While settlers in New England would eventually roof their houses with shingles (assuming they could find a large enough cedar tree), that would have taken too much work to start out with. Each shingle would also need (at least) two nails, and all nails had to come from England and were thus a precious commodity. The easiest roofing material was thatch: large bundles of cattails or marsh reeds. Thatch or reed roofs needed no nails at all, were impervious to rain, and when they did leak, all one had to do was to put another bundle of reeds on top. Carefully done, a thatch or reed roof could last more than fifty years.
The roof was placed on top of four posts at the four corners, and the early houses had only a single room -- everyone (parents, children, servants) ate and slept in the one room, and at night sheets or curtains might be put up for privacy. In the next generation, as houses became larger for fewer people, a second floor or a loft would be included. It is still astonishing to see the size of some of the first generation houses: the footprint of the original house of John and Priscilla Alden at the Alden First Site in Duxbury seems (by modern standards) to be tiny (10 x 38 feet) -- one can almost touch both opposite walls at the same time when standing in the centre of the building. And there were, at one time, not only John and Priscilla, but also their ten children.