He said: “There will be an internal investigation through our independent audit process, a further report to the scrutiny committee chaired by the opposition and another to the policy and resources committee.

“In addition, the administration will be seeking agreement from opposition politicians for an external independent viewpoint.”

Mr Alexander added: “There were multiple points of failure including, as noted in the report, within the clerk of works service, whose sole function is to ensure standards and quality specifications are met.

“As soon as there was full clarity on the extent, nature and potential costs of this a report was brought forward to committee and councillors were briefed.”

The policy and resources committee will discuss the report on Monday.