Hilchos Pesach – 11 / searching for chametz

1. All the rooms of one’s house must be cleaned before conducting bedikas chametz; one may not rely on the search alone. Conversely, one may not rely only on the cleaning. Therefore, even if a person cleaned his house thoroughly and verified that there was no chametzleft, and was careful to not bring in any newchametz, he must nevertheless conduct a proper search forchametzon the night of the fourteenth (Shulchan Aruch and Mishnah Berurah 433).

2. Some have a custom to use a feather during the search in order to use it to extract chametz from the holes and crevices (ibid.).