This startup can turn a one-story prefab home into a 3-story house by stacking more levels like Lego blocks as your family grows — Here's what it looks like

· Housing startup Module designs prefab homes that owners can add to over time as their family grows and housing needs change.
· All of the Pittsburgh-based company's homes, which range from $220,000 to $465,000 in price, are designed to be able to change.
· But the startup is testing a removable roof system on one of three...