You might go to your local public library and look at back issues of Early American Life which often feature early PA houses. And explains how they were expanded over the years. The publisher Rizzoli has some nice books out on early houses in America and libraries buy those, too. Roderick Blackburn is an architectural historian who does some of these and although one of his is about early houses built by the Dutch in rural NY (and northern NJ, I think), he also talks in a wider sense. The library will have an architecture section and there are a number of books that explain early houses in America from early settlers' primitive cabins on upwards. They often have floor plans and sketches or even photos if available. There must have been quite a few house carpenters in Chester County who could help them/show them how to build what they needed. Liane