Simple non-chemical modifications of a typical rural house design can be an effective and relatively inexpensive method of reducing indoor mosquito vector densities and consequently decreasing malaria transmission (Lindsay et al., 2002, 2003, Kirby et al., 2008c, Atieli et al., 2009). In most parts of Africa, entry and feeding by the principal malaria vectors, An. gambiae and An. funestus takes place indoors (Githeko et al., 1994b). As a result, vector entry rates and hence malaria transmission is affected by poor quality housing which has long been associated with ill health (UNCHS, 1996). Thus, improved housing construction by simply installing a ventilated ceiling could go a long way to prevent malaria, which is killing millions of people every year.