Before the UK leaves the EU
The Construction Products Regulation (CPR) lays down harmonised rules ('standards') for the marketing of construction products. Standards are developed by European standardisation bodies, and define the methods and the criteria for assessing the performance of the product in relation to its 'essential characteristics'. Standards become harmonised when the reference to the standard is published in the Official Journal of the European Union.
Where a harmonised standard exists for a product the CPR places obligations on manufacturers, distributors and importers of that product when it is placed on the market. The product must have a declaration of performance and have been affixed with 'CE' marking.
After the UK leaves the EU if there's no deal
The government laid a draft statutory instrument on 18 December 2018 detailing the arrangements that will apply. The statutory instrument was made in March 2019 and will come into effect as soon as the UK leaves the EU.
All existing European harmonised standards will become UK 'designated standards'. This will mean that immediately following the UK's exit from the EU, the European harmonised standards and UK designated standards will be identical. The government will publish and maintain the list of UK designated standards. This will be a UK-wide approach with the standards applying at UK level.