I braved a mist of light spring rain last week to visit the National Building Museum, where Marianne Cusato was giving a talk. The designer, best known for her work on the Katrina Cottages, has co-written a new book called The Just Right Home (Workman Publishing, $12.95). Her lecture was entitled “The American Dream Home: Past, Present, and Future”--which seemed like a pretty big topic to encompass in an hour and a half.

Ultimately, though, I was impressed at how much ground Cusato managed to cover. She engagingly explored the trajectory of popular American house types from Cape Cods to ranch houses to split levels, ending up at the much-derided McMansion. All of them “address issues, but not the heart of the issue,” she said, positing that each house type tries to make up for the previous type’s problems. For example, she noted, the excessive gabling of the McMansion represents an overcorrection to the lack of detailing on ranches and split levels.

Cusato often consults with big builders on residential design issues, so her insights into upcoming mass housing trends are valuable. “I think we’re returning to a future where the home knits into the community,” she said. “I think we’ve swung back. We can’t add any more. We have to pare down.” She hastened to add that she doesn’t mean everyone should live in a small space; just that people are starting to think more carefully about how their spaces function. And she pointed out that repetition on a streetscape is not necessarily a bad thing, showing images of San Francisco’s famous Painted Ladies.

Architectural style wasn't a big focus of Cusato's talk, but she did say she believed that clean lines within familiar forms are going to appeal to more and more people. “The form will be more traditional, but the articulation will be more modern,” she said. “The architecture will always be of its time.”