(Reuters) -British housebuilder Barratt on Thursday expressed confidence about housing demand, but urged the government to rethink its plan to expand a tax on companies to fund the removal of flammable roof coverings from buildings. Britain last month agreed to a 5-billion-pound ($6.5 billion) levy on dozens of housebuilders to remove flammable cladding from buildings, which came into focus after the Grenfell Tower fire of 2017 that killed more than 70 people. While companies including Barratt have agreed to the levy, Barratt – Britain’s largest housebuilder – wants the tax to apply to all sta…