04/21/15 - I anticipate that some inquiring minds would like to know why we are covering up the windows and door openings. The walls and roof are constructed of Structural Insulated Panels (SIPs) and have an R-value of 24 for the walls and an R-value of 48 for the roof. However, by putting another layer of insulating panel (which is called nail base) around the entire house, we can increase the R-value of the walls to 48 and the R-value of the roof to 72. While the SIPs are pre-engineered according to the design of the house, the nail base is shipped in 4’ X 8’ panels, installed on site, and then the window and door openings are cut in the nail base according to the window and door openings visible from inside the house. Remember, we will NOT have a heating or cooling system in this house, so the better the R-value on those cold winter nights and hot summer days, the Better!