But won’t straw rot in the walls?

Any cellulose-based building material (including wood) will decay if moisture is not properly considered. Careful attention is taken to ensure straw bales do not get wet in either the construction phase or while the home is being lived in. Proper foundation and roof design are fundamental in accomplishing this, as are the choice of plasters used to seal the bales from the elements. Detailing around doors, windows, and other penetrations are carefully considered to ensure health and longevity of the home.