How much does doing the chores add to UK GDP?

Problems with measuring GDP are numerous. This report, highlighted by tutor2u explains why it might understate output
http://www.tutor2u.net/economics/blog/how-much-does-doing-the-chores-add-to-uk-gdp?utm_medium=email&utm_campaign=Economics%20daily%20digest%20Sat%2012th%20November%202016&utm_content=Economics%20daily%20digest%20Sat%2012th%20November%202016+CID_3d5718a6961c4bae44434165b8fe3300&utm_source=CampMonitor&utm_term=How%20much%20does%20doing%20the%20chores%20add%20to%20UK%20GDP%20The%20ONS%20has%20attempted%20to%20value%20the%20non-traded%20sector%20of%20economic%20activity%20-%20housework%20and%20DIY%20-%20to%20the%20UK%20economy%20Its%20value%20More%20than%201%20trillion%20per%20annum%20equivalent%20to%2056