The Globe and Mail reports in its Friday, July 7, edition that Canada's banking regulator is tightening rules for mortgages, adding new hurdles for home buyers at risk of becoming overstretched in the country's hot housing market. The Globe's James Bradshaw writes that on Thursday, the Office of the Superintendent of Financial Institutions (OSFI) released a draft guideline designed to "strengthen expectations" and shore up underwriting practices. However, the proposed rules, which include new stress tests for uninsured mortgages, would also make it harder for some would-be homeowners to qualify for certain loans. The updated rules would require lenders to stress test all uninsured mortgage loans -- those with down payments of at least 20 per cent of the purchase price -- at a higher rate, whether fixed-rate or variable and regardless of term. The borrower would need to show they could withstand a rate two percentage points higher than the rate on offer, similar to the standard the federal government mandated for insured mortgages last fall. The proposals for tougher standards come as regulators and banks express concern about surging price increases in some of Canada's largest cities.