Patrick, if the millhouse is made of wood then a horizontal crosssection of the house is, in general, octangular (there are only a few whose crossections are hexagonaal). Therefore, they are said to be of the type "achtkante molens". In the case of the "achtekante" mill in Streefkerk there was for some reason no specific name, so they callen it just "De Achtkante Molen".
The stone millhouses are round.