Others have already suggested this idea but the Wall Street Journal reports on another call for turning McMansions into affordable housing:

McMansions, a type of home became popular with affluent boomers during better times, have fallen out of favor as more consumers seek smaller, more affordable homes that cost less to operate. They also want to trim the gas tab by living closer to their jobs and public transportation – the opposite of McMansion developments deep in suburbia filled with gas-guzzling SUVs. (There’s no precise definition of a McMansion, but it’s often a case of you know it when you see it.)

Such changes in taste — and, of course, the foreclosure crisis — has left America saddled with about 30 million more homes on large lots than the market needs, The Atlantic Cities writes. But rather than let them languish on the market indefinitely, Mr. Nelson suggests converting these excess homes into affordable housing or housing for multi-generational or multi-family households. (Developments called Mr. Nelson for comment, but he was not available.)

Such homes, he points out, can have more bathrooms than bedrooms, allowing for residential space that could be divided into private units, with a common kitchen and living room. Some already have or could be outfitted with second or third kitchens. Plus, there’s plenty of room for several cars and, usually, enough of a backyard for a swing set or two.

“When you add up the spaces and how they’re distributed, the typical McMansion can be occupied by three-to-five households with their own splendid privacy, their own large space,” Mr. Nelson is quoted as saying.

Just because there may be these larger housing units available does not mean that it would be easy to make them into affordable units and/or rentals. Here are some obstacles:

1. Whoever owns these houses would have to agree to this. Would the owners want this or is this an idea from critics who don’t like these homes that want this to happen? If the homes are in foreclosure, do the banks want to jettison them quickly and do the new buyers want to convert them into more units?

2. One can’t go into many neighborhoods where McMansions are located and simply subdivide the houses into five or six units. This would require zoning changes or special exemptions from a community. If the neighbors found out about this, I imagine many would not be happy. How many would want several houses in a large neighborhood to start being effectively apartments/condos? There would be questions about traffic, safety, and perhaps under the surface, who exactly would be moving into these affordable housing units.

3. The locations of many of these homes could still lead to affordability issues. If the McMansions are in exurbs, it would require a lot of driving to get to jobs, schools, and other places. The houses may be more affordable but the other costs of sprawl would still show up.

These are not insurmountable issues but it is not necessarily an easy or quick path from McMansion to source of affordable housing.