Using novel time-use data from Germany before and after reunification, we document two facts: First, spouses who both work full-time exhibit similar housework patterns whether they do so voluntarily or due to a full-time mandate, as in the GDR. Second, men's amount of housework is independent of their spouse's labour supply. We theoretically explain this pattern by the presence of two household goods and socially learned gender-specific comparative advantage in their home production. We label this gender specialisation as separate housework spheres. Empirical evidence strongly confirms separate housework spheres in the GDR, West Germany, subsequent years post-reunification, and in international time-use data across 17 countries since the 1970s. We consider several implications, such as those for child penalties, where separate housework spheres provide a novel explanation for why it is the mothers whose labour market outcomes strongly deteriorate upon the arrival of children.