As regulators discuss significant changes to the mortgage market, a recent report says making high down payment requirements part of the deal will lock out many people looking to buy Houston homes.The Center for Responsible Lending says that requiring a high down payment won't prevent many foreclosures, but it will keep many creditworthy buyers from getting a mortgage. Examining loans made from 2002 to 2008, eliminating people who didn't make a 10 percent down payment would cut more than 10 percent of the market in some years.The report added that in order to get a 20 percent down payment, the average American family would need to save up for 14 years, compared to the current six.The government's qualified residential mortgage – or QRM – rules are expected to be released this month. Loans that don't meet those standards will likely come with higher fees or interest rates. Many reports have said they will encourage a 20 percent down payment.The comments echo those made by some lawmakers who helped write the legislation. Georgia Senator Johnny Isakson says that a 20 percent down payment would shut many buyers out of the market, and it wasn't what officials envisioned when they created the rule.