On Rainy Lake in Ontario, a cedar-clad cottage extends almost naturally from an outcrop of volcanic rock. Like organisms that have adapted to a harsh climate, the home’s two volumes bend with the glacier-formed ridge, their steel foundation bolted firmly to the basalt. One would hardly suspect the home was born on a factory floor roughly 400 miles away.

For Charlie Lazor, the Minneapolis architect who customized this prefab, designing from a distance is nothing new. Since 2006, his panelized FlatPak homes have shipped all across the United States, from Texas to New Jersey.

Modifying a different, modular system, Lazor was able to meet the site’s specifications with a level of precision local builders couldn’t match. “It’s a wooded, frontier kind of place,” he says. “You’re not going to find significant general contracting resources there.”

When the prefab left the factory in Stratford, Wisconsin, in early 2013, it was 95 percent complete. Braving a winter delivery, during which the truck skidded off the icy roads into a snow bank, the payload arrived unscathed and was erected in hours.

A single “kiss point” where the two modules meet defines the home’s relationship to its environment, forming a V-shaped breezeway and framing expansive views of the lake.

To let in the scenery, Lazor proposed a wall of trapezoidal windows—a challenge for the factory but a priority for the residents, retirees Dr. Mary Ellen Kennedy and Robert Dault. With a little planning, the workers were able to make the worthwhile customization. “It’s all about knowing the knobs and dials you can play with that are factory friendly,” says Lazor, “and steering clear of the ones that are troublesome.”