A war of words has hit the streets, as builders, lawyers, and housing advocates try to identify the root causes of the housing affordability crisis. One take on the problem points to defect lawsuits. A recent report by The Philadelphia Inquirer suggests that builders in the Mid-Atlantic region who put the most housing on the ground have been hard-hit by such lawsuits, which in turn jacks up new-home costs.

Attorneys argue that builders themselves are to blame. They suggest that builders too often use low-value products, don't build to code, or don't make needed repairs.

But, as former NAHB president Gary Garczynski, of Woodbridge, Va., notes, outdated zoning and NIMBYism may be the greatest threats to affordability nationally. After all, if housing can't be built, the unmet demand will always drive prices higher.

There are other forces quietly at work as well, undermining affordability from the bottom up. For example, the federal government used to provide a safety net in the form of affordable HUD-subsidized and insured housing. According to the National Housing Trust (NHT), however, the contracts for subsidies on much of that existing stock are now expiring. And the owners are converting it into higher-cost, market-rate housing. The NHT reports that "private owners have already 'taken to market' over 150,000 HUD-assisted or insured apartments, and an additional 2,000 such apartments are losing affordability monthly. The average rent hike associated with conversion from 'regulated affordable' to market rate is 45 percent."