This data is collected through the BCMS, Building Control Management System, which is operated by the LGMA. It is collated and issued to the DECLG on a monthly basis. Each commencement notice details new residential units which will be constructed in that month.

Due to the nature of the commencement notice process, there may be slight changes to previously published data due to retrospective processing of notices.

Up until August 2015, Local Authorities or builders carrying out work on behalf of a local authority were not required to submit Commencement Notices provided that the work in being carried out in that local authority's administrative area. After 1/9/2015, Local Authority units are included in the commencement notice data.

The Dublin local authorities area includes Dun Laoghaire, Fingal, South Dublin and Dublin City. The Greater Dublin Area includes all four Dublin local authorities and Kildare, Meath and Wicklow.

Definition of the variables above: Number of commencement notices - the number of valid residential commencement notices with a commencement date in the identified month. A notice can contain details of several new residential units.

Differences to the previously collected between 2004 and early 2014: Methodological difference: The previous data was collated from 37 Building Control Areas by the DECLG. This data is drawn from a database of information held by the LGMA from data directly inputted by developers/builders online or by the local authority.

Definition difference: The 2004-early 2014 data used the date of receipt of the commencement notice i.e. a notice received in March could relate to a project commencing in April yet would be reported in the March dataset. This dataset from the BCMS uses the date of commencement of the project i.e. a notice received in February with a commencement date of March will be reported in the March dataset.

The most current data is published on these sheets. Previously published data may be subject to revision. Any change from the originally published data will be highlighted by a comment on the cell in question. These comments will be maintained for at least a year after the date of the value change.

Carlow data for Mar 2016; Adjusted downwards from 6 on basis revised data Clare data for May 2016; Adjusted upwards from 12 on basis revised data Cork city data for Feb 2015; Data adjusted in Dec 2015 from 0 to 1 on foot of revised data from BCMS due to retrospective submission Cork county data for Jun 2015; Data adjusted in Jan 2016 from 44 to 43 on foot of revised data from BCMS due to retrospective submission Donegal data for May 2015; Data adjusted in Dec 2015 from 20 to 19 on foot of revised data from BCMS due to retrospective submission Donegal data for Jun 2015; Data adjusted in Jan 2016 from 44 to 43 on foot of revised data from BCMS due to retrospective submission Fingal data for Sept 2015; Data adjusted in Dec 2015 from 10 to 11 on foot of revised data from BCMS due to retrospective submission Galway county data for Apr 2015; Data adjusted in Dec 2015 from 21 to 22 on foot of revised data from BCMS due to retrospective submission Kildare data for Jun 2016; Adjusted upwards from 28 on basis revised data Longford data for Jun 2015; Data adjusted in Jan 2016 from 2 to 3 on foot of revised data from BCMS due to retrospective submission Louth data for Mar 2016; Adjusted upwards from 12 on basis revised data Meath data for May 2016; Adjusted downwards from 43 on basis of revised data Monaghan data for Aug 2015; Data adjusted in Feb 2015 from 7 to 6 on foot of revised data from BCMS Monaghan data for Mar 2016; Adjusted downwards from 13 on basis revised data Monaghan data for Jul 2016; Revised downwards from 18 Roscommon data for Feb 2016; Adjusted upwards from 2 on basis revised data Tipperary data for Sept 2015; Data adjusted in Dec 2015 from 7 to 8 on foot of revised data from BCMS due to retrospective submission Tipperary data for Oct 2015; Data adjusted in Dec 2015 from 10 to 11 on foot of revised data from BCMS due to retrospective submission Tipperary data for Feb 2016; Adjusted upwards from 12 on basis revised data Westmeath data for Sept 2015; Data adjusted in Dec 2015 from 6 to 7 on foot of revised data from BCMS due to retrospective submission Wexford data for Feb 2016; Adjusted downwards from 7 on basis revised data Wicklow data for Sept 2015; Data adjusted in Dec 2015 from 19 to 20 on foot of revised data from BCMS due to retrospective submission