Andy Burnham's promise of a council house building boom is set to blow an £8billion hole in Government spending plans, according to a new report.The new Prime Minister has vowed to oversee the 'biggest council house building programme' since the post-Second World War period.But, in new research published on Friday, the Resolution Foundation think tank found that delivering 300,000 homes for social rent by 2036 would cost £47billion.This is £8billion more than the current £39billion of funding available for the Government's 10-year Social and Affordable Homes Programme (SAHP).The SAHP, which was announced under Keir Starmer's administration, aims to deliver 300,000 social and affordable homes over the next decade.It has a target of delivering at least 60 per cent - or 180,000 - of these homes for social rent, which sees tenants pay around 50 per cent of the local market rate.But the Resolution Foundation warned of an added cost of £800million a year, over the programme's 10-year lifespan, if Mr Burnham wants all 300,000 homes to be built for social rent.This is because social rent homes offer housing associations a lower lifetime rental income than other affordable products and therefore require more grant funding upfront to be viable products, the report said.